SOHC.co.uk Forums > CB500/550
Top End Build Help!
Oddjob:
Shame you’re in Kent Neil, miles away from me near Manchester. I’d have been happy to pop over and fix the problem for you.
One thing I think I should mention, just in case. I remember you having a problem getting the cam chain onto the sprocket. Unless it’s a new chain you can normally do that with fingers only. A new chain tends to need a little help with some leverage. The reason you had a problem is almost certainly because you didn’t get the tensioner blade to retract enough. That puts pressure on the chain and causes you to suffer because it’s under tension already. The other mistake is people try and fit the tensioner after they have lowered the barrels, then you find getting the adjuster bolt through its hole in the barrels whilst also making sure the bottom part is engaged in its retainer slot in the lower crankcase means one of 2 things happen. You bend the tensioner at its lower end or you miss the retaining slot altogether. You don’t spot that unless you know it’s likely to happen and you’re so relieved it’s finally fitted you don’t think to check. That now means the tensioner is rubbing against the primary chain, lots of little pieces of metal slowly being ground off and going into the oil. Not good.
The foolproof way of avoiding both problems is to stop lowering the barrels around 2” above the gasket. Then fit the tensioner, it will now fit straight very easily. Get the blade and push it back hard after releasing the locknut. As soon as it bottoms tighten the locknut. Easy once you know how. Don’t fit the upper bolt until you’ve fitted the sprocket and then release the locknut. Leave it loose and then try and align the top bolt hole. Sometimes it refuses to line up and you need the tensioner loose in order to get it to line up. If you need to get the tensioner blade to fully retract whilst the heads still on, just release the locknut, slacken off the top bolt a little and use a big flat bladed screwdriver and lever it back, then lock it off.
If you’re worried you’ve missed the retainer slot in the lower crankcase you can check by removing the sump and looking up, you can see if it’s missed or not.
Neilw:
So the jury is in, and it's not good news.
All of the valves are bent. I had to straighten them slightly to get them out by applying horizontal pressure at the top of each one.
What are my options now? I don't know the condition of the valve guides, and I don't know how to check.
Feeling gutted tbh.
Bryanj:
Easiest is a used head complete with valves, also cheapest way to get a full set of valves, as to guidessee if any have broken tops
Neilw:
--- Quote from: Bryanj on August 04, 2026, 12:41:13 PM ---Easiest is a used head complete with valves, also cheapest way to get a full set of valves, as to guidessee if any have broken tops
--- End quote ---
Theres this one on Ebay? https://www.ebay.co.uk/itm/257610142722?_skw=cb500+550+cyclinder+head&itmmeta=01KZ68WP5D8CHZCAXHY5M53BY9&hash=item3bfac2d402:g:hOsAAeSw~klqTKGy&itmprp=enc%3AAQALAAABAGfYFPkwiKCW4ZNSs2u11xBs7J5UtyIjAPmqD9%2BgdFSqt%2B2zA%2FruhpU1522RFoFTen5%2FPPInSnLhTEC980dIuEnLY%2BT%2FFvnvWT9mvdF0R1N1e1HmmZ%2BPXIIBdQ3d9EztOWqStND3oe3sbvXSLIrqwjwx2mz8a507G6tI3ScRvuuT1j307Mcc7%2FYCpZs95kgfrHoUSzRlZXubCNRdhvRfaUGmV6Q5wEs%2F8tBMp4zE6go0jTNztdaqI63v2nv116DtL%2B%2BlIL39ASigIZLmqFQXXgln0Bsu0kjiCzZLJEAlimC8AGvsKFwW%2BaEuVLLRVVoLVFrBSb3ASCHEm5zt2eCUI6I%3D%7Ctkp%3ABk9SR-Tj8sj5Zw
Oddjob:
Dirty and will need dismantling to clean it all out but journals look ok. Your decision but I’d check your existing head first for guide damage. Someone on here is bound to have some spare valves, I had hundreds of them at one time.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version