SOHC.co.uk Forums > CB500/550
Engine teardown and inspection
cantarauk:
Hi,
I recently purchased a '72 CB500 which was a bit rough around the edges to say the least with the intention of rebuilding this as a Cafe style racer. I have been taking my time with the stripping down of the bike and am now at the point where I am taking the engine apart which is a new skill in itself.
I have read that camshaft bearing surfaces should be inspected and should be smooth and shiny and if there is excessive wear it or it is scratched it should be replaced. My question here is what warrants excessive wear/scratches as I have seen as bad surfaces on posts where used have said this should be fine.
I have attached some images and would appreciate the professional opinion of the community.
There will be more questions the deeper down the rabbit hole I get.
Glenn
Chris400F:
I don't think I would be able to comment usefully anyway but can't see the images so suspect others won't be able to either.
Can you check they are visible? Are they perhaps hosted somewhere not publicly accessible?
AshimotoK0:
Agree with Oddjob. What does the mating cam cover & camshaft look like ? I think there is a CB magazine article on the 400/4 project bike setup which had been fitted with NOS Villiers engine shells, I think previously carried out by Dixon Racing ( they had fitted a new cam cover and half bearing shell arrangement in the head). This requires precision engineering though.
Your best bet is either a replacement from DK or Jap2wheelz (Frank) in Germany though. Both have a decent reputation and good returns policy. Or perhaps someone on here has a decent spare to sell you.
AshimotoK0:
Further to last post of mine here is the Dixon Racing conversion on the CB bike
Go this below back from Rick Parkington of Classic Bike Magazine regarding the cam bearing shells fitted to the CB400F project bike they are building. Interesting stuff !!
Cheers ... AshD
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Hi Ash, Received your message to David Silver via a rather circuitous route! Afraid I can't offer much more information at present largely because the engine is sitting inverted on its head while I assemble the bottom end! I will by all means take a closer look when it's right way up again. Since the cam cover has no shells fitted, the cam diameter must still be standard and that means that if these are Kawasaki shells, it must be a model whose cam is the same diameter as a 400/4. My issue was that as a machining job it isn't one I'd like to undertake because the head design prevents starting from one end and boring straight through; it would be tricky to get right starting with an already worn head and it wouldn't have to be far out to seize. I'm guessing there's more slack on the fit than there was on the DOHC motors where the cam caps were not avaailable separately and disaster followed mixing them up... The cam cover is away for chrome stripping and polishing just now but I'm looking forward to plastigauging the fit of the cam when it returns. I can see it would be a big help to SOHC owners to find out how this was done (in my bike shop days I used to have a black museum of gruesome SOHC Honda cams!) but I have a feeling finding the shells may only be half the answer, it's a pity it looks like it was done before my mate bought the bike Cheers Rick
Hi Ash,
OK got bit more info now. The bearing shells in the head are not Z1. I popped one out and the number on the back is G (in a square) S8919M. The stamping looked similar to that on Triumph shells, so assuming it was a Glacier bearing I tried Googling the number but no result.Giving up on the Internet I did what I should have done first and checked my 1968 Glacier catalogue. Turns out they are from a Villiers industrial engine. The set number was B 1042 S and the engine is a Villiers Mk12 1.5hp, 120cc. The shells in the head are minus tens; turns out the Villiers standard shaft diameter is 0.874", I measured the cam at 0.864", so using -0.010" shells will make the fit right for the Honda cam. I suspect these bearings will be hard to obtain now but you never know.Speaking to someone yesterday who reckoned that back in the day Dixon Racing used to do cylinder head bushing operations, thy supplied the Yoshi parts so that would make sense.Thanks for the invite to the forum; not sure I'd have much to contribute, I'm afraid this is the first four I've laid a spanner on. Work aside I avoid the computer - too much to do in the shed. I actually started a blog this year (www.rickparkington.co.uk) and am having trouble finding the time even to do that! But feel free to use this info and pics. Hope it proves helpful.
All the best Rick P
http://vintagemotorcyclepistons.co.uk/page/5
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Trigger:
I also can't see any pictures.
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