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Messages - royhall

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1
Project Board / Re: CB 500 resurrection
« on: July 22, 2022, 01:27:17 PM »
Hi Gary. Your picture didn't appear. Well on Tapatalk anyway.

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2
Project Board / Re: Honda CB750K5 Restoration by Royhall
« on: July 17, 2022, 09:06:59 AM »
A long awaited large box has arrived today from Colin at Predator Motorsports. This was ordered last November (2021) with a £500 deposit and has just arrived (July). It contains one replica CB750K5 exhaust system. I was just beginning to get a bit concerned about it so today is a good day. You will notice that it's in a CMS box, that's due to Colin getting them made in Japan then supplying the big retailers such as Silvers and CMS. So it could just as easily been in a Silvers box. The delay was due entirely to shipping costs after the pandemic with the price of containers going through the roof. To be fair to Colin, he honoured the price given when ordering even though costs had increased so it came in cheaper than Silvers or CMS, but not by much.

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I have started preparing for the engine install into the frame. I cant get a bike lift into the limited space in the garage, so as I normally do, the bike will be built up on the same adapted beer crate that I have used for all my previous builds. As every frame is different the crate needs changing to suit. On my 350F build I had to add a step to the top so the frame would sit straight, this time it needs a cut out to clear the side stand bracket. Three pieces of roof tile batten and a piece of plywood do the trick.

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A bit of old carpet tacked to the top prevents the powder coating on the frame from being scratched.

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Just as a precaution, I usually cover the frame in masking tape to prevent any dings whilst the engine is going in. The frame usually gets a gentle knock or two as the engine is a really close fit in the frame.

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When I built the Black Bomber I laid the engine down on it's side on the workbench and lowered the frame over the engine and bolted it in. Then stood it upright on the bench and lifted it down onto the waiting beer crate myself. With the 750 there is no way I am going to attempt this myself as the engine is just too heavy for one (unless your an ape with hands like shovels). So I will wait until a mate calls round to help on Tuesday night.

3
Project Board / Re: Honda CB750K5 Restoration by Royhall
« on: July 16, 2022, 05:49:56 PM »
How are you going to do the fly wheel torque up with the top end on ? This should be done by putting a bar through the con rod small ends to lock the engine  ;)
That would be with my large strap wrench around the rotor Trig. That's the way I do it when I change starter clutch rollers. Works okay. Just out of interest, how do you retighten the rotor after a starter clutch change. Surely you don't take the top end off?

The engine has gone in okay with item 3 pre fitted.

4
Project Board / Re: Honda CB750K5 Restoration by Royhall
« on: July 16, 2022, 09:31:54 AM »
The above mistake required me to strip the cams and head back off and re-do the valves. I took the chance to lap the valves again to ensure everything was still okay and no damage had happened. Trigger also suggested that I fit thicker o-rings to the oil feeds as the specified rings were too thin with an aftermarket gasket. On checking, that was correct. The standard ring is an 11*2.5mm item that was the same thickness as the gasket so would only just seal. I replaced those with 10*3mm to get a bit more compression. He also suggested removing the cam tower studs and sealing the threads with threadlock to prevent oil weeping through the threads. Really good advice that I would never have thought of.

So thanks Trigger. The full list of things Trigger says to check is on the thread mentioned earlier.  Mystery problem on 750 cams (sohc.co.uk)

I realise that the head gasket could have been reused but I decided to replace it anyway. I got a full NE gasket set from M&P for £52 so that was the cost of the mistake. The head went on second time around without problems. I use a length of coat hanger wire to keep the cam-chain from dropping down into the cases.

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The six rubber pucks should be fitted to cover the bolts beneath. I usually use some Threebond under the pucks to ensure a good seal. After cleaning and fitting the oil control valves with new o-rings then fitting the locating dowels I fitted the cam towers (don't forget to fit new o-rings to the blacking side of the towers). Carefully threading the cam chain sprocket over the cam, the camshaft was fitted from left to right, then after liberal use of the oil can and some Graphogen placed into the towers. The caps were fitted in their original places and everything torqued down.

With the crank set to 1:4 on the T mark the cam is rotated until the left hand ends scribed line is level on the tower with the cut out uppermost. The cam chain is then moved around the sprocket until the bolt holes line up the tightened into place.

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This time round the rockers slid in correctly and were all bolted down, again ensuring that they went back into their original positions. The tappet clearances were set whilst the rocker box was off as it's really easy to do at this point. The last on the list is to set the crank at 5 degrees from TDC and release the cam chain tensioner. After it springs forwards re-tighten the bolt and locking nut. Not forgetting to fit the speedo drive gear and new seal first, the rocker box was fitted in place and fastened down with all new screws as the engine came with a varied collection of mongrel fasteners.

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After suffering back problems last time I did a 750 engine, this time around I am going to leave off anything that can be fitted with the engine in the frame to reduce the weight. This includes the entire alternator and rotor assembly, starter motor and ring gear, all the gearchange assembly, all the clutch and baskets, and the points assembly. See I am learning. The engine is now ready to go into the frame. So children that will be tomorrows story, sleep tight.

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5
Project Board / Re: Honda CB750K5 Restoration by Royhall
« on: July 16, 2022, 08:56:22 AM »
At this point anyone paying attention will recall my big problem. It is covered here on this thread   Mystery problem on 750 cams (sohc.co.uk)   After going over what happened to cause this problem (other than operator error) I realised the issue. When I remove the valves on stripdown I keep all the valves in a clearly marked piece of cardboard. At a point along the way I removed all the valves from the card and placed then in in the correct order on the bench for lapping in. Afterwards I put them back into the card but got them the wrong way round (not sure why I didn't just leave them in the card and lap them in one at a time). Then on building the head I just picked them out of the card and fitted them not noticing the problem, then the rest was history. Motto of the tale is double check everything. It is so easy to get excited about the progress and rush ahead resulting in mistakes. Lesson learned.

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And even stranger, I had actually taken a picture of the mistake and still failed to notice it.

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6
Project Board / Re: Honda CB750K5 Restoration by Royhall
« on: July 16, 2022, 08:40:45 AM »
A few days later the Threebond had arrived. I spread a very thin coating over every mating surface between the two halves, even when it looks like the area is inside the engine (oil may run down a bolt thread). After fitting the locating dowels and mating the two halves, the ten bolts holding the crank area were carefully torqued down in the correct sequence. I don't know if it's correct procedure or it's just me, but I usually do the sequence at 50% torque then again at 75% then finally to 100%.

At this point I check that everything turns as expected, then the rest of the case bolts inserted and torqued down. I check again at this point that everything moves as should. Whilst the engine is on it's back I checked the primary chain tensioner was in spec. Although it's a new Honda piece you never know if it's correct, fortunately it measured to be at the very start of it's tolerance so that was good.

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Now at this point I went on to fitting the oil pump that I refurbished earlier, unfortunately I got carried away and forgot to take pictures. When the pump was in I laid the engine on it's side with the oil hose connections at the top to prime the pump. It is not possible to just fill the pump as the anti wet-sump valve prevents the air being expelled so the oil can't get in. At this point I remove the valve and fill the port with my oil can until it starts to drip from the pump then refit the valve. I blank the hose connection ports with rubber bungs to prevent the oil spilling back out when the engine is laid on that side for putting into the frame. I then fit the sump plate and the engine stand and turn the engine the right way up. You can just see the rubber bungs in the picture.

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Up next was to fit the new plus 0.5mm Cruzinimage pistons. They come in the kit complete with gudgeon pins, clips, and piston rings. Compared with some Cruzinimage items they are very good quality. Before fitting the rings to the pistons each one is placed into it's respective bore and the gap checked with feeler gauges. All were okay. I usually stuff the crankcase openings around the conrods with rags to prevent a dropped pin locator clip dropping into the cases. The pistons are fitted with the little arrows pointing to the front of the engine. I move the rings around to try and get the ring gaps distributed evenly around the pistons.

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The next part can be one of the trickiest, fitting the barrels. I am using new camchain guides and tensioner as again the old ones were rock hard. I am still amazed that the cush drive rubbers were in such good condition when all the other rubber parts were rock hard.

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To assist in turning the engine I temporarily fitted the alternator rotor. After liberally coating everything in engine oil, I lifted the two centre pistons to TDC and placed wooden blocks under them. I don't bother using piston ring compressors, although I have some, as they are more faff than required. After fitting the tensioner parts not forgetting to thread the cam-chain through first, I lower the barrels gently onto the two pistons and, using fingers, gently massage the rings into the barrels. Once the two centre pistons are in I remove the wooden blocks and allow the pistons to fall gently whilst holding the barrels until they rest on the outer pistons. Again I gently massage the rings into place and then  push the barrels down onto the base gasket remembering to pull the tensioner forwards out of the way.

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7
CB350/400 / Re: 400 - “elasticity” in headnuts
« on: July 10, 2022, 01:02:01 PM »
Just been out on the 350F (not used it for ages) and noticed when I got back an oil weep from the head gasket that wasn't there before. Also it's blowing fumes out of the breather tube. It is slightly overfilled with oil, could that be causing the fumes. The oil weep is probably time for a head re-torque I guess, I will also take some oil out of it at the same time. Runs really well though.

8
CB350/400 / Re: 400 - “elasticity” in headnuts
« on: July 07, 2022, 11:25:22 AM »
So, couple months (and just a few kilometers, really) later. I'm back at square one.
Again, Cilinder 2 is smokey. I started riding, nice and easy. No smoke. Once everything was nice and up to temp I gave the ol'girl the beans and cilinder 2 (I have a non-balanced 4-4 exhaust, so easy to diagnose) started smoking again. Looks like head gasket again.

I'm going to retorque the head again, first without changing the gasket. Remember last time I found 'loose' head nuts.
Could there be anything wrong with my Studs, or Head?
Is there any harm in using an extra ring under the head nuts, just to make sure the nuts are not bottoming out on the studs (because of the aforementioned elasticity)?

I can't immediately remember but someone on forum had one of these head with crack in casting allowing oil to leak into exhaust port to smoke on #3 I think ?

It was long convoluted chase through all the other possibilities, but ended definitely with this outcome.
That was me on the 350F. It was a real head scratcher problem. I ended up rebuilding the top half three times. In desperation I took the head to an NDT place who gave it to a chap called Eddie Current. He was good, he found a crack next to a valve guide that was invisible cold but opened up when hot. I replaced the head with a really good low mileage one off eBay and problem solved. It's never smoked since.

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9
Misc / Open / Re: Vapour blasting
« on: July 06, 2022, 07:03:55 AM »
My 750 engine was done by Higgspeed (the 2 stroke exhaust people) and it cost £125 all in. They had it ready for me in 3 days. It came back full of blast media though, took me ages to make sure it was all gone. That said, no matter how sure you are about your cleaning you can never 100% guarantee you got every single bead. Just got to hope that if you miss a bead or two they get trapped in the filter. That's the sixth bike engine I have had vapour blasted and so far no problems on that front.

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10
Project Board / Re: Honda CB750K5 Restoration by Royhall
« on: July 03, 2022, 09:00:55 AM »
As usual I didn't make it to the garage that afternoon as once again life intervened. But it did get done.

I was very careful to make sure everything was stored correctly so there would be no mistakes putting it back together. The usual piece of cardboard makes a good holder to ensure that the valves go back in the same place they were born into. Likewise plastic zip bags and a marker pen work very well for the other parts. I have bags in a range of sizes from tiny to huge, cheap off Amazon. Later I will demonstrate how easily this plan comes apart with a 63 year old head in charge of proceedings.

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I went right through the gearbox checking bearings and looking for damage and all appears good. The bearings in particular felt like new so that was a bonus. I decided to replace the bearing in the lower case as it requires knocking out and they are only cheap. Unfortunately I ordered the bearing for the opposite outrigger housing so had to reorder the next time I was getting parts. So since I had the parts, the secondary shaft had all new bearings. On checking the cush drive rubbers in the chainwheel they were still soft and pliable so they too were good to go. Again that was good news as they can be awkward to do. It was surprising they were good as all the other rubber components were rock hard. Everything checked in the lower case then reassembly was straight forwards.

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The upper case assembly also went well. I have replaced all the main and conrod shells, and when working out it turned out that every shell was a green. Being sceptical the even Honda could be so accurate I broke out the micrometers, and sure enough all green. With the shells and housing carefully cleaned they were fitted and given a coat of Graphogen.

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The rest of the top half was then dropped into place (that sounds like I threw it in) without problems. Remembering to check at this point that the timing seal and half ring bearing locators were all in place.  I have used all new primary and cam chains and also replaced the primary chain tensioner. The wheels on the old tensioner were as hard as steel.

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Next up will be mating the two halves. It's job stop at the minute as my tube of Threebond has gone chewy. Onto good old eBay and order some more. The courier likes bringing my parts as he is a classic fan with a Kawasaki Z1000 in the garage. He says he hopes I'm in when he comes so he can see the progress. What a nice friendly hobby, bloody expensive though. Next time.



11
CB750 / Re: Carbs - F1 or F2?
« on: July 01, 2022, 10:06:09 AM »
The F1/K carbs and F2 carbs are completely different, even the fitment is different. There is a way somewhere on the internet where you can swap F2 for K carbs but have never seen anything about the reverse. Put simply they don't fit.

12
CB750 / Re: Mystery problem on 750 cams
« on: July 01, 2022, 08:31:09 AM »
I considered it Julie but decided to stay on the side of caution and just replace the seals and gaskets. Already caused enough mayhem for this rebuild. Plus Trig was correct about the oil feed o-rings, the 11*2.5mm standard rings are not thick enough so am fitting 10*3mm.

13
CB750 / Re: Mystery problem on 750 cams
« on: July 01, 2022, 07:55:25 AM »
After reading the above replies it makes it easier for me to enter the confession box. I refer to my earlier post in mitigation.

Me:  Forgive me Father for I have sinned.
Priest:  Which of Gods laws have you transgressed my son.
Me:  It is the holy law of SOHC father.
Priest:  Go on.
Me:  I had a senior moment and put the intake valves in the exhaust, and exhaust valves in the intake.
Priest:  (Large sigh) According to Gods law "Thou Art a f***ing Dick Head"
Me: But,but,but.
Priest:  Your penance is to spend the day stripping back to barrels and cleaning all up, then pay a forfeit of £51.35p to M&P for a holy top end gasket set.
Me:  Thank you Father I am humbled.

14
CB750 / Re: Mystery problem on 750 cams
« on: June 30, 2022, 06:36:08 AM »
Thanks for the info Trig, I'm sure that will be a big help to a lot of people and not just me.

I did check the o-rings were proud of the gasket , but they were only just. As I'm going backwards now I will probably go a size thicker as the o-rings are taking full pump pressure there due to the flow restrictors in the head. That's easy with o-rings but what can be done about the 8 drain tube seals, are there longer ones available? The threads on the cam tower studs I have never considered so I will do that as well. I always use Threebond under the pucks, so that will be a nice clean up job. The tightening down I usually do at 50%, then 75%, then 100% and leave for a day then go round again to check.

As for the problem with the valves, thinking it through there is only one logical explanation. I think I know what has happened but will prove it this afternoon when I take the head back off. This is going to be another hard to live down senior moment. I have been doing ridiculous things for around the last two years and at 63 that's worrying, I'm defo heading for a Dementia ward at some point. Just in the last seven days:

1. Picked up my 5 year old grandson from school. He gave me his school bag for safe keeping while he played on the park. Two hours later a mad rush back to the park, fortunately his bag was still where I left it.
2. Did a landlords gas safety check at a house, everything was okay. Got a phone call an hour later to say no hot water. 12 mile round trip to turn the gas back on (I had to go in case I had forgotten to put the test nipple back on, fortunately I had).
3. Mrs H said "I have put sausages in the oven, turn them over in ten minutes I'm going for a shower". Completely forgot. Sausages black on one side ,uncooked on the other. Yummy.

I could go on but I think you get the picture. I will report back later when the engine is stripped back with the worrying verdict on both the engine and my present mental state. Got to go, nurse is calling it's time for my bath.

15
CB750 / Re: Mystery problem on 750 cams
« on: June 29, 2022, 06:32:34 PM »
The photo was taken as I was stripping it down again, the cams had probably been turned. Something drastic has happened here (probably me again) so going to reverse a bit and see what's happened. It will be obvious when I find it. All part of the fun eh, at least I haven't broken anything.

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