Honda-SOHC
SOHC.co.uk Forums => Project Board => Topic started by: Charlie J on August 10, 2020, 08:44:27 PM
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Just getting started on rebuilding my project Honda Four which I introduced in the new members section. The confusing Subject title is due to the fact that I don't as yet know quite what I've got. The crankcase is stamped CB500 whilst the cylinder block has 544cc stamped on it. I thought from info from David Silver spares that it was a K2 but BryanJ tells me we didn't get a K2 in the UK and it might be a K1.
Anyway, it is what it is and I'll see what I can make of it. First job was to see if I could get the engine running after the bike had been left in a shed for at least 30 years.
So jobs done so far;
Stripped and rebuilt carbs which as you would expect were completely gummed up. New needle, jets, gasket, airscrew etc. The biggest problem was trying to fit the non-shaped o-rings. I had to resort to the use of super glue in the corners to get them to stay in place
New plugs, point and condensers
New oil and filter
Static timing set
Valve clearances adjusted
Timing chain adjusted
Rigged up basic ignition and starter circuit wiring (a lot of the original wiring is missing/damaged
Rigged up temporary fuel supply
Connected to booster start battery charger
Hit my makeshift starter button
The bike fired up immediately ;D ;D I almost danced a jig. What a wonderful feeling, but it didn't last long. The bike dumped half her oil on the floor, used 2 pints of petrol in 10 seconds and filled my shed and the surrounding neighbourhood with exhaust smoke.
Back to the drawing board. Traced the oil leak to the bolt inside one of the side covers on the cylinder head cover and got that sorted. The disappearing petrol was coming out of the overflow of all four carbs. When I rebuilt the carbs, I set the float height to the specified value of 22mm which just didn't work, I ended up with a height of 26mm using the clear tube method. Fired her up again on the button and the bike is running well but with clouds of grey exhaust smoke. Checked the cylinder compression and it's about 135 psi on all 4 cylinders which I hope is good enough. Next job is to change the valve stem oil seals whilst leaving the head on to see if that sorts the smoke problem.
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Sounds like fun 😁😁😁😁
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550 barrels on a 500 bottom end was a popular upgrade back in the day, but it involved machining the crankcase mouths out to suit the larger diameter liners. You'll have a lot of fun with that bike, nice little middleweight that handles nicely. Never, ever stamp on the gear lever to shift down, the forms are easy to damage, probe to bending, and near impossible to get now at reasonable prices. Welcome by the way!
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Remember to do the compression test with throttle wide open ....
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Remember to do the compression test with throttle wide open ....
Thanks SPR. Throttle was wide open.
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Just trying to post an update on my project but don't seem to be able to attach photos. So this is just a test. Apologies in advance.[attachimg=1]
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Great photo 👍👍👍
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Well I managed to attach a photo of the bike so I'll continue with the update. As I said in an earlier post , after getting the engine started amid clouds of exhaust smoke, I thought I'd try an easy fix of changing the valve stem oil seals with the engine in the frame and the cylinder head in-situ. I removed the rocker cover to find that it was in a pretty bad state with bits broken off.
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I'll try and get these areas repaired the best I can. You can also see in the photos that the tappet caps have seen some treatment from a hacksaw in the past in order to sort out where they had been rounded. I had to use 15mm, 16mm and 17mm spanners to remove them!
There is also an irregular shaped hole which I don't think should be there.
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I don't think it does any harm, unless someone can tell me differently? The tachometer drive also looks beyond repair.
I used a Sealey VS1542 Valve Collet Remover/Installer
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to remove the valve springs so I could replace the oil seals without removing the cylinder head. I was a bit apprehensive about using it as I had read some reviews that said the tool was fine for removing the collets but not so good at reinstalling them. However, the tool worked a treat for me. The only slightly tricky part was dealing with the exhaust valves on cylinders 2&3 because of the proximity of the posts for the fuel tank mounting rubbers. But a sharp tap, square on with a 2lb hammer did the trick. I also used the string down the plug hole and rubber band tricks which I read about on this forum. I can't remember who posted them but many thanks anyway.
I reassembled everything and used the damaged rocker cover as it was just to see if the oil seals had done the trick. The bike fired up immediately accompanied by clouds of exhaust smoke. So much for an easy fix! I'll take the head off next and see what that reveals.
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So, next stage in the rebuild was to remove the head and cylinder block to try and identify the cause of the smoking exhaust. I think the photo speaks for itself.[attachimg=1] There is significant pitting to the cylinder sleeves. I’ve checked the cylinder bores and they are standard 58.5mm for the 550 head (which is fitted to the 500 bottom end). It looks to my inexperienced eye that a fairly deep cut will be required to remove the pitting, possibly requiring the 3mm oversize pistons available on eBay from Cruzinimage. A 3mm rebore seems a lot to me, does anyone have any views on this?
I also have a spare 500 cylinder block with standard 56mm liners. The liners have a light coating of rust and two vertical scratches in one of the bores that are just detectable by a finger nail.
This leaves me with a number of options and I can’t decide which is best so would welcome any advice.
3.0mm oversize for the 550 block with new pistons etc
Minimum possible rebore for the 500 block with new pistons etc
2.5mm rebore for the 500 block and reuse the existing pistons with new rings
There may be a problem with using the 500 block because as Hairygit pointed out in a previous reply, the 500 crankcase has been machined to accommodate the larger diameter liners of the 550 block. There is only about a mm or so difference but I don’t know if this will cause a problem, so again, any advice will be greatly appreciated.
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My email is in my profile, send me some pics of the base gasket area on crankcase, the later cases had big enough holes from Honda to take the 550 cylinders.
3mm over is a lot but there are so called 605 kits with liners out there, lots of options.
Mail me and we will discuss it
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So, following some gratefully received advice from BryanJ, I’m going with a 550 cylinder block with a 0.5mm oversize rebore. Not only did Bryan help me out with his expertise, he also offered to do the rebore for me. How good is that!
Whilst waiting for the rebore to be done, I took the sump cover off to have a look at the primary drive chain. As can be seen from the photo, any hopes of good news soon disappeared.
[attachimg=1].
The chain has a huge amount of free play and has been chewing its way through the crankcase.
Just got the cases split after whacking with a rubber mallet for 10 minutes before I discovered the ‘secret’ bolt in the sump area! Next job is to take a look at the crank bearings, but following my discoveries so far, I’m not too optimistic about them being in good shape. Oh well, all part of the fun as they say.
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I’ve also learned how to nail a cup of coffee to the ceiling :)
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That looks quie clean in there so bearings could well be OK. Remember to keep the shells where they came from as you will not be able to identify the size if you mix them up
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Thanks Bryan
Will do.
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Just an update on some limited progress made since my last post.
Rebored cylinder block picked up from Bryan. Great job done and I got the benefit of picking Bryan’s brain for half an hour - priceless. He also took a look at the crank, shells and cam chain tensioner and confirmed they were ok to reuse. Thanks again Bryan.
I bought the bike without a log book. The process of getting a new V5C was fairly straightforward. I filled in DVLA form V62 with my details together with the frame and registration numbers and sent it off with a cheque for £25. I got an acknowledgement from DVLA a couple of days later saying that my application should be processed on 01st October and a V5C issued within a few days. Got the log book through the post on 5th Oct so no complaints there. Next step will be to get it SORN’d.
I’ve cleaned up the casings etc ready for painting with VHT paint but just have to wait until my wife goes out so I can use the parts washer for the final clean. For some reason, she seems to think that just because it’s fitted in the kitchen it should only be used for dishes!
Once the cases were apart I could see the damage that the primary chain had caused by chewing into the casing. [attachimg=1]
Splines on kickstart spindle also stripped so have ordered a used replacement from eBay [attachimg=2]
Have dual purposed my bike lift as an engine stand using a length of rebar and some threaded bar. I was afraid to use my work bench in case the engine got lost amongst all the other stuff.
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The four gearbox bearings look, feel and sound ok to me, so given the high cost of replacements I am considering reusing them or is this false economy? The clock shows that the bike had done 47k miles but I have no way of knowing if this is accurate. Any views/advice on this would be welcome.
Thanks
Charlie
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Thanks Oddjob.
I’ve put it on the ever increasing shopping list. The oil guide is not available via CMSNL or DSS but there are a couple on eBay from Germany - £32 + £16 postage!! I’ll check mine out to see if the damage is in a critical position. If not, I’ll try some super glue.
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Hi all
Just getting around to reassembling my front forks after a refurb and need some help in identifying an item I had zip tied to one of the dampers. I’m guessing it’s got something to do with the front suspension but cannot remember where it came from and can’t find it in the manual or parts list. The forks are off a CB500 K1
Thanks in advance
Charlie
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Never seen one like that before
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Thanks Bryan, if you don't recognise it, then it's probably not important. I'll just throw it in a box of odds and sods and who knows, one day I might remember what it's for!
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I haven’t been very good at posting updates on progress, but after just about replacing everything apart from the frame and engine casings, the bike is more or less finished (see below).
It didn’t take me long to realise that my project bike was not complete enough and was in such poor overall condition that a “correct” restoration was going to cost more than I was prepared to spend. So, I just did my own thing with a vague picture in mind of what I wanted to achieve. I’m quite pleased with how it looks and the engine starts on the button and runs well with no oil leaks. I managed to do everything myself except the rebore (thanks Bryan J) and the seat reupholstery. Also thanks to all on the forum. I spent hours reading and learning from the sohc community.
However, I do need some more advice if anyone can point me in the right direction please. I rode the bike a few hundred yards down the road and all seemed well until I tried the back brake. There was a definite “pulse” through the brake pedal. I didn’t notice any cracking in the brake drum lining and have renewed the wheel bearings. I’ll recheck the drum lining, but is there anything else that I should be looking at that might cause the problem?
Thanks
Charlie
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99.9% that the cast lining is cracked and lifting, sorry for bad news
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That looks really nice - great work. I'm like you in not having funds for full redtorations, and it's nice just to get something back on the road.
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Nice job. My second project is not too dissimilar.
Second the rear brake theory.
Like those clocks. Can I ask from where you got them?
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Great build, it looks brilliant, uyou must be really chuffed? Which exhaust is that, different from the norm and suits it really well, and teh shocks.
Another one on the road, well done.
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That looks great Charlie and looks a real fun bike to ride. Well done for saving her. Enjoy.
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Thanks to all for the kind remarks. It’s certainly a nice feeling to have rescued the bike from turning into a complete rust heap. The sound of the engine firing up on the first press of the button after the rebuild was music to my ears. Just need to get the brake drum sorted now.
For those that asked:-
Clocks were dirt cheap from EBay but look good, work fine and seem to be of decent quality. Here’s a link for where I got the rev counter from. I think I got the speedo from the same place.
https://www.ebay.co.uk/itm/154291886420
Exhaust is Marving Honda CB500 Four Complete Exhaust - RACING Line 4/1 - Chrome from https://www.wemoto.com/
TEC Adjustable Damping Gas Shock Absorbers - Honda CB500 CB550 Four SOHC from
https://www.tecbikeparts.com
Regards
Charlie
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Cheers, Charlie.
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Brilliant, cheers Charlie. Am I right in saying that the 500 pipes will fit the 550 then?
Mine is too far 'passed it' to restore so its going to be a resto mod like yours but love the pipe, I'd forgotten about Marving and to be fair not having done heaps of research yet as haven't needed to, I'm liking the idea of those pipes rather than mine which although standard are a bit jaded to say the least and the PO has had the grinder to them already. Might be an easy win for me.
Cheers
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Mmmmm, Marvin. Pipe of choice for the 500 back in 1975. Bloody loud though, as I recall.
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Nice deep rumble with the removable baffle fitted. Deafening with it out. Think I'll be leaving it in, rather than risk the wrath of the neighbours!
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I had a Piper too (avatar).
I took the baffle out once.
That was enough.
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Am I right in saying that the 500 pipes will fit the 550 then?
I can't guarantee that they will fit a 550 as I have got a 500. They are advertised as fitting both. I'm sure others on here will know if there are any differences. Or you could give Wemoto a call. I found them very helpful.
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As a rule of thumb you can get pipes to interchange from cb500 to cb550 but you'll need to play around with the rear footrest hangar and also be wary of having a stop for the centre stand which can hit the chain if the required stops aren't in the right place on the exhaust brackets / system. In other words be prepared to spend time drilling, cutting, and bending steel or alloy if interchanging exhausts from cb500 to cb550. I have always chosen exhaust systems for these bikes based on what I can get cheap. Currently I have a laser 4 into 1 fitted, not too loud unless you really use the throttle, then it's pretty anti social.
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Way back when i had aMarving on a 500 and withthe baffle out it was so loud nobody would ride behind me, my mate lived 5 miles away and knew when i left for work!
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Bryan, once I get the rear brake drum sorted, I'll do you a ride by after you've been on the night shift to remind you what it was like ;)
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You can re arrange the following words into a well known phrase or saying
Up
Rev
And
Off
Sod
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Haha. :) :) :)