SOHC.co.uk Forums > CB500/550
CB550K - engine rebuild (partial or full)
K2-K6:
"- how to inspect cam chain and tensioner properly, having removed valve cover?"
Initial rough check of camchain;- just try to lift the chain at the highest point on the cam sprocket as it compares the chain pitch with the tooth pitch. Any more than approximately 1mm and it's worn to excess. Meaning that a new one cannot ordinarily be lifted, 1mm and you'd consider planned replacement, 3 to 4mm definitely finished.
Tensioner, again a rough first impression of if it's adjusted, turn the crankshaft backward 1/2 turn and check for slack on the front chain run if you can access it. An old bicycle spoke may allow you to just hook the chain to pull it back toward the rear of engine to assess if there's too much play. Or make a little wire hook to do this.
It really gives just a first impression of anything wrong. The cam chain lasts quite well though but obviously you'd change it if you did the primary one.
Erny:
Thanks all for advices and explanation
What about primary chain? Based on video and your experience, is it possible to say of chain is on its end of life?
K2-K6:
Adding to the above, the chain disguises it's wear really well and is unlikely to fail. They just go on getting more and more loose but with the tooth form and design (the way the chain changes as it bends) keeping it running quite effectively.
The limits for this engine are particularly, that it will end up touching the crankcase casting, and that it will make more noise when idling.
This one is not so urgent that you'd have to stop using it and change immediately, but certainly to plan for work to get the parts and complete when convenient for you.
As Oddjob says, the cush drives need to be considered if you are stripping to change the chain.
Erny:
OK, thanks for your feedback. This is my feeling too - so highly likely I'll open engine to replace primary chain + cush drives
deltarider:
It is with hesitation that I show you the pics of a new and a used primary chain. I found them on the German site. As told before, the chain on mine has now served over 138.000 kms. I am still far from the guy who's CB500 at 220.000 kms still had the original chain. These chains stretch no doubt, especially in the beginning; more than once have I read that somebody became dissappointed when in less than 15.000 kms after replacement the new chain was as audible as the old one had been. As far as eating the crankcase, we'll see; I volunteered to be the guinea pig. Note that the chains shown here, are called new and used. I avoid the word 'worn', because I don't know if that is the case.
(Courtesy Spargeljo)
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