Honda-SOHC
SOHC.co.uk Forums => CB750 => Topic started by: MrDavo on July 13, 2016, 04:26:21 PM
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The good news is Candy runs well, looks wonderful, getting compliments from everyone who sees her, and has won best Japanese Classic at 2 of the 3 bike shows she has been entered in. However, it looks like she's about to be pulled apart. She has been restored at some point while in South Africa, but I've no idea what engine work, if any, was done until I get inside.
Fault 1:
While Candy runs ever so sweetly, with very little mechanical clatter, when she gets proper hot, such as after a run 2 up with the camping gear on board, I am sorry to say there is a definite low 'knock' which I can feel as well as hear. Pulling the clutch in makes no difference, so I don't think its the clutch basket rattle that some have suggested. Also, the oil light comes on at low revs, to be expected I know, the manual says it is normal, however the hotter it gets the higher the revs needed to make it go out again.
Fault 2:
This has only happened twice to me, but she is 45 years old, so who knows how many times it has ever happened.
200 yards from my house, (the same piece of road both times) the oil light comes on solid, not flickering, whatever the revs, and a clatter - as fast as I can pull over it goes as quickly as it happened and doesn't reoccur.
I suspect that fault 1 (the knock) was caused by fault 2 (oil starvation), and was already there when I bought her - coming back from the MOT (my first ride) I had issues with the oil light coming on at idle and being reluctant to go out again as I revved.
I have replaced the oil pump 'O' rings, oil pressure light sender, and tried heavier (20/50) oil. An experienced race mechanic I spoke to at Classic Le Mans last weekend suggested I could try over filling, with thinner oil, he suspects the thick cold oil just isn't flowing fast enough to keep up until it gets warm, leaving the oil pump trying to pump fresh air, he agrees it may have done for the main bearing shells over time. He also told me about classic Bugatti race mechanics having to warm rear axles with blowlamps, the lubricant they use solidifies to something like candle wax at normal temperatures!
I'm going to try pulling the oil supply line at the motor, to see what the flow is like when the engine is cold - maybe it's partly the viscosity, but perhaps there's a partial blockage or collapsed rubber inner in the oil feed line (every other bit of rubber on the bike was shot due to a combination of age and long term storage in a hot climate).
Even if I can stop it happening again, the bottom end won't fix itself, and I am reading up about using plastiguage to measure running clearances. I wanted to take the motor out anyway to polish the cam cover. D'oh! ::)
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Have you tested the oil pressure ? And is oil spitting out the tappet caps, when removed ?
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No I haven't tested the pressure yet, but the local garage that does the wife's car has said I can use his gauge, he has a range of fittings so I'm hoping he has the one to fit on the end of the gallery.
There is oil at the tappets (and a slight top end leak).
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Something really strange there.
You're already effectively running 20 viscosity oil anyway when the oil temp is down as the base oil is that rating and only behaves like a 50 when heated via the performance of its viscosity additives when reaching 100 deg c as I understand it.
Honda's manual for that engine states that SAE 20 oil is ok from zero deg c so you should not runs into problems from it at current temps.
I also ran these 750's on 20/50 oil including winter use of below zero and even got a K6 stuck in the snow with never any problem with oil pressure.
The pump is a dry sump so should never be able to suck air, as long as the levels are ok.
You may be onto something in verifying the oil hoses are intact internally as that could cause starvation. Have you checked the pressure relief valve on the pump?
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There was a batch of oil feed lines fitted from the factory that had an internal "Kink" and restricted flow, as far as I know they should all have been changed under warrantee along with the crank and shells.
If you "clonk" is a bad bearing you will need a different crank and shells as these cranks can not be re ground
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Oil light on steady with associated knock from the engine, that's a knackered bottom end for me. Take it off the road now before you do irreparable damage to the crank. Sorry mate.
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If its knocking its already irrepairable mates
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I suspect you're right, the crank is probably toast, but I'm not looking for a new one until I see for myself. I'm not going to run it until then, my 1200 Harley Sportster did a crankpin, then the metalflake oil did for all 4 cams as they seized in their bearings and span them in the cases. It took a year to fix that mess, if I'd stopped as soon as I heard it going 'potato, clank, potato, clank' I could've avoided a lot of the secondary carnage, but I went through a 'denial' phase first, until it became too loud to ignore.
The odd thing is that she runs very smooth and quiet until it gets hot and the oil thins, you'd think shot mains would knock all the time.
I do need to get to the bottom of 'why' first - if, say, the oil feed line is collapsing internally under the braiding, it could repeat the process even after I fix it, I will be having a close look when I get it apart, I may even replace it anyway as a precaution. Those two little episodes where the oil light came on as it suddenly lost pressure, then got it back, both with cold oil, just up the road from my house, are very significant I think, as well as very unusual. I shall also be having a very close look at the oil I drain out. I have an impressive collection of glitter that I washed (using white spirit) out of the Harley oil tank.
Not great, but not the end of the world either, I've fixed much worse.
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A knock is usually a big end caused by the change of direction of the Conrod. Mains are usually a low rumble noise. As Brian says you can't regrind these cranks but if the damage is tiny they can be micro polished. Good luck with it hope it goes well.
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A knock is usually a big end caused by the change of direction of the Conrod. Mains are usually a low rumble noise. As Brian says you can't regrind these cranks but if the damage is tiny they can be micro polished. Good luck with it hope it goes well.
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Can be reground to STD size after metal spraying. You can't get oversize shells.
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Have you had a crank metal sprayed Trigger? How did it turn out, I have one that could use that technique.
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Cranks and cam shafts for the past 26 years ;)
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Cranks and cam shafts for the past 26 years ;)
Who do you get to do them Trig?
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Roy, S.E.P. in Kegworth reclaim cranks by submerged argon arc welding then regrinding back to the original sizes. Used them myself, very good work, and they can usually supply shells as well.
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Cranks and cam shafts for the past 26 years ;)
Who do you get to do them Trig?
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T&L Engineering in Bedford.
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Thanks guys that's two contacts to keep.
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A long shot folks.........and I'm sorry that it's not about my venerable old Honda.
I have two Triumph 1970 650 Twin Crankshafts which I need to refurbish. Each has a cast Flywheel which is heated and shrunk on to the Crankshaft and held in place with 3 bolts. I think each Flywheel is cracked which makes them junk..........unless I can obtain the unobtanium - and find new Flywheels (hahahaha) - or I can find a Foundry who can cast some new Flywheels (using the old Flywheels as patterns) and a machine Shop who can make them fit.
Do any of you fine upstanding people know of a Company who might be able to assist me? I live in Lytham St Annes but TBH distance is no object (as long as its in the UK).
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Always check the rods because once they start knocking, it can oval the con rods.
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There is a company in Kent, Dial Patterns that could make the pattern for a foundry to fill. Don't mention my name as I still owe them funds ;D
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Thanks for the contacts, I'm not counting any chickens until I get her apart, but Trigger's firm in Bedford could be the way to go, I've had a look at their website, and I'm off to the Silverstone Classic in 2 weeks, so I could maybe drop the crank off on the way.
I still don't see why a big end would be intermittent, surely they clank all the time when they are shot? Maybe that thick 20/50 oil works better than I give it credit for.
I still have to find out why, and what the mystery sudden pressure loss is all about, or I'll be doing it all over again next year. Tomorrow the car will be banished outside so I can use the garage space and I'll start dismantling. The oil feed line feels a little squashed around the kickstart boss and footrest, I'm going to drain the oil by disconnecting the line at the oil pump end, and see what happens when I drain the tank while the oil is cold.
Edit:
Tell me more about the oil pressure relief valve, I see it mentioned in the similar thread by Yozzer74 - I now realise the one I checked and cleaned was in fact the leak stopper valve, also I checked the the sprung valve in the oil filter. Looking at this page:
http://cb750k2.honda4.nl/lubrication-system/lubrication-system.html
It seems there is another third valve which I haven't checked, and sticking can result in poor oil pressure. Worth checking first, or too late now?
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You've a very unusual set of circumstances that look to be a possible cause.
If you think about "traditional" low oil pressure, that would be the engine bearings worn enough to allow the oil feed to leak out faster than the pump can put it in to fill the gaps.
What you appear to have is "within reason" a relatively unworn bearing set (unless further running totals it)but a restricted supply so the leak out is normal but refilling the bearings is not happening fast enough. The con rod upper shell is effectively prevented from getting much oil into the area during the power stroke and relies on the non compressive part of the stroke to replenish the oil that separates the shell from the crank. If you restrict the supply, that replenishment won't complete in the time available so the next power stroke gives you a clonking as the shell hits the crank pin.
The mains have nothing like the percussive load inflicted on them so as previously posted they'll generally not give the same sort of noise.
There is no real restriction going to the pump in a dry sump system but a collapsing feed hose would definitely make one that the pump could not overcome.
That's very informative from Bryan (hat off to him for remembering that) as it could be key to your problem. There's not many forum with that in depth level of knowledge available.
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I remember it because my one time boss, Neal Frazer, who owns Frazers of Gloucester bought a K? from Skellerns of Worcester with all the goodies (Tank. bars, sidepanels,etc) removed and had the frame and swingarm nickel plated then built a "New" Dunstal. Two weeks later it started knocking and he had to take just the engine to Skellerns who took over a month to fit new crank, rods and shells also supplying the new oil hose. It may even be in the bulletin list--not sure
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I have the hoses off, although I cannot be certain we've found the problem until I fit new hoses and refill with 10/40, the supply hose has a kink (not terrible but still a kink) where it bends 90 degrees, a simple but messy experiment pouring oil into the tank and watching it come out of the motor end saw oil coming out faster when the hose was straightened.
(http://i34.photobucket.com/albums/d144/roycropper/IMG_1221.jpg)
New OEM hoses are NLA (thanks again Honda), but an eBay search found a man in Germany who does a service exchange service fitting new stainless braided hoses to used fittings, not cheap and priced in Dollars, but the best I'll get.
Even if it doesn't solve my problem and I have to pull the motor I reckon that's what caused it, it will look better and I will have eliminated the poor feed. Interestingly my Haynes manual (I have little faith in these but at least I can take it in the garage unlike my virtual Honda manual) mentions bad oil hoses sometimes causing low pressure, so they must have read the bulletin too. A Google search tells me Honda bulletin 750#35 dated 11/72 was called 'Revised Oil Tank Feed Hose', but no trace of it online anymore, Ash will know, but it seems that the US site bottled it and pulled their online service bulletins - why the hell would Honda sue their loyal customers over copyright on 40 year old bulletins?
While I'm at it, Ive pulled the oil pump again, all looks well and I checked the pressure release valve too. A couple (literally) of metallic flecks on the strainer, also tiny bits of my new clutch friction plates but nothing scary.
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That kink looks pretty severe to me.
If that was a rad hose you would bin it.
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Well the good news is that the oil hoses arrived from Germany, and very nice they look too:
(http://i34.photobucket.com/albums/d144/roycropper/IMG_1257.jpg)
They were a struggle to fit, as they are not a millimeter longer than they have to be, and very stiff - it took a few attempts with each hose until I found the correct sequence of assembly so they would fit. I thought of spraying the stainless braiding black, but decided against it as they'd just look scruffy when the paint starred to flake off.
Anyway, that's the least of my worries, after I fitted a new filter and some new 10/40, I went for a test ride. From this picture, taken later in the day, you can guess how that went:
(http://i34.photobucket.com/albums/d144/roycropper/IMG_1261_1.jpg)
Fine until it got hot, then the knock was back. I limped home slowly, and dropped the oil. This time, because it was new and clean, I could see the dreaded 'glitter' in it, no question. Although I've fixed the cause, the crank is already goosed, and isn't going to fix itself. B*gger!
I've wondered about a second hand crank, DK have one, and I know a guy in Stockport with a load of used CB750 stuff. However what you don't know is why the bikes they came from were stripped / scrapped in the first place. Unless I go with a micrometer, measure every journal and compare it to the spec sheets, I could easily buy a whole load of more trouble. What do you think?
The motor is nearly ready to come out, I'm stupid busy this week though, so it may not get pulled and stripped straight away. :( I am keen to see how bad it is though.
The contact in Kegworth seems promising, if only because its a lot nearer than Bedford, however there's always the post. How feasible is it to post a CB750 crank though? What would I have to pack it in? Probably not a Jiffy bag.
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Hoses look good but a shame it's too far gone to get it going, I was hoping for you that you may have got something more positive out of it.
To send the crank, could you wrap it in clingfilm then stand it on end in a strong box on a polystyrene block and use expanding builders foam to in effect create a bespoke cradle to protect it?
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I would wait until you strip the engine, before thinking about your course of action, your crank may be okay.
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Cranks rarely go so a used one should be OK but get one with rods as if its knocking the rod concerned will be toast guaranteed
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If that's the case then a second hand crank will be the answer - if I have to change a rod then I have to find one with the same weight (there are 3 grades) to match the others or the balance will be out. As Roy says I won't know for sure until I get in there, but there's not much doubt in my mind that a big end is fubar, after combining the knock with the sight of metalflake oil.
Sadly time and the need to reorganise in the garage to do the job means it may be a while, but I'll update you when I know more. I wanted to take the motor out to polish the cam cover anyway. :(
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I might have a crank to sell. I do have a collection of rods too but they are a mixed bunch from other cranks. I had both of my cranks miked last year by a top engineering guy who sadly passed away last year and they were both fine. Just need to check that they both are the types that take M8 down to M6 advance bolts as Trigger told me me that not all 750 cranks are the same up to the Auto ( I was previously told by a top sandcast restorer that they were interchangeable up to the auto), which has a HyVo chain. I want 25 quid for it if you are interested as long as both have M8 advance bolt tappings. Pretty sure the spare crank came from an F1 and I do still have the engine number somewhere.
I am in East Yorks BTW
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Thanks Ash, though do check the thread for the ignition stud. While I realise they should not be taken as an authority on compatability, one crank DK had was listed for CB750K 1970-77, another they have is listed as only for a K6. Confusingly, according to John Wyatt's book, F1 comes in at 1976, so does K6, so there could be a change to something around then, it certainly needs checking out.
If it will fit, I'd certainly take you up on your offer, subject to what carnage I uncover, if you have a few rods I'm sure we could pick one out with the same / similar weight code letter, I can print out the Honda service bulletin (which you may have put online) saying which rod goes with what.
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I had to nip home at lunch as the missus is away and I thought I had left the steam iron switched on :-[ :-[, so I checked my cranks. It's defo got the 8mm thread same as the other one ... so over to Trigger ;D, the F1 engine was one with the more domed 392 pistons.... Thinking about it, I may have a couple or more of it's original rods. Bryan is correct, when the big ends go the shells move in the rods and scuff the surface... it happened on my K0 engine. Are you in Yorks or Lancs?
You don't want the con-rod that I caught the wife using as a litle hammer to hang a picture hook ::) ::)
[attachimg=1]
[attachimg=2]
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I did show you that the cranks are different Ash, so how they are the same part number is only something that MR Honda can explain ;D
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The F2 crank appears to have the same part number as well but I'm sure they are unique to the F2?
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I did show you that the cranks are different Ash, so how they are the same part number is only something that MR Honda can explain ;D
But mine both have the M8 thread on points side ..so are they OK for the early bikes?
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[attachimg=1]
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I had the braded hoses made when doing the rebuild.
Click image Link to enlarge
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Very neat Greebo, they look like the ones I have now. A mechanic I do work for tells me I could have had mine made up by a local firm using my ends.
My original kinked pipe looks more like the 'molded' one in Ash's service bulletin, the bend they put in it is where it kinked. Unfortunately the feed pipe is the one that's hidden behind the return hose and oil tank - it's something everyone should check at least once.
Once bitten twice shy, as Ian Hunter said.
I've been in touch with Ash, it looks like his F2 crank will fit OK and we can look in his parts box for a matching rod (assuming only one is fubar). Can I split the cases to get the crank out without disturbing the clutch, gears and gearbox sprocket, or does it all have to come out so I can get the crank free of the primary chains? I'm guessing so.
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It's easiest to have the cases upside down, lift the gearbox mainshaft with clutch up and withdraw it from the primary chains, the you can put the mainshaft back in if you want to. The crank is then easy to lift it out, I wouldn't try to thread the crank through the chains while they are still round the gearbox shaft and don't think it'll go anyway.
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Thanks, that just what I wanted to hear, it means I don't have to dismantle the gearbox, clutch, selectors, sprocket etc unless I need to.
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Thanks, that just what I wanted to hear, it means I don't have to dismantle the gearbox, clutch, selectors, sprocket etc unless I need to.
That could prove a false economy. Personally I would totally strip the cases, and check all the oilways are flushed through and blown through with compressed air, seeing as you found metallic filings and nasties in the oil you drained. Think hard about it, do you want the possibility of having to do it all again and more for the sake of not completely stripping it now?
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When you get that far, you may as well do the chains and look at the chain tensioners, rebuild the oil pump and so on.
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They are money pits to rebuild properly agreed. It's an F1 crank I have BTW not F2. One way of getting it to you safely would be to ask my mate as he goes on Sunday, at least twice a month, buying his mobile phone parts from a wholesaler in Manchester. You are always welcome here though. As I said, I also have a really nice early gearbox inc primary drive. Also a large box of gears but of unknown condition.
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I'll see where I'm at when I've got it in bits, I take the point that it all wants to come out for a good clean. From experience I'm very aware of 'mission creep', I don't want to get carried away if I can help it.
From the external condition, and the lack of mechanical noise (other than the death rattle when hot!), I think the motor had been rebuilt when the bike was restored, so I'm hoping that most of it will be good. I checked the oil pump out at the weekend, it all looked OK. I could do with fixing the wet sumping though, Trigger you said on the other oil pressure thread that you do the stopper kit yes?
Another 'while I'm in there' job will be to fit the heavy steel 'case protector' around the drive sporcket, which is absent - anyone got one?
@ Ash, your mate might be a good way to go, but I need to see what rod(s) I'll need first, in the hope that you have one (or more) the right grade to make a matching set. I'll fit new shells and mains after miking all the journals up, that doesn't look to be a cheap undertaking.
Any recommendations on gasket sets? some don't have all the O rings, yamiya do one at great cost, but I'm sure good quality.
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I'll see where I'm at when I've got it in bits, I take the point that it all wants to come out for a good clean. From experience I'm very aware of 'mission creep', I don't want to get carried away if I can help it.
From the external condition, and the lack of mechanical noise (other than the death rattle when hot!), I think the motor had been rebuilt when the bike was restored, so I'm hoping that most of it will be good. I checked the oil pump out at the weekend, it all looked OK. I could do with fixing the wet sumping though, Trigger you said on the other oil pressure thread that you do the stopper kit yes?
Another 'while I'm in there' job will be to fit the heavy steel 'case protector' around the drive sporcket, which is absent - anyone got one?
@ Ash, your mate might be a good way to go, but I need to see what rod(s) I'll need first, in the hope that you have one (or more) the right grade to make a matching set. I'll fit new shells and mains after miking all the journals up, that doesn't look to be a cheap undertaking.
Any recommendations on gasket sets? some don't have all the O rings, yamiya do one at great cost, but I'm sure good quality.
yes, I do the stopper kit and have stock. PM me with your requirements
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Trigger, you have a pm.
Photo taken this morning with my beautiful assistants, Big Leigh on the left can single handedly lift an H-D 1200 motor into a car boot, so handy to have around. We each wrote a guess for the 'motor in' date on the garage wall. We expected a lot off faff after watching those clowns on the telly doing it, but it all came out suprisingly quickly and easily. 'Prior preparation prevents piss poor performance' as they told me when I was firing steam locos for a hobby.
We didn't resort to lifing the bike off the engine, because we couldn't be bothered taking off (and putting back on again) the wheels, and possibly the indicators, but did it the old fashioned way.
Eddie is an engineer, and will be providing calibrated micrometers, borrowed from work, and an ultrasonic bath for the carbs. It also did a lovely job on our coffeee machine's filter 8) .
(http://i34.photobucket.com/albums/d144/roycropper/IMG_1407.jpg)
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Well I got the head off. Number 3 exhaust pipe has always been a little bit straw coloured, but I thought I'd fixed any air leak when I tightened up the inlet rubbers. Obviously not. I need to look at that carb - partly blocked main jet or fuel feed passage? Any other suggestions? The tappet gaps were right, btw.
(http://i34.photobucket.com/albums/d144/roycropper/IMG_1411.jpg)
The head gasket delaminated as it came off, while all looked clean and new in there, I think it was all put together a long time ago. The bores and pistons all look good so far, no visible wear.
(http://i34.photobucket.com/albums/d144/roycropper/IMG_1412.jpg)
The big PITA at this stage is that the barrel is reluctant to come unstuck. There doesn't look to be any jointing compound, but I'm nervous about using force. Tapping with a rubber hammer hasn't worked, I gave up and came in after a while. Any good suggestions?
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Futtocks! After going in the garage last night to strip my engine I have
!) Broken my workmate - off to B&Q soon to buy a real wood plank top, not the cr*p fibreboard it came with. It did say '100Kg weight limit', not sure what a CB750 motor weighs.
2) Wrestled with it on the floor and decided to invest in one of Trigger's engine stands.
3) Failed to get the barrels off. I may now wait until I can hold the motor securely, but I've tried the putting rope in the bore and the head back on (held with the 4 screws) and trying to turn it over trick. It didn't budge. I'm wondering whether to remove all the studs now. I've tried tapping with rubber mallet and wooden blocks, I'm scared of using extreme force though.
I also tried to buy an NP gasket set on eBay, but later the seller rang to say that the borrowers had been in the packet, so the order had to be cancelled. :(
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You can still strip the bottom end and get to the crank etc for inspection with barrels still on. I cant remember but there may be small recesses in the castings to get a pry tool in. Sounds like butchery I know but sometimes you will need to do it. Trigger/Bryan/Oddjob will know they are the pros's on here.
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I wouldn't take any of the barrel studs out unless you are replacing them, or need to for any other reason. You'll give yourself a big headache if you get into that.
You can try to gently, using a rubber block, or something similar, to tap the top of the barrels first forward and then backward to see if they will release from the gasket and dowels. It's not much but just enough to break the adhesion at the base. Right at the top level with the head gasket surface so you are in effect using the barrels themselves as a lever to rock them loose while not putting any up or down blows onto the fins as they will snap.
The studs should not ordinarily be holding anything as they are all waisted down their whole length and so generally have clearance for the barells.
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You could always get someone with strong arms to lift the engine by the barrels about a inch off the ground and then tap the crank case with a plastic/rubber mallet.
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You could always get someone with strong arms to lift the engine by the barrels about a inch off the ground and then tap the crank case with a plastic/rubber mallet.
Sounds like a job for Big Leigh, from the photo at the top. Just come in from more ineffectual tapping and prying, no joy, that bugger is stuck - I was even considering using man's red fire.
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My engine stand arrived, thankyou Graham, the motor is in it now, all very smart and stable.
The barrels are well and truly stuck, the problem is time, rather than corrosion, but how the heck do people strip the projects are are rusted solid - my pistons are free but it still won't shift one iota!
(http://i34.photobucket.com/albums/d144/roycropper/IMG_1413.jpg)
No stand here, but this is me attempting to use gravity, with a ratchet strap hooked in the cam chain tunnel and to the garage roof beam. Its only a concrete garage< I got the engine swinging about, beat it around with a rubber mallet - later attempts included studs out and heat on the dowels in the front corners, also an attempt with a pallet knife. I gave up before I pulled the garage down from within! :o
I'm minded to give up before I do real damage and seek professional help, though I'm not sure who from yet. My local garage says I can use their hoist, but the guy worries that I'd break the cases or barrels before it pulls apart mechanically.
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Hi Oddjob, in desperation I took the studs out last night, I didn't mark them as I used 2 head bolts tight against each other on each stud to wind them out. I had put penetrating oil down first, but I saw no corrosion on the studs, There were a couple of 'pings' that made me think things were tight down there, but I'm no better off. I pushed the loose studs through a card so I can keep track of which is which.
The head and rocker gaskets totally delaminated, leaving half on each surface. I think the base gasket wants to do the same, but can't.
Stripping with the barrels on is a last resort, but I wouldn't fancy reassembling it that way. I've doe a bit of prying here and there but bottled it before I do significant damage.
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Before I try that, a friend who's in the bike trade suggests a chemical attack first - either thinners or Loctite 7200 Gasket Remover. As the head and upper barrel is such a mess I think I will get some.
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I eventually took it apart anyway, barrels well and truly stuck on, pistons and rods still in the bores. I stupidly popped a ring out, I had to weasel it back in with my fingernails, which took ages.
Entry, risking the garage roof again with a ratchet strap. Note Trigger's stand coming in handy. Also the Aldi work bench's compressed cardboard top has been replaced with some proper wood after an, er, accident.
(http://i34.photobucket.com/albums/d144/roycropper/IMG_1414.jpg)
First glimpse of a main bearing:
(http://i34.photobucket.com/albums/d144/roycropper/IMG_1416.jpg)
Strangely although all the mains are toast, shells and crank, the big ends are fine, so I don't need any rods, Ash, I may need a rotor and ring gear yet, though, that big bolt isn't for shifting.
(http://i34.photobucket.com/albums/d144/roycropper/IMG_1417.jpg)
Oh, the horror!
(http://i34.photobucket.com/albums/d144/roycropper/IMG_1419.jpg)
I should cable tie up the rods, so they don't flop around and ding the pistons.
(http://i34.photobucket.com/albums/d144/roycropper/IMG_1420.jpg)
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Those shells are toast, you should never be able to see the copper, and with that i suspect the crank is as well
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Plus 1 with Bryan, that crank is toast. That's what happens when the previous owner ignores the essential oil change regime. Crank can be repaired but probably easier and cheaper to find a replacement.
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There is a big problem I see in the photos, apart from the crank and shells, why is it so clean inside ? Not a oil stain in sight.
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There is a big problem I see in the photos, apart from the crank and shells, why is it so clean inside ? Not a oil stain in sight.
Your right that is incredibly clean. Pump failure do you think or maybe no restrictor jets fitted?
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The crank is definitely toast, all the main journals are scored. Ash has sourced me another, see earlier in the thread. I'm dropping the goosed one off with an engineer later to see if he can get the rotor bolt out after I get the points stud off.
The whole bike is that clean inside and out, with fresh pistons and bores as far as I can tell, it was apparently restored fully years ago and never used again. The failure was due to a kinked oil feed pipe, starving it of oil, again see earlier.
There is oil in the motor, I think its never managed to stay in long enough to start to get dirty. That said, I've found that one of the 3 oil pump dowels (with the o ring round it) is slightly distorted out of round, and not a great fit in its slot in the pump, I need to change it - CMS seem to have them. I'm guessing that that alone could be a cause of the low oil pressure, that combined with the kinked hose sealed the engine's fate.
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The low pressure is simply the excess clearance on the mains, the real problem is what caused that
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I think the mains were initially borked by the low oil pressure, caused by the kinked oil feed, it's a bit chicken and egg. Twice after start up the engine has suddenly found itself with no oil pressure at all for a few seconds since I got it as the cold oil hasn't fed the pump fast enough and the pump has found itself pumping fresh air. As the oil light stayed on at higher than expected revs on the first trip to the MOT, I assume whatever event killed the crank had already taken place.
Obviously once you have low oil pressure, it just makes itself worse. This is what I assume caused it, but I will check for a blockage in the oilways. There is an oil metering jet in the head, are there others? It is possible there is still something wrong, but I don't see what, the oil pump has drive and returns oil to the tank.
Another theory suggested is that the motor was completely rebuilt (this is why its all so clean, it was vapour blasted like new inside as well as out, though not threads or gasket faces) then left for a long time and was subsequently started up bone dry.
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The vapour blasting could explain why everything is toast. If any of the glass bead was left in any of the oil ways, it would of acted like grinding paste. Love to see what the inside of the oil pump looks like.
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Takes quite a bit to remove all the white metal down to the copper, not just a couple of seconds
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Takes quite a bit to remove all the white metal down to the copper, not just a couple of seconds
He did say that he rode it to the MOT station, and most probably back.
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A busy day Sunday. I polished the cam cover at last, stripped the carbs for an ultrasonic bath and the choke linkage for a replate.
I also removed and stripped the oil pump. The rotors and their fit together are like new, with slight scuffing, but the endplates are badly marked up. Some scratches in the body but not much. Trigger, are these toast or useable?
(http://i34.photobucket.com/albums/d144/roycropper/IMG_1429.jpg)
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Have not seen any used pump covers without slight marks but, it is hard to tell from a picture. Looks like something has been grinding away in there.
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There's certainly been some grinding of swarf going on, I'm convinced the body and rotors will be OK, I was wondering if there was anything to be gained by finding new covers. As you say hard to judge from a photo, the scratches on the covers are quite deep.
If they're all a bit scratched up I might leave it, if you think they're a mess I'll look for newer ones.
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It is hard to measure the clearance. May be easier to find another pump and fit a new seal kit. just make sure that there is no glass bead left in any oil ways. It is a sod to clean and that is why I never vapour a engine.
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I may get another pump for peace of mind, let me know when you get the seal kit in.
The pumps DK have for sale are unopened - they could be just as bad inside, so you are taking a punt unless they'll change them.
I just had a message to say the engineers have got the rotor and starter clutch off my old crank.
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Ensure the 3 o rings are new, 2 large outer ones seen in the pic, plus the smaller one that the rotor shaft goes through ( a bit of a pig to get out) if these are not in good order oil will escape from pump and loose oil pressure
Sent from my iPhone using Tapatalk
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As I said in PM I do have a spare pump but unsure of condition and model its off
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As far as the pump goes, it all looks good in there as far as rotors and body go, I just don't know what is 'normal' for the scratching on the endplates. certainly the one they took apart in the Haynes manual looks just the same as mine inside. I was hoping Trigger could say 'good' or 'scrap' but I realise its not that simple from a photo.
A replacement may be wise, but a bit of a pig in a poke as far as condition goes. Maybe I should stick with what I've got, with new seals.
I am all too aware that I haven't yet found a definitive cause of why the mains failed, but that probably points back to the kinked feed hose, which would leave no clear evidence.
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I've just been cleaning out the main horizontal oil gallery, once I'd manage to remove the end plug - IDK if mine's ben polished undersize, but the only spanner that would fit was that old Honda favourite of, er 1/4 inch Whitworth! Maybe its because oilways count as plumbing.
No glass beads or other nasties came out when I flooded brake cleaner up there, it ran out of the mains as it was supposed to do.
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Have you got the head and barrels to part company ?
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The head and barrels are apart, yes, but the barrels are still very much part of the upper crankcase.
I was getting perilously close to doing real damage, and I don't see why it won't go back together the way it came apart. It makes it more difficult, but not impossible, in race paddocks (and cars) bottom end issues are often dealt with like this to save time.
BTW your engine stand is turning out to be an essential. I noticed the first pages of the Honda manual shows a sandcast motor in something very similar.
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sorry, I meant the barrels to the crank case :)
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A busy day Sunday. I polished the cam cover at last, stripped the carbs for an ultrasonic bath and the choke linkage for a replate.
I also removed and stripped the oil pump. The rotors and their fit together are like new, with slight scuffing, but the endplates are badly marked up. Some scratches in the body but not much. Trigger, are these toast or useable?
(http://i34.photobucket.com/albums/d144/roycropper/IMG_1429.jpg)
I was building up some pumps today and have a chance to show you what a good pump looks like.
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Well the hiatus in this thread was due to me testing my engine building skills touring the north coast of Scotland on my Sportster, with its brand new crank, rods, cams and bushes. 1700 miles later, and no more noises than it started with. Here she is on Skye:(http://i34.photobucket.com/albums/d144/roycropper/IMG_1584.jpg)
In the meantime, Trigger has sorted me with an oil pump rebuild kit, and Ashely has kindly sold me his spare crank which turned up via courier this morning, in enough packaging to wrap an oven:
(http://i34.photobucket.com/albums/d144/roycropper/IMG_1727.jpg)
To my great surprise, as per the instructions on the Honda crank bulletin, when I tilted it to the light, I can see the scrawlings on the crank, AAAA a squiggle in a circle, then 4444. I need to check the rods for markings, and at the weekend we will use a calibrated mike from Ed's works to check all the measurements, but as the cases are BBBB it looks like I will need a set of green shells for the mains.
My 2 assistants who helped me pull the motor and I all wrote dates on the garage wall to predict the refitting date, Ed the engineer picked the earliest date and is quietly optimistic. Last night I dropped the carbs off with him for a go in his ultrasonic bath, and the choke linkages to get zinc plated. We were intrigued by the little sprung trapdoors on the chokes, I'm guessing this is to stop a backfire blowing the carbs off. Nothing that fancy on an Amal!
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Make sure the con rods have not ovaled, as you will be wasting new shells.
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Make sure the con rods have not ovaled, as you will be wasting new shells.
May still have rods off that crank if they are ! Isn't it wonderful packing cranks so courier doesn't trash them ! :'(
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I don't really understand why, but although the main bearings were all toast (shells and journals), the conrod bearings were all fine.
I will be using new shells, of course, to fit this crank, I'll try checking the rod big ends for roundness with my vernier calipers, though.
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I did not realise that the con rod shells were all fine. To that extent of wear to the crank case shells, I would of thought it would of picked up on the rod shells.
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On careful measurement the crankpins and shells had slightly ovalled, but the roads were still perfectly circular inside.
Ash, your crank measured up perfectly, all 'A's as you said, and as marked. Please pm me as to where to Paypal the money to, or whatever other way of payment you want, again a thousand (or 736) thankyous.
Now this is interesting- with a full set of A crank journals, and all As on the cases, (not Bs as I thought), you'd fit yellows. We checked the old crank and although the journals were too FUBAR to measure, this crank was also marked. AAAAA. However, a set of greens had been fitted. As we understand the crank bulletin, this would mean you have the maximum size journal, the minimum size hole in the cases, and a full set of greens fitted, which is wrong, and tightens things up by .005 or so - would this lead to a too tight fit that semi seized on startup?
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Glad it worked out for you mate. As I said my old mate Big Al had measured it up and he was apprentice of the year at the National Engineering Laboratory for 2 or 3 years running (used to go on the back of Midge Ure's BSA C15 to work) !! but I could only find the bit of paper with his measurements on for the one I am keeping. Bryan, Trigger & Oddjob are the sages on this, not myself, but I gather the old pro's just bang in GREENS anyway BUT tell the customer to run in very carefully. Maybe someone fitted GREENS and then thrashed it.
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It would not have seized, partial or otherwise, with those shells mate. I would just about guarantee bad oil/changes
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Ok, thanks for that info. A set of NOS yellow shells for the mains and greens for the big ends have been ordered from Yamiya750 in Japan, along with the oil seal for the crank, timing side. Last time I ordered anything from Japan (a JIS screwdriver) it took a month to come, in a ridiculously big box. Lets see how long this takes, in the meantime I shall continue to whittle away at scraping off the head gasket, delaminated but solidly baked onto the barrel, and I'll also do a valve regrind, and fit new valve seals.
The Athena gasket kit and plastiguage I bought off eBay arrived today. I have also polished the cam cover, which is why I wanted to take the engine out in the first place, before I realised there were crank issues.
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Yamiya is very quick delivery I think. They are very efficient to deal with. But I get mine in Japan and get someone in Japan to ship it for me as you get stung big time on import duty.
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B*gger, I hadn't thought of that, the parts were dear enough as it is. Also, if my new K1 seat, from Florida, was anything to go by, ParcelFarce bill you another £12 or so for the privilege of collecting the duty from you.
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Aagh! I tracked my shells from Japan to Manchester, today I got a latter from ParcelFarce, who have my package in there Manchester depot, but want me to pay £62 in duty, Vat and their extortionate £13.50 collection charge.
Today I have been mostly wet and drying my cam cover, I'd previously had a go at polishing it but that vapour blasted matt look is damned hard to get rid of in all the nooks and crannies. Later it'll get another dose of the polishing mop, I realised that if haven't done this stuff when the shells come, it's just going to hold the job up.
Later I might whip the valves out to see what the seats are like, and there's still plenty of well and truly stuck on delaminated head gasket to carefully scrape away at. I got some Loctite gasket shifter, but it doesn't seem to penetrate that deep, and I don't want to start scoring it with a knife in case I gouge the alloy.
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Jeez £62 how's much did the shells cost?
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It came to about £200 including carriage with the 10 main bearing shells, 8 big end shells, the crank oil seal, and I also stupidly added a set of 4 rubber float chamber gaskets in too, only later did I realise I'd paid way over the odds for these, trying to avoid the silly cost of buying the gaskets as a part of 4 'rebuild kits'.
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Seems a huge percentage of the cost of the parts, still that's the treasury I guess, legalised robbery.
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Unfortunately as soon as goods from outside the E.U valued at £15 or more, import duty becomes payable, then V.A.T. on the goods value AND the p&p costs, plus parcel farce's rip off fee on top.
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Goods over £135 attract a whole variety of different rates for different goods from different countries. It's a minefield. Best to try to stick under the £135 if you can and then it's just VAT and admin.
Mind you I have had two deliveries from Cruzinimage recently and both slipped through unnoticed. But I've always had to pay when it's come from the US.
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You will always pay the duty if you buy from Yamiya as they are squeaky clean on customs declaration that's why I always get my 'man in Japan' Chris to ship them for me. Lets face it a lot of those parts look like they are probably worth 2 quid in value not 200.
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I may have to take you up on that if I bugger any of them up, at least now I know I got the right shells. The day started well with plastiguaging the shells, I used green first but it squeezed to wide, another go with the red I should've used first, I got it to be 1.5 thou clearance imperial, .038 mill, within the manufacturing tolerance.
It ended up being a mixed day. The first knockback was finding the metal ring around the oil seal in the middle was well and truly stuck, ill take it round to the engineer bikers I know before I damage something.
The second knockback is far more serious- I didn't really appreciate that its one thing to undo the conrods in site with the barrels still on, another to get the caps back on without pushing the bolts up the rods, let alone start the nuts on the threads, all the time trying not to damage the expensive new shells. Suddenly I'm not convinced it's possible but I'll keep trying. I've got the two central rods on and tight, but I'm close but no cigar with the outside pair, I'll have another bash tomorrow.
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Well that was a disaster.
I managed to get the rods attached to the crank, lubed all the shells and put the cases together, all fine. Torqued up the main bolts around the crank, as I did when I plastiguaged (bear in mind I couldn't turn the crank then or I'd have ruined the plasticine) and guess what.
It's locked up solid. :( I opened it up again to see if any shells had moved or overlapped but no. I tried again, all moves until you nip up the first bolts, the 2 long center ones under the crank, then all was solid again.
I think I need professional help.
ETA: just a thought before I throw in the towel - I used lashings of redline assembly compound on the crank journals - given that the clearance was only 1.5 thou, could it be that the goop can't escape sideways and is causing a hydraulic lock when tightened up. Wishful thinking maybe but I could try again with most of it wiped off.
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Hmm sounds like you are having fun Dave. The crank I sold you definitely turned over OK in the engine it came out of and the main bearing shells all looked great. Have you tried lubricating the bearings and placing the crank in each half individually and rotating slowly to check that nothing is fouling? Also have you checked that you have matching top and bottom halves ( 2 halves should have the same stampings / markings top and bottom). I smell a bit of a rat that your original shells picked up so badly as it's very rare for shells to wear down almost to the copper like your original ones did, even if the wrong shells had been fitted. The 4-cyl 70's Honda crankcases are line bored in production so you can't mix top and bottom halves from other engines, like you can with Honda twins. Could it be that it's had chain damage and somebody has fitted another crankcase half?
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Adding to my earlier post ..in a situation like this I would post the detail of your issues on the USA site ... problem is on there that you can easily get your post buried because of the no. of posts, so keep adding your own replies or 'bumps'. Then if you don't get a response / solution after a few days, PM Hondaman with a link to your post. He usually responds by adding to the post and not a direct PM, which is the correct thing to do, as everyone benefits..... of course there is also Bryan, Trigger & Oddjob on here , who were in the trade and know a lot more than the likes of me.
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Have you measured up the crank to make sure it is straight ? Can't remember how far you are away from me, as I find it hard to give a 100% comment without it in front of me.
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Thanks for your comments, I don't want to ask our American cousins just yet, from past experience with US car forums, they'd probably turn it into an oil thread :) I have read the relevant bits of Hondaman's book very carefully, though.
FWIW I have a theory, though its going to be hard to prove / measure.
I was thinking, like Ash, that the cases might not be a matching pair and so the line boring is screwed up. However, both are stamped at the back with an 'M4', are there any other marks that would appear top and bottom?
It's too much of a coincidence that I got a freshly rebuilt engine, everything inside like new, with completely FUBAR mains shells, and absolutely nothing else wrong. Replace shells, torque it up and its solid. Maybe someone, a long time ago in South Africa, got to that stage before and either 'made' it turn with a big bar on the crank nut, or slackened things off a bit and flogged it quick, or even just trailered it to shows or stored it from then on.
As far as I can see the crank is straight and central, I just unipped the crankcase bolts , freeing it up again, and turned the motor over with a ratchet on the stator nut. As I did, I watched the crank at the ignition end turning perfectly in its new oil seal - if anything were bent you'd expect a slight wobble, and I trust Ash's judgment. It all turns over lovely until that last nip up to 18ft lbs.
Here's my theory. Remember how we were surprised that there's no oil stains, or any sign of that yellowish coating that the cases usually have? Well its ALL been blasted inside, we don't know with what media, but it was agressive ( it turned the polished forks and engine cases matt and rough to the touch -I Just read that vapour blasting doesn't, but IDK) INCLUDING the mating surfaces where the crank cases meet, AND where the crank journals are, look here:
(http://i34.photobucket.com/albums/d144/roycropper/IMG_1419.jpg)
(http://i34.photobucket.com/albums/d144/roycropper/IMG_1417.jpg)
Stupid muppets, that's a precision surface you ruined, critical to the fit of a crankshaft that is fitted to half a thou tolerances! IIRC that includes the bearing housings as well, I have no photos with the shells out, and its another teardown to look, but I will.
here's what we should have - a machined surface done at the same time as the crankcase mating sufaces, BEFORE the cases are line bored for the crank.
(http://honda-cb750-s.456789.n3.nabble.com/file/n4036846/IMG_0979.jpg)
The perfectly circular line bored holes now aren't, if metal is removed at the join by media blasting they will become ever so slightly egg shaped - fine front to back but tight top to bottom. When I plastiguaged the mains I did it at 45 degrees to see clearly, I may get a different result at the top, I may have another go with a few threads in different places to see if the fit varies.
It would also explain why the mains were 100% toast but the rod bearings were fine, which was totally unexpected for an oil supply failure.
If this this the case (no pun intended) shimming wouldn't work, if you got the clearance right the case's mating surfaces would leak like a sieve. Re line boring by a precision engineer could work though, it needs to be 39.000mm, I don't see why the horizontal measurement would have changed for the worse, and if the cases are a tad closer together the other measurements can only have reduced.
The only other solution would be to find a good second hand set of K1 cases. There are later ones on eBay, but I'd be very wary of the subtle changes to the cylinders and gearbox in later models causing more hassle down the line.
The best course of action is to strip it down and try to measure the holes for round, whatever I do the huge elephant in the room is the fact that the barrels won't come off - they're going to have to whether they like it or not, only God knows how!
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The numbers to match the crank case are a letter then 1,2 or 3 numbers (C190) as a example, these are located on the flat surface at the back.
When you have turned the crank, has it marked the shells in any way ?
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That might work Oddjob, I'll try it. There is the matter of the lower part of the rods being in the way, though, as the rods and pistons won't come out (in either direction) without the barrels being off (I have tried). It does sound doable with careful preparation though.
I've been (instead of doing some work) reading up horror stories such as a guy who had an vintage aircraft engine blasted (and saved by re-engineering, including line boring, but they are *&%$ expensive things) of course with those if you later break down you don't just walk home, you fall out of the sky first.
I just found this nugget - oh deep joy!
That being said, I will caution against it for a more unlikely reason: future disassembly. A matte surface will bond with well over double the bonding force of a smooth surface. If you've ever removed a 20-year-old gasket from a machine, you know it's a bear to do. Cleaning the surfaces afterward is cumbersome at best. You make those mating surfaces matte prior to assembly and I would dare say those pieces are bonded for life.
:'( :'( :'(
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The bores are like brand new, and you can make the rings pop out, but the bottom of the rods (where the big end bolts are) are wider than the liners.
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On another note, removing the barrels. How about this, get a thick piece of wood. Cut it so that it fits where the crank would be but is pressing against the liners of the barrels. The wood would need to be thick enough that the lower casing won't quite fit, then bolt the casings together, the pressure from the bolts should pop the barrels off, you only need it to break the seal and they'll come off anyway. OR use the same piece of wood as a drift to protect the liner and hit it with a big hammer. Maybe cut a circle of wood just bigger than the liner so as to spread the blow around it.
That may push the liners out Oddjob
If the liners are removed, then the con rods will go through the liner holes.
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May have some F1 or K7 cases but not a lot of use to you. Neither are the ones unstamped that Freddie has as I think they are for a later engine (ask Trigger). Your best bet may be DK and they are not a million miles from you.
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Ive not completely given up on these cases, that guy did get his aircraft engine re line bored (and AFAIK he didn't fall out of the sky later), I suppose the question is how accurately can it be done, there is a good engineer round here who polished a couple of thou off the crank journal of my Sportster to fit a new crank to my existing cases' roller main bearing. If the cases were torqued together to spec it would be interesting to measure up at least, if its locking up then the journals cant be oversize. I don't know yet whether the shells are still Ok, they were last time I saw them. If I'm really lucky I'll get a set of AAAAA cases!
The proof of the pudding will be once its all stripped down again and when/if I get those barrels off. In the meantime keep an eye out for K1 cases, though.
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Well that's one problem solved.
Rather than pussyfooting around tapping with a rubber mallet and a 'mustn't leave a mark' attitude, take a dose of contempt, a decent size hammer and a big screwdriver to use as a drift, and behold, I've broken the base gasket seal, and ironically, not left a mark.
I've just popped in for the manual as the camchain tensioner is in the way of pulling the barrels off - it's going to make the stripdown a lot easier without all the keyhole surgery approach.
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Feeling for you Dave. I blasted my 250 engines only the outside but only after totally sealing everything on a fully assembled set of cases with no internals fitted and then pressurizing the inside to check for leaks.
How about this for an idea ..a few of us must have quite a few old shells lying about, that may not be too worn. How about experimenting with them to try to ascertain where you have lost 'clearance', then you are not going to fk up valuable new shells. This is going to be totally frowned up on here but why not get some pieces of copper foil and make little gaskets for the centre bearing mating surfaces. Put your crank in but only nip up the centre bolts and see if you can regain your clearance, using Plastigage to measure it. I think line boring would be quite hard but it depends on who you know and what equipment they have, definitely cheaper to get replacement cases if you had to pay commercial rates for that job.
If you find they blasted the bearing housings that the shells fit into then IMHO I would think your cases are toast.
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It's a real shame to get caught into something like this when you just wanted a nice bike to ride. I does look like you are right regarding the loss of tolerance to the mains though. I know when we are involved in stuff of this age there are problems to be taken on but you'd not anticipate something so obscure and fundamentally wrong.
There is a process other than line boring that could realistically get those cases back which is engineering scraping. It was routinely done to get bearings into tolerance in some fields particularly when people would have been making up soft bearings for large machinery. It involves using something like a correctly sized mandrel to check for high spots with engineers blue, then physically scraping the high parts away and re-checking until the hole accurately matches the mandrel.
To expand on your method Ash but instead the opposite direction, you could linish the back of the shells with a very fine grit paper while miking them to relieve the space over an arc at the deepest part of the shells then check crank fit in them with engineers blue to bring them into tolerance and roundness.
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Thanks for your replies, here's a couple of pictures from the garage last night, the cases are stripped right down now, though I just have to remove the transmission.
Every picture tells a story:
(http://i34.photobucket.com/albums/d144/roycropper/IMG_1746.jpg)
There is a slight lip at the back corner on each side of the barrel overhanging the cases, A smart whack upwards each side did the trick - daylight at last!
(http://i34.photobucket.com/albums/d144/roycropper/IMG_1747.jpg)
You can see that the pistons are stamped '25' - the motor had just had a rebore, great news and it explains why there was no sign of wear in the barrels. Clearly someone spent a good deal of money on this bike, only for it all to go breasts upwards over such a tiny issue, resulting in most of the new stuff, which included brand new rims and spokes, being virtually zero miles, because of the crank FUBAR. Thats why its well worth doing right, IMHO.
I would like to save these cases if I can, for all the trouble the 'whatever' blasting has caused, the external finish, polished and then painted (I didn't realise until I chipped it trying to prise the barrels off) is super, and the cases look like new. I'd struggle to get another set that good, particularly as they would definitely not be going anywhere near a basting cabinet! IDK if the threads were masked, or recut, but they all look fine, unlike a set of BSA cases I once bought at an autojumble, when I was young and stupid,that had been blasted and turned into scrap.
I'd rather not go down the packing route, Ash, I'd prefer sound engineering to trial and error, and also the packing would have the effect of pushing the crankcase halves apart unless you made a copper gasket for the whole of the crankcase - It could leak like a sieve, not support the transmission bearings properly, or if it torqued down OK all be under stress. That reminds me, as Hondaman says, if you can line bore a 'seasoned' motor, that has already gone through many heat cycles, you get a smoother motor than one that was line bored when it was virgin metal, something that race engine builders use to their advantage.
The bearing carriers aren't factory finish any more, but very smooth. Its the centre line measurement that has been messed up - removing some of the circle has caused it to become slightly oval - they should be possible to line bore out to spec, as they are tight not slack - you can make a hole bigger, but not smaller! ;)
I could have a go at scraping as suggested by K2-K6, at virtuall zero cost, but trial and error with 10 shells to go at sounds a bit of a mare, and it would only take one error.
According to the HMC crank bulletin, bearing support 'A' tolerance (which would let me use my yellow shells with Ash's AAAAA crank) is 39.000 to 39.008 mm. If necessary the bore can be as big as 39.024, but obviously thats a set of different shells.
I'm going to send an email to Quasar engineering in Stockport http://www.quasarengineering.co.uk/ who fine tuned my Harley crank for not a lot of money, see what they quote / think before I make any irreversible decisions.
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It was only a suggestion Dave.. personally, I would get replacement cases but if you want to preserve numbers then that's possibly not the route to go. I assumed it was only the centre 'pillars' that were nipping up the crank so small bits of 1 thou copper foil may have just confirmed that the problem is mainly on those and not the outers, but you could probably ascertain that anyhow from a decent bore gauge measurement, wiith the crank out and the cases bolted up.
I checked the cases the crank I sold you came out of as below and apart from one outer half, all the shells are still there if you wanted to try used, not particularly worn SH shells to check whatever method you come up with is satisfactory without trashing 100+ quids worth of new ones.
[attachimg=1]
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I would also bin those crank cases and seek a replacement. If the bearing surfaces are damaged, then all bearing housing will be beyond spec, this will include bearing and oil seal housings.
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Given the note you found that you posted earlier in this thread about a matte surface bonding with well over double the bonding force of a smooth surface, and the fact that the blasting removed enough metal to give the problems you have had, if you keep the cases would the first step be to get the mating surfaces skimmed to get them flat and smooth?
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What Trigger says is food for thought, as he knows more about these motors than most. Will the couple of thou that uses up my crank oil gap have the same effect on a the housing of a large ball bearing or a rubber seal though? There are no signs of trouble with the gearbox and final drive bearings, no witness marks or roughness. I do take your point though.
Anyway, until something else turns up, these cases are what I've got.
Yes Chris, I'd like to get the mating surfaces lightly skimmed, but then again every thou makes the problem worse.
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I would also bin those crank cases and seek a replacement. If the bearing surfaces are damaged, then all bearing housing will be beyond spec, this will include bearing and oil seal housings.
Agreed but depends if blaster has blasted centre bearings more than outer ones (smaller area too), which I suspect, as its only when he torques centre bolts down it nipped up or was I wrong on that ? Best thing is to clamp it all together with no crank etc and measure the bearing bores for ovality IMHO
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There is very little disturbance to the bearing housings as far as I can see, they must have been gentle there. The trouble is the metal removed from the centre join as far as I can judge, there is no trace of the original machined finish. :(
Ive sent Quasar this email earlier today, we'll see what they think, they are only 9 miles away so it won't hurt to get things accurately measured, at least.
Hi, I have a 1971 CB750 Honda four cylinder classic bike.
I bought the bike already restored, but with damaged main bearings. I have changed the crank for another, known to be in very good condition, measured the journals with a micrometer and fitted the correct shells. When I tourque up the crankcases, the crank locks up, just as the final torque setting is reached. I believe that the problem is that previous media blasting of the cases has removed a few thou of alloy from the crankcase centre joint, meaning that when the cases are tightened up the crank journals are slightly out of round, nipping up the required oil clearance. I have the Honda spec measurements for the bearing shell housings we are talking about a range between 39.000 and 39.008 mm I.D. for the shells I have.
If I brought the cases to you, (I am in Stalybridge) could you measure the crank journals' internal diameter for this, and if possible line bore the journals back to spec?
What sort of cost are we looking at?
The alternative is to use another set of cases, but I would like to save the originals if I can.
Thanks, Dave
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Yes Chris, I'd like to get the mating surfaces lightly skimmed, but then again every thou makes the problem worse.
Agreed, and it would be more work and more money.
But can you be satisfied that the surfaces as they are are still 'true'? As there is no way of knowing exactly how much metal the blasting removed it is quite possible more has gone from some places than others. Maybe get an opinion from Quasar, to be sure this wouldn't be a problem.
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Two things
(1) a large piece of plate glass from a glazing firm and some very fine compound will check if the case joints are flat
(2) Back when i did a lot of Ford engines if a big end knocked it was common practice for the rod end to need resizing as they ovaled
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It was only a suggestion Dave.. personally, I would get replacement cases but if you want to preserve numbers then that's possibly not the route to go. I assumed it was only the centre 'pillars' that were nipping up the crank so small bits of 1 thou copper foil may have just confirmed that the problem is mainly on those and not the outers, but you could probably ascertain that anyhow from a decent bore gauge measurement, wiith the crank out and the cases bolted up.
I checked the cases the crank I sold you came out of as below and apart from one outer half, all the shells are still there if you wanted to try used, not particularly worn SH shells to check whatever method you come up with is satisfactory without trashing 100+ quids worth of new ones.
(Attachment Link)
I 2nd Ash with this, torque the empty cases and get an engineering firm to precision measure the case bores. You may only be able to measure the outer bores accurately enough but that will do. If they measure small or oval your cases are toast and anything you try will not be acceptably accurate unless your an old school engineer with amazing skills. Sounds to me like the case blasting has removed material from the mating faces, and thousanth of an inch on each case would be more than enough to cause your problems. Good luck with it.
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I'll see what the engineers say in reply, cases have been linebored in similar circumstances, but one worry would be the deck height of the cylinders, you would effectively move the pistons nearer to the valves! - in fact you already have by taking metal of the crankcase face.
Ash, you don't think Freddie's unstamped cases would be any good? He doesn't say what year they are, though I take his claim that they'd fit all years with a big pinch of salt, can anyone shed light on this?
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I'll see what the engineers say in reply, cases have been linebored in similar circumstances, but one worry would be the deck height of the cylinders, you would effectively move the pistons nearer to the valves! - in fact you already have by taking metal of the crankcase face.
Ash, you don't think Freddie's unstamped cases would be any good? He doesn't say what year they are, though I take his claim that they'd fit all years with a big pinch of salt, can anyone shed light on this?
I have answered the question many times about these unstamped cases but, not on a forum. I can see that these case's are a late shape and would be suitable for a K3 to K6 .Possibly a F1 if I could see the crank case breather.
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If you want to spend some time before going to an engineer here is what I would do:
Fit all the knackered shells then replace 1 journal at a time with the new and torque up to see if the crank locks up checking all journals individually.
If only one journal locks up the crank try fitting the shells for smallest case and biggest pin then try again, if all lock it up i would look for different cases or a complete engine using the rest of the bought engine as spares.
As somebody else said the gearbox bearing clearances will be wrong as well and you will be clamping them too tight, and whist they are robust steel cages I don't think it's a good idea.
As too altering the piston/head clearance that is minimal considering you can skim both head and cylinders
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Been thinking about this for a few hours now and have come to the conclusion that if it was mine (although I did previously say to get them measured) I would just replace the cases. You can waste days playing with what you have and waste money at the engineering shop for no gain. Re line boring them is not really an option unless they are one off historic and valuable. The cost alone will stop that idea dead in its tracks. I recently rebuilt a CB750K3 for MCTID (Alan) who had damaged cases, and when I put out the call for replacements there was loads available. Thats the way I would go. Cheers.
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I don't believe there are loads of K1 cases out there to be had...I know at least a couple of other people after them but I agree I would replace if at all possible. There would always be a nagging doubt about it but it's an engineering challenge for sure. My main fear would be thermal contact between the shell and the blasted surface of the crankcase. The only thing that would sway me is if the those surfaces are smooth enough and , after measuring you find it's only the centre bearings nipping, then my idea of a shim foil to make those bearing clearing surfaces correct. Freddie has had some cases for sale on eBay for well over a year and they are unstamped. Trigger tells me they are not correct for a K0 but not sure which model they would fit. Sometime I am going to get my man in China to replicate some Honda stamps, so you could possibly and legitimatelly stamp with original numbers. You could make Freddie an offer if they are indeed suitable.
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See Trigger's comments above re the unstamped cases, they appear to be a non starter. A friend of a friend I met at Stafford has a ton of CB750 bits, a text has been sent to see if he has any K1 cases.
As all 10 journals were so FUBAR, I don't think it's just one pair. That said I have plenty of time until more cases turn up, and lots of Plastiguage.
Looking closely last night, the shell carriers are very smooth, I'm pretty sure there's a layer of silver paint, how thick could that be? It's got to be worth trying to strip it off and re measuring, it could be stove enameled/ powder coated, I really don't know, it's that kind of finish. If so, how to get it off?
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Methylene Chroride based paint stripper but be quick to remove once it softens and flush with solvent/soapy water. If powder coat , you will have to burn it off IMHO
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Unfortunately when I Google that, the word 'free' appears after it in every product, it seems the Eu have banned it for killing people. I'll have to see what strippers I can get down the DIY store.
Burning sounds scary in case I distort the cases, I guess a careful experimental wafting with the blowlamp if necessary.
I do wonder if I'm on to something, though, especially if the journals turned out to be dead round, I won't know until I measure, I'll see if my mate can get an internal mike from work. I'll have a close look at where the paint / whatever got chipped to try and get my head around how thick it is.
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This stuff was mentioned in a previous thread, says it is based on Methylene Chloride.
http://www.ebay.co.uk/itm/Paint-Stripper-1-litre-Restorations-Car-Bodywork-Metal-Remover-Wood-Furniture-HD-/291808738692?
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The shell carriers should not be painted. They should be clean smooth aluminium. The inside of the cases are painted to stop the ally being porous. Maybe after blasting they repainted over the lot? That would for sure lock the crank, but didnt you just Plastigage the shells and they came out good? Weird things happening here?
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Be careful with anything with caustic soda in it as it will attack the alloy. If you need locally go to an automotive paint supplier.
Agree with Roy though .. IIRC you Plastigaged it statically and it was OK > Something not right there.
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Thanks for the link Chris.
I did plastigauge, Roy, but at an angle of about 45 degrees from the top, as it was before I got the barrels off and I was performing keyhole surgery. I'll have a proper go on Sunday, the next chance I'll get, doing it across the top, also I have ordered a loan of an internal micrometer from Eddie's works.
Maybe I've been barking up the wrong end of the stick, as my dippy missus would say. What I assumed was a vapour blasted finish turns out to be paint, powdercoat, I don't really know yet. They must have used some sort of blasting to get all the chromate finish off the inside of the cases, as its all rough, but the rest maybe they just painted, or blasted then painted, IDK. Maybe they resurfaced the crank joint, as that's smooth, maybe not, we might know when we measure the journal bores. Certainly you can see here the smooth but painted, not bare alloy, journals:
(http://i34.photobucket.com/albums/d144/roycropper/IMG_1749.jpg)
The moment of truth came when I noticed the small patch where it has been rubbed off on the carrier on the left - a lightbulb moment.
The previous photos were all taken with my crappy mobile camera, however I do have decent cameras and lenses, so I dug one out. Here is a closeup of where I have chipped the paint while trying to lever the barrels off (dog rough, I know, but I was getting frustrated by then).
(http://i34.photobucket.com/albums/d144/roycropper/PA060194.jpg)
I should have put something there as scale, but the photo is of the leading edge of the upper case, you can make out 2 of the reinforcing ribs.
Anyhow, you can see the thickness where it has chipped, and for a circular bearing housing we are looking at twice that. It only needs to be a thou thick to steal my 2 thou clearance, though the positive plastiguage result is still a mystery, as it would be uniform around the bearing.
Maybe its a combination of two cockups, we may know more after Sunday when I will be mostly measuring. If it were a paint problem though, that could be good news, as it can be removed from the gearbox bearing housings as well as the crank journals. We'll see.
ETA: Bought the paint stripper, got a mask and safety specs (not before time!) while I was at it. :)
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Right, news from the front, which means theres at least a good chance we can save the cases by getting this &%#*@ silver paint out of the journals.
Ed the engineer turned up with his works' digital bore guage, accurate to 0.001mm, a lovely bit of kit, about £1,400 a pop. We could only get at the two outermost journals though. I had taken the crank and shells back out, cleaned everything, and torqued the cases together back up to 18 ft lbs.
Basically, the holes are circular :D but measure only 38.955, they should be 39.000 minimum, all the Honda shell options are for this (A, as originally stamped on the cases, is 39.000 to 39.008mm) and above.
The difference, near enough .05mm, is 2 thousanth of an inch, he thinks its quite feasible that this is the 2 layers of 1 thou thick paint either side of the journal. I showed him the patch where it had chipped, in the above photo, and he could catch his nail on it.
When I get the paint stripper I'll get the silver out of all the bearing housings, and he will return next week with the same guage. I showed him the photo I took of my plastiguage attempt, he pointed out that it was squashed almost to the max for that colour (red), the proof of the pudding will be when we try again without the paint. Most people say green is the one to use, though I'm a bit confused as to why, I have both.
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A brief update, I decided I needed to know if I needed another bottom end before I went to Stafford tomorrow morning.
I donned my mask, safety specs ( soon gave up with these as they kept misting up, and I was hardly sloshing the paint stripper around), and on the advice of Ed I wore double gloves. Once I'd scraped the bulk of the paint off I could almost wipe it off with the Loctite gasket remover, I noticed when I was scraping away the base gasket that it was shifting the silver paint, I don't know what's in it.
I got the paint out of all the main journals, and all the gearbox bearing housings while I was at it.
Ed has flown off to Korea, his job's like that, so I couldn't borrow the bore gauge again. However when I spoke to him last night, he suggested I just put the crank & shells back in, lube everything & torque it up, if our theory was correct it would work, if not the cases are scrap.
I was nervous as I tightened the bolts, having been here before, but I kept checking as I tightened each bolt. I finally got the last one up to 18ft lbs, and guess what? It still turns!!!
Jobs a good 'un, as we say up here, and I know the rods shells are right, so hopefully no more dramas, though I'm not in a tearing hurry.
Who would have thought that an uneccesary layer of paint could wreck a fresh engine? I reckon they realized there was a problem too late, and made it turn over.
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Nice result in the end Dave .. are you Plastigaging again or just 'going with it' ?
Don't think you would have found any K1 cases at Stafford. I did see the same bottom end I saw a week or so back at Newark but it's a very late engine with weird numbering
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I decided today not to bother with Stafford show, seen most of it before and nothing I need to buy right now, and spent the day in the garage instead :)
I did a plastiguage check, 1.5 thou imperial, within spec.
I built the bottom end upside down, into the top case, it was much easier to align the gearbox bearings with the half rings etc, got the crank in the chains, rods on and the cases together, checked I had 5 gears too. Then after I torqued the crank bolts up for the hundredth time I checked Hondaman's book for the torque setting for the small bolts. Only then did I notice his warning that it's easy to put the large final drive gear on the layshaft the wrong way round, which wears it and the gear next door out. Earlier it had been rolling across the garage floor, and I realized the was a 50/50 chance of this :(
I decided to split the cases again before the sealant went off. I'm still not sure which way round the gear is, but I'd rather redo it than get it wrong. Hopefully the drawing in the parts book may help, but I'm done for today.
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Another update, this is where I'd got to on Monday evening.
(http://i34.photobucket.com/albums/d144/roycropper/PA170001.jpg)
There will now be a delay while I scrape off the remains of the base gasket from the barrels, as it was very well stuck on, which is why I couldn't get the barrels off. I'm about to nip to B&Q to buy a couple of large hose clamps to use as ring compressors - you polish the burrs off the inside, as per Hondaman's book. Edit - got ones that were smooth inside, no serrations, £2.54 the pair!
I'm minded to fit the plug to the end of the oil gallery, and fill it through the oil pressure light switch hole, so the mains have some oil. Whether it will slowly drip out, I'm not sure. I'll pick up the oil pump body later, they've got the central seal out and pressed the new one in.
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The centre seal will come out easy with a bit of heat ;)
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Ian got it out by jamming a twist drill in it, I'd tried heat but only suceeded in burning myself. The pump is rebuilt, primed and back in place with all the new seals and springs which you sent me.
The barrels are back on (I couldn't resist fitting the new damper rubbers I bought from RGP750 too), and the clutch cover, I was going to put the mousetrap that changes the gears back together last night, but the stop plate that goes on first is missing the tag that goes into the selector rod to stop it turning. I ordered one from DS today, he gets them to order.
Next I'll have a look at the head, more gasket scraping off to do, also I want to whip all the valves out for a check, number 3 exhaust has been running hot, I want to see if the seat is OK, though I suspect the old rock hard carb rubbers as the cause (I've got new ones). I'd like to measure all the springs for length too, although they might all have been new when the motor was originally rebuilt, I wonder what 10 or 20 years standing might have done to the ones that were compressed.
I'm posting to make a quick query, I know that NOS Honda head gaskets are preferable to pattern ( which explains all the single Athena head gaskets on eBay), but where the *&^% do I get one? If you don't want to reveal your source publicly, you can always pm me ;)
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Should be able to get genuine Honda head gaskets from CMSNL. But be warned, they're almost £80 a pop...!
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Ye Gods, one hundred and two of our earth pounds with VAT and carriage. :o
Suddenly the US ones with horrendous postage seem worth checking out. Are the Athena ones that bad?
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Graham's the man to ask....
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I did that, and rather than skimp on a job I only want to do once, I have bitten the bullet and ordered the real thing from CMSNL.
Ouch!
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Out of sequence, as it's going back together now, but here's the layer of paint that killed the crank by stealing the clearance - I took this after scraping away half the paint off the journal, having softened it with the evil stripper, and yes, I was wearing a mask. I had to be very careful not to remove any alloy or otherwise b*gger up the original surface, but I think I did a good job.
(http://i34.photobucket.com/albums/d144/roycropper/IMG_1754.jpg)
Here's what was going on in the kitchen yesterday, while the wife was away, more gasket scraping going on here. The teaspoon made a good scraper for the carbon in the combustion chambers, after I softened it with the gasket remover. ;) Later I put the valves and springs back, after lapping them in. Ive still got to have a go at getting the oil jets out, or Trigger will tell me off, but then the head can go back on once they are cleaned out.
(http://i34.photobucket.com/albums/d144/roycropper/IMG_1760.jpg)
The genuine Honda head gasket just turned up from Holland, via UPS, in a huge box. As Trigger said, it's strangely sticky, but I've put it back in the packaging for now, as it looks very fragile around the middle camchain slot. I don't want to mess it up, I assume from the price it has a layer of 24 carat gold in the middle.
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Yeah I've had 4 of the genuine Honda Head gaskets in as many months. Bloody bloody expensive....and bloody bloody sticky.
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Thats why they are a bugger to scrape off
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Another very good tip for anyone doing a rebuild, or just doing any head work.
The genuine Honda rubber "O" rings in the head that create the oil seal were found to be to thin, hence many of these bikes had leaks from the head...to stop this happening you can buy the same Diameter O rings that are slightly thicker [1mm]
So that when you torque the head down it does create a proper seal where as the stock O rings did not , this was a fault Honda never cured or modified.
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Well, the motor went back in today, no pics yet until I'm on the desktop PC. :) the same two mates that helped me get it out came round, it was fairly straightforward. I won't get a chance to do any more till Sunday, my first priority is going to be getting oil pressure before carbs, pipes etc go on.
I'd had a drama with the ignition timing yesterday, the new Honda points on pots 2-3 would not gap small enough, and setting 1-4 correctly would not let me get the other pair opening properly. I remembered reading that there are two OEM suppliers, and wondered if I was mixing a backplate from one with points from the other. Anyhow I refitted the original points, which were in as new condition, and it timed up a dream! :)
Once I'd got the engine bolts done up and the oil filter on, I put her on the side stand (still an alarming angle) took the oil gallery plug out and squeezed half a litre of oil in. That will put some oil the crank's way and give me a head start filling the filter when I start kicking her over, once I have the tank and oil lines back in place. Of course the proof of the pudding will be getting the oil light to go out, then starting her for the first time. I remember how nervous I was firing up the Sportster after her crank change earlier this year, but once run in I set off for the North coast of Scotland, no worries.
It does look good, at least I've got a polished cam cover now, and some oil pressure, hopefully. Thanks to all that have helped, especially Ash and Graham.
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Another very good tip for anyone doing a rebuild, or just doing any head work.
The genuine Honda rubber "O" rings in the head that create the oil seal were found to be to thin, hence many of these bikes had leaks from the head...to stop this happening you can buy the same Diameter O rings that are slightly thicker [1mm]
So that when you torque the head down it does create a proper seal where as the stock O rings did not , this was a fault Honda never cured or modified.
If you use a O ring 1mm thicker it will not fit in the recess or the hole in the gasket as it is a 16mm hole. The OEM O ring is 11ID x 2.4mm, 1mm thicker will give you a overall measurement of 17.8mm :o
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Maybe he meant he still uses a 16mm but it's a 3.4mm thickness rather than 2.4mm thick? That would result in the 11mm ID being reduced slightly as when it squashes down it will spread a little more, don't expect that the ID is that critical though.
Very critical, as it is a oil way. On the F1 Honda still used 16mm ID but, put dowels and sleeves to update the gasket seal.
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[attachimg=1][attachimg=2]
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I think you time machine to get part number 12020-300-305 Ash ;)
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I think you time machine to get part number 12020-300-305 Ash ;)
Just buy quad rings . in Viton
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I think you time machine to get part number 12020-300-305 Ash ;)
Just buy quad rings . in Viton
Yes Ash, but will not fit the OEM head gasket that CMS sell ;)
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Use later gasket part of NB gasket set or I know a sandcast guru who just used 'O'rings from RS. He fitted this arrangement on the 750K1 that UK Pete got off him, prior to selling him it . He did tell me the RS part number in an email somewhere. Will have to ask Pete if it panned out OK ITO oil leaks/head sealing.
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Another very good tip for anyone doing a rebuild, or just doing any head work.
The genuine Honda rubber "O" rings in the head that create the oil seal were found to be to thin, hence many of these bikes had leaks from the head...to stop this happening you can buy the same Diameter O rings that are slightly thicker [1mm]
So that when you torque the head down it does create a proper seal where as the stock O rings did not , this was a fault Honda never cured or modified.
If you use a O ring 1mm thicker it will not fit in the recess or the hole in the gasket as it is a 16mm hole. The OEM O ring is 11ID x 2.4mm, 1mm thicker will give you a overall measurement of 17.8mm :o
Well it worked on mine, & if I remember right Steve the bike builder who specialises in rebuilding the sohc engines, he bought the washers from a local shop that supplies O rings for all sorts of applications, he said they are the same diameter as stock but slightly thicker/deeper, I am sure he said 1mm...any how he has never had a engine back with an oil leak from the head or anywhere else.... ;D
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There is an obvious split between people on forums. As such I am deffo in the 'hobbyist' camp so don't take anything I post as here being gospel or always personally tried and tested. All I can say is that where bikes are concerned & not being in the 'trade' ... I have NO trade ;) secrets. If I have any info,tips, cheapo sources etc I will share on here 100%, as I don't earn my living from it (thank God).
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Get a room you guys, or an O ring thread ;D
Anyhoo, I used the O rings from the Athena gasket set, they seemed to fit fine, we'll see when I get her running, though.
Here's the motor on the bench, ready to rock, shiny cam cover looking good. Apologies for the Murkovision, the inside of the phone lens gets dusty in my pocket somehow, I sent it away to get cleaned a while back, but its getting foggy again. I have proper cameras, but tend to keep them away from oily fingers.
(http://i34.photobucket.com/albums/d144/roycropper/IMG_1765.jpg)
After Leigh and Ed turned up, we chucked it in and checked the dates we had written on the wall, on August 3rd when it came out, predicting when it would go back, Leigh's was 3 October, I was 1 December and Ed was 1 January 2017, so I win. Leigh accused me of sitting on my hands until victory was assured.
(http://i34.photobucket.com/albums/d144/roycropper/IMG_1766.jpg)
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Looking lovely, well done.
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I'm confused. How much turning over is necessary to fill the oil filter up from empty?
I fitted the oil tank & hoses, and put some oil in the tank. Many kicks later and a couple of spins of the starter, no oil had made it up as far as the gallery, never mind the oil light going out. I dropped the sump and the oil I'd just put in, and reprimed the oil pump. All appears fine with the pump, I don't really see how I could put it together wrong - (unless you know different- Trigger?).
Refitted, refilled, still nothing.
Maybe I'm being impatient, it's a big filter housing and tiny chambers on the feed side of the pump, but I'm paranoid about turning a dry motor over too much. Will I only get pressure when I start her up?
ETA: I found a similar thread on dot net, it turned out OK in the end. http://forums.sohc4.net/index.php/topic,101556.0.html
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These are a bugger to get all the air out of the system. I find filling the pump with Vaseline works as a very good prime. I would not try to push the button just yet, keep kicking it. When you built the engine back up, I hope you used Graphogen or the equivalent.
Another good trick is to take the oil pressure switch out and with a little funnel, fill it with oil.
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Even when you work on them normally in servicing them after the filter is changed and you've filled the oil tank with new oil, then you can see the tank level drop by something like the volume of the filter and that's without any of the engine galleries being empty.
It's a big worry with any engine if it doesn't appear to be building pressure, and always a bit of a nail biter as to whether to continue turning over or investigate.
All things being in place it still takes longer than your thinking allows you to be comfortable with.
I always use (as Trigger states above) Graphogen for all plain bearings when building an engine, the principal difference from just oil is that is stays coated on the surfaces even if there is a long period between building and using the motor. It will prevent any pickup with the bearings until the oil arrives.
Presume you have the spark plugs out to reduce crank loading?
Could try tipping on its side to fill the gallery via the plug with oil. I've never tried on one of these but you could also raise the rear and fill the oil filter housing without oil also and bolt it back on with it filled as much as possible and the filter as level an you can get it.
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I had the same problems with mine after a top end rebuild http://www.sohc.co.uk/index.php/topic,1573.msg1729.html#msg1729
This was what I said at the time:
Took a long time to get the oil pressure light off, I put one litre of oil in the tank and one litre in the cam cover, it took a long time for the oil light to go out, so long that I started to suspect the oil pressure switch, but a look into the cam cover showed no sign of oil spraying around so I carried on. The oil light eventually went out, then I waited a few more minutes turning her over until I could see oil spraying about in the cam cover. Plugs in and she fired up on the second push of the button.
Cheers
Dennis
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Judging by the many threads on here and dotnet, it seems we all go through this worrying dilemma every time a CB750 is rebuilt. If we couldn't see we wouldn't worry about it. None of these threads ends with an expensive clank, so it looks as if ! Once I get carbs and pipes back on, I just have to start her up and anxiously wait for the red light to go off.
I did use assembly lube, I'm glad I did now, I just never thought it would take so many turns before oil came into sight.
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As I said, do not push the button. Even if the oil light goes out, this may mean that there is no oil to the top end, as the switch is at the bottom and not the top. You need to remove the tappet covers to see the oil at the cam first. There is a member on here that did fire start you bastard in to the carbs and press the button until he realised that the oil had not circulated the engine and the engine was toast >>> http://www.sohc.co.uk/index.php/topic,10867.0.html
Two out of ten engines that arrive in my workshop are damaged due to oil not circulating after the owner has built the engine. So keep kicking unless you know that you have not left a O ring out and the pump is working 100%, and all your oil ways are clear.
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Hmm, I am sure but I'll keep kicking, when is enough though? One wonders how many kicks is a filter full?
Maybe I should have opened the stopper valve when I primed the pump, otherwise how does it get that first 'glug' ?
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It takes a good while doing it on the starter before you see oil at the cam so kicking will take forever. Take your cam access caps off and keep the cam lobes lubricated with an oil can. Then just keep kicking.
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If the cam has lube on it. I can't see the point in putting oil on it. It would be hard to see if oil has reached the top end.
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I've left the gallery plug out for now, so I'll get plenty of warning before the oil goes upwards, just seeing some in the gallery would be an improvement.
Triggers 20 percent rebuild rate due to no oil pressure on rebuild worries me. I'm going to drop the pump again at the weekend, I want to double check the feed side is primed ok, I may take the stopper valve out while it's submerged in oil, then replace. I'm going into town soon, a tub of Vaseline may be on the shopping list
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I hate that feeling if the pressure does not come up as expected, leaving you trying to decide if to investigate further or still try to get the light out.
Vaseline is not a bad method, I have always worked on V8 Rover engines on which it's a prescribed method of priming the oil pump after assembly. It's odd on that as the pump is a paired gear type which builds no suction when empty so absolutely requires this method. You even have to be careful during oil changes to make sure the oil filter is not taken off with the sump empty as the oil in the pump head will run back down the pickup tube to the sump and require dismantling the pump to get it going again was a Vaseline repack.
Oil pumps generally aren't total displacement devices and don't really start working well until dynamic sealing with oil when spinning gets them to deliver at the expected volume. One way of priming any type of pump is to fill via the outlet then spin it so the vacuum starts to pull the feed through. I appreciate that you can't get to that side of the pump in this case, the nearest I could get to that was as I wrote previously of trying to fill the oil filter first and reassemble to see if any of that oil would make that sort of arrangement.
Further thoughts are to point a fan heater at the oil tank for half an hour to get the oil less resistant to pumping. Put a piece of tube onto the tank breather with a tire valve in it to pressurise the tank by a couple of psi and force the oil to go through the pump as you turn the motor over.
The design criteria of an oil pump requires that you, within reason, turn it continuously to get the following system to prime from empty (it's that oil within the total system that prevents a run back of oil when you stop any motor) so you may need a team of kickstarters to work in relay to get the pressure up, or spin it on the starter motor.
The killer on these is that the oil restrictors to the head are blocked (covered in other posts on here) and prevent one or both sides of the cam being oiled. That won't show on the oil pressure light anyway as the gallery pressure still builds with them blocked. Don't think you've even got oil near there because your gallery is empty.
Just a further thought, the motor running while shredding the original bearings.......all that scrap will have passed through first the scavenge side of the pump as it was recovered from the sump....... and then again through the pressure side of the pump on its way to the filter BEFORE it was caught in the filter material. Can you see any effects of that inside the pump?
Just remembered that pump was giving you a low / flickering oil light during running before you stripped it if I recall correctly, you need to be certain that's not going to catch you out now.
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There was some marking of the oil pump end plates, but it wasn't bad, and the wear on the rotors was low, I don't think it got to run sick for very long at all.
I did some Googling of priming oil pumps with Vaseline, and got several results from US V8 forums, apparently old Buicks and the like can only be primed this way, though there were still posts from good old boys who thought Vaseline was for sissies, and had never used a torque wrench because pappy said so.
Pump off, gloves on, pump apart and I packed the stuff into the inlet until it came out of the port in the pump, same from the engine side after undoing the spring to the stopper valve. Put it back together and packed it between the rotor and the outer, end covers back on, and slightly turning the pump caused Vaseline to rise from either port. In case I got an air lock in the oil line, I got the pump mostly on but not all the way, I put a bit of oil in the tank, once it started coming out all over the oil pump I pushed it up and tightened the bolts.
Sump plate back on, then I put a pint of oil in, some into the gallery (bike was on the side stand), some into the cam box to drain back down. A few kicks and oil started coming back out of the gallery - result! Put the gallery plug on, lots more kicks. Checked the oil light, well and truly out.
I could hear gurgles from the cam box, and saw a weep of oil around the rocker spindles. There was a trace of Vaseline floating on the oil in the tank, which can only have come via the return, so that side works too.
At the start of this thread, the oil light was staying on up to about 1200 rpm, albeit with hot oil. I can now make it go out with 3 kicks, using cold 20/50. Eventually I tried the starter (coz my leg hurt), it struggles to get going, then spins happily, if slowly. I hate to think how it would cope with the plugs in. Trigger will be along soon to tell me off, I didn't do it for long though.
I'm considering changing the oil to 10/40 - I used 'Classic' 20/50 because it was what I had, bought when I had low pressure. Now I'm worrying I may have too much oil pressure, leading to leaks or hard starting ::) It would be kinder to use a thinner oil I'm sure, particularly while it is as tight as a tight thing. It span over much easier when I had no oil circulation, so I reckon its the cold thick oil being a bugger to pump round, not an over tight engine trying to seize! (that reminds me, a line on Westworld last week that made me laugh, when someone asked if the glass was half full or empty - 'We are engineers, the glass was designed to the wrong specification!')
If I do drop the 20/50 you can be sure wont be letting the oil pump run dry. I haven't seen a ton of oil upstairs but I'm guessing I wont, at least until its been turned over a lot. The fact that there is any sign of oil coming from the spindles can only be good, though.
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So you did not believe me about the Vaseline and had to question my advise :(
20/50 is OK if you are running the engine in, in the summer months. You still need to see loads of oil at the cam ;)
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Hmm, that didn't go too well. :(
I left the battery on trickle charge overnight, just went out to the garage, 12.5 volts, barely turns the engine over at all with the cold thick 20/50 in it, no spark plugs. That can't be right.
I'll try it with 10/40 when I get some, it span over quite happily when it didn't have oil pressure, but I am worried. One extreme to the other $@#~!
The O rings and carb top seals arrived this morning, trigger, thanks! :)
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Mine's still running on Duckhams 20/50, used it since 1976 (not the same oil) though I will have to change over soon as my "stock" of Duckhams has run out.
Cheers
Dennis
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That 12.5 appears too low for a battery that's just been charged.
A healthy one that is new will be about 12.95v with full charge and getting very much below 12.6v with no load would normally indicate that it really doesn't have much left in the way of starting grunt.
You could try jumping it off another vehicle, the battery size (if bigger) is immaterial but it will just turn over for longer before slowing down.
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I agree with K2-K6, your battery needs a big boost. You cant have too much pressure, that is what the pressure relief is for.
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I put it back on charge last night. I just checked, 12.8 v, still struggling to turn the motor over at all. It's not a very old battery, but it is old tech, I managed to stain our stainless sink putting the acid in! I have seen a yellow glass mat one on eBay, I have a similar one on my Harley, expensive but bomb proof.
I can check the connections are tight try jumping from a car battery, but I still worry it's tight, and if it doesn't wiz round with a bigger battery I will try 10/40. Should there be an earth strap somewhere? We have a painted engine bolted in a painted frame when all's said and done.
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Yes, you need a earth from the battery to the frame. The eye of earth lead has the top rear engine bolt through it.
If you are confident that your clearance is spot on and oil is in full circulating , then hook a car battery up.
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I've been using a Varta ytx14 bs which is a AGM battery on my cbx750. It's one of the best batterys I've used on a bike with really good turn over speed and starting. The cbx doesn't have a kickstart and also a slipper clutch, so if I have to bumpstart it then have to push it about 30mph in second gear to get it to go! It just always spins and starts with this battery unlike mixed brand stuff I've had before. Some of them haven't even lasted a year.
I'm reluctant to call things rubbish, but most of the batterys I've had before come very close to it but this one is great and about £44 delivered. Don't know how that compares to a moto bat cost wise.
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I'll root around and see if I've missed an earth strap in the parts box, I'm sure we didn't fit one.
I can't see it in the parts book, give us a clue if you know where it is, but I know it's important on the 911, there's a copper braid strap beftween the gearbox and the chassis, and the starter doesn't behave if it's not there, because of the high resistance path between the starter and the battery negative terminal. As I see it, we have the same situation here, I'm guessing it wasn't as important with the exhaust on, it's steel, and bolted to the motor and to the frame at the same time, both metal to metal. Anyway it should be put right, as I say we currently have an earth path back from the starter through a painted motor bolted to a painted frame. Now I think of it, the triangular plate at the front offside mount was missing some paint where the engine bolted to the frame, so I gave it a good coat of satin black.
If I have to I'll order a 911 one, hopefully someone can suggest a cheaper alternative, as any Porsche part is reassuringly expensive (but the highest quality).
Edit just seen Triggers post, not sure where my earth lead goes at the moment. I'd file the paint off the engine mount (that bloody paint causing trouble again) but it's in now.
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You can do a quick and dirty test by putting a jump lead from battery negative terminal straight to the sump plug to give you earth bypass and see if it improves.
Cars, I always fit two separate earth leads to make sure it's got redundancy from running a rally car, if one gets snagged or compromised it'll still start.
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That's a good idea.
The Harley has two earth straps as well, but it is a fully rubber mounted engine, so it wouldn't work without.
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You can do a quick and dirty test by putting a jump lead from battery negative terminal straight to the sump plug to give you earth bypass and see if it improves.
Cars, I always fit two separate earth leads to make sure it's got redundancy from running a rally car, if one gets snagged or compromised it'll still start.
Why run a earth to the sump plug, when you can earth out the starter motor ;)
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Yes you're right Trigger, I was just thinking of some easily accessible bare metal that you can easily get a big crunchy old jump clip onto without scratching the engine paint.
It's something I use on old landrovers as the quickest way to verify the earth.
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I see the point, but it doesn't make a difference. I tried a jump lead from the negative terminal to the kickstart, but I'd already measured zero resistance between -ve terminal and the engine so it's not that. After an initial struggle it turns quite well, but that first moment is horrible.
I'll try a car battery tomorrow, if it's ok I'll order a solid state modern one, either to rule it out or make it maintenance free, as I recall old technology lead acid batteries often died when they got cold and flat.
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It's a possibility that the previous owner and yourself between you have knackered the starter motor brushes, replacing them is cheaper than a new battery, and provided you clean out/undercut the mica segments in the commutator it should be fine again for many years. ;D ;D
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Worth checking, do I need to take the alternator cover off, I reckon not?
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No, just the chrome cover on top of the engine behind the barrels, no oil to spill ;D
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Its off and apart, what do you think of this on a scale of 0 to banjaxed?
Pretty damned filthy, I don't know if that's my problem totally, but it can't help. I'll sort this before trying a new battery or 10/40.
I'll order new brushes tomorrow, DS has the genuine article in stock.
(https://s5.postimg.org/5p3lyd7vb/IMG_1776.jpg)
(https://s5.postimg.org/50urff95j/IMG_1777.jpg)
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That needs a good clean. Use WD40 and scrape all the grooves on the copper with a tooth pick.
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Orrible with a capital O, best cleaner is Armaclean but not that easy to get
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That's probably the PO turning it over with those tight main bearings as it ground lumps off them ;) does look pretty mucky.
Looking at oil temp range in Honda manual, and it says 20/50 ok down to zero degrees. 10w just extends usable operating range lower to -15c so I can't see it would affect it. It may be at ambient temp now that the two are all but identical in practice.
I know Bitsa always advocated 20/50 for these and I've always used it without any problems partly because of the top temp range is useful if it's running hot. Queing in and out of road race bike meetings always got mine stinking hot.
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If you look in the Honda manuals in My Drop-box Dave there are refurb detail in there. It may be better in the CB350 twins manual than the 750 one .. not sure & I can't check for you at the 'mo. All of the Mutsuba starters have armatures/commutators/brush arrangement which are basically the same, it's the gearing & wattage that differs.
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Right, cancel the gel battery and the thinner oil, the starter refurb was a 100% success! No pics yet but the +ve brush was 1/4 inch long, the service limit is 1/2 inch. I doubt the spring was even working.
Yet again you guys made me spend £12 and saved me £100.
The motor whizzes round, the oil light goes out after a few seconds, and I can now confidently report to Trigger that there is oil upstairs in the cam box that I didn't put there.
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👏👏👏 Well done Dave, I bet there was a huge sigh of relief when it all worked as it should do
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Awesome well done Dave...!
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It's one thing people often overlook, I would guess that 90% of bikes our age have never had anything done to the starter motor bar removal and refit for engine rebuilds, and most are more than 40 years old, and people seem surprised that they fail due to worn brushes! Still, glad you got it sorted, next is to get it running! ;D ;D
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Hairy, see all problems are down to electrics on these old girls ;D
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Hairy, see all problems are down to electrics on these old girls ;D
I know, that's how I learnt so many ways of sorting them, plus an apprenticeship as an auto electrician at Lucas many years ago, I know you find electrics a pain, but it's really just a case of logic and physics! ;D
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Hairy, see all problems are down to electrics on these old girls ;D
I know, that's how I learnt so many ways of sorting them, plus an apprenticeship as an auto electrician at Lucas many years ago, I know you find electrics a pain, but it's really just a case of logic and physics! ;D
I work with logic everyday but, Physics as well ? Right, time for another beer :)
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Hopefully we can close this thread soon if there are no more dramas to come - SHE RUNS!
I finished after dark yesterday, but here she is in one piece again, ticking over outside the garage, HM300s telling the neighbours that she is back.
(https://s5.postimg.org/hnzyebuhj/07_BC7_D07_63_EC_43_FE_BE81_93882_B45097_D.jpg)
Hard to start until I realised that the throttle stop screw was not touching the stop. The throttle cable adjustment is totally up the pictures, there is a spring in the quadrant,and it seems to take a quarter turn to take up the slack in it, despite adjusting for the right amount of free play. I will have to investigate. I think the cables are the wrong way round as well, as there is an adjuster on the 'close' cable, not the 'open' one, though that's how it was before.
I adjusted the clutch as per the owner's handbook and its not at all right, last time I was in this position I found a good article on the net telling me how to do it properly which worked a treat.
No leaks, no sign of the oil light once running, fresh oil at the cambox, no untoward noises I can hear. She went up though the gears on the mainstand ok.
Once I get everything set up right there will be the nervous ride out to the MOT station, last time is when the oil light dramas started.
(https://s5.postimg.org/8rp6ae3vb/2_E6751_AB_915_E_401_C_9_BFC_5_B2_B4_CC28_A53.jpg)
Finally back in the garage, locked up to the Sportster. The tyre protecting the XL1200 and the 911 door from each other is an old Dunlop Racing triangular, with an alarming profie.
As the Harley was in 1000 pieces up to June, and the CB750 came apart shortly after I got her running again, it is the first time in a long while I have had 2 complete bikes, rather than one and a pile of parts. Top tip, always undo the cable lock and unplug the battery tender before setting off on a ride. ;)
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great news !!
bet you had a big smile after you finished !!
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Looks great and thank f#ck that one is finished.
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Well done for getting sorted out. It's a nice feeling when you get it all back together and running.
I don't think anyone would have guessed at the outset of your problems that it would have such an obscure fault built into it by the previous owner.
The throttle cables are correct, the pull cable has no option for tensioning at the carbs. Just fit and secure with the collar nut. Any adjustment of that one is at the twistgrip but you have to leave enough slack to avoid it pulling the carbs when turning the bars full left and right. The second/return cable is the opposite, having no adjustment at the twistgrip. When you fit that one, make sure there's enough slack so that it doesn't conflict with the pull when at full lock.
With the bars turned fully you should get no binding in those cables at all. If you have, it'll make the throttle much heavier to use. It'll also start to cut the internal sheathing inside the two sharp bends that come out of the twistgrip which also raises the friction in operation.
One area that's not ordinarily considered with batterys if they don't kick out enough grunt when starting is both the sprag clutch, which if driven slowly fails to pinch and drive the crank immediately. This will shorten the life of the sprag in extreme cases as it doesn't really wear much when it drives correctly. And the other being the starter itself, if the start power is lower than ideal then the time you are using the starter can easily be doubled or tripled unnecessarily. They will, if all set up and working well, just start easily and often on the first push of the button.
It'll be nice for you to get out and enjoy it soon, it seems like you've properly debugged it now.
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I haven't had time to readjust the clutch yet, but I found the problem with the throttle. The quadrant had been turning on the shaft, it just needed the set screw tightening and the locknut nipping up. I also rerouted a fuel pipe as it was fouling the Tickover adjuster.
The bike then did something it has never done before- it started instantly from cold! That could be a benefit of the ultrasound bath Ed gave the carbs, he has a video of the crud boiling off them. Before it was a sod from cold. It had been yesterday, but the tickover screw wasn't even making contact, a bit of throttle was needed to start up for the first time.
It sees to be running sweetly, it may be a while until I borrow a decent set of vacuum gauges, but the carb top threads haven't been disturbed. Lock to lock doesn't change the revs, which is good. I'm not getting it too hot, but when I put the Harley back together I was advised to let it go through as many heat cycles as I could to bed it in.
I've tightened the valve adjuster caps now, one of the ones I'd left finger tight developed an oil leak, so its definitely getting up there ok.
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That's a lovely looking bike. When you rebuild a bike it doesn't matter how dark, wet or cold it is you MUST start it just to see if it runs :). The feeling of satisfaction when the job is complete is immense and can only be tamed by a couple of beers with your feet up and a smile on your face :), I'm waiting for that moment with project 400 ::)
Well done and hope it sails through the MOT.
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They do once set up properly start really easily, I think the whole bike is easy to run really but they just look a bit complex.
I'm rethinking how to approach vac gauges on this basis; if the demand on wide open throttle are the same for all cylinders and you set the carb slides to be the same mechanically, then why would you adjust them at idle speed to correct idle smoothness? Surely that's the wrong thing to do.
Honda's description for idle adjust is to warm engine, get stable tickover of 1000rpm and then turning one idle screw inwards until you get a 100 rpm drop in revs, then turn the screw out by 1 1/4 turns to set the correct place for that screw. Reset overall idle speed with main tickover adjuster and then complete another cylinder, continue till all are done. I feel this process will give you even and matched demand for all cylinders. It should be running smoothly at this point.
It does give a routine for the vac gauges, but the tolerance is not that tight. I think people pay too much attention to this without first setting their idles correctly for each cylinder, so in effect the throttle slide positions relative to each other are distorted in an attempt to cope with any error present in the idle circuits.
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I've been fettling this afternoon, now starting and running sweetly, and the clutch is adjusted correctly now, but its frustrating that I can't go for a ride yet, due to no MOT and damp salty roads. I did fix the faulty indicator, a wire had popped out of a connector which I tightened up in the headlight. Next chance on dry roads I will go for a sneaky spin, or just go straight for the MOT if they've a slot free.
Motor looking good back in frame, newly shiny cam cover looking good. I think the stainless hoses are a bit blingy but they'll stay like that. In my picky eyes the best improvement is the new shiny stoplight switch spring, the old one was painted silver. New side panel badges, the old ones had worn off chrome, Number 7 and 8 bolts everywhere, and you can see Rich's damper rubbers in place. I know the allen screws on the clutch cover are wrong, before you say, but they fit nicely and I haven't got the Honda ones yet.
(https://s5.postimg.org/d9fkqao0n/PC170012.jpg)
Outside in daylight for the first time, final touch for Sgt Pinback was a new rubber on the end of the clutch lever, which I found in my box of new bits, as that one was split and kept falling off.
(https://s5.postimg.org/5uq8xx253/PC170007.jpg)
Thanks to you guys for all your help, especially Ashimoto for the crank, which hopefully will have a long and happy life in its new home.