how can you tell if the timing chain is worn?

I bought a project bike off a guy who had took it to a dealer to get an estimate to redo the top end because a valve stuck. On the workorder it says that the timing chain was streched. they wanted to do everything on the bike and it was going to cost big bucks. How can I tell if the timing chain is streched or ok?

Timing chains are relatively cheap compared to the damage a stretched on can cause. Tell tale signs of a stretched chain are that your timing marks don't line up at TDC and your cam chain adjuster is at or close to its max extension.

Unfortunately Yamaha don't give specs on timing chain stretch. On my old ninja for example, they specified Xmm for 20 links. The only way you can do it is measure 20 links on a brand new chain and compare the results with the old chain. Going off the cam timing marks doesnt work very well because if the front chain guide is worn it will retard the timing of the camshafts, giving the impression that the chain is stretched. If the tensioner is only about 1/4 of the way out the chain is probably ok. I look at it this way: a new chain is cheaper than one valve. If the chain breaks it'll probably trash all the valves, the piston, barrel and head, and possibly bend the rod too. Just replace the chain, especially if the bike has has top end problems in the past.

ok I will just put a new chain on. The work order also stated that it needed a timing chain tensioner needed to be replaced. I could not figure this out because I did what the book said with a small screwdriver to wind up the spring and the tensioner worked perfectly. Has anyone had a problem with their tensioner, and if so what does it do or not do? :cry:

This sound like you yamaha stealer just trying to make more $$$ :cry: . These ratchet style temsioners are pretty bulletproof. Wind it in and hold pressure on it, and gradually let it out one click at a time. If all seems well I'd reuse it.

it does not seem to click out, it just comes all the way out very quickly and easy.

On my 99 (if i remember correctly) the tensioner does not "ratchet". It is smooth until you screw it all the way in (loosening the chain) and it stays there. Unscrewing it, it just releases all the way once you get it past the catch, unless you slowly release it with the screw driver.

it does not seem to click out, it just comes all the way out very quickly and easy.

Hmm...ok . It's been a while since I have had mine apart so I may be wrong here. I may be thinking of my ZX7 tensioner which was a ratchet style. Sorry if I mislead you. Hopefully someone else will post to clear it up either way.

i just removed mine 2 days ago, it doesnt click, just comes out easy and locks in a very polite manner

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