checking chain/sprocket wear?

I just picked up an '02 YZ426 & am curious how to check for chain wear.

To check this on my KTM 640 Adventure I simply pull on the chain at the back of the sprocket - if I can pull it off the sprocket to the point I see daylight though the chain - it's worn.

I can do this on the YZ, but the bike wasn't ridden very much at all before I got it & the sprockets look great (no sign of wear on the teeth). I'm not even sure if the stock chain on there is an O-ring chain.

Dang I love this bike!! :cry:

Just need to know how to check for chain wear...

how far out are the adjusters. If they are maxed out or close it is a solid indicator that the chain is worn. or take off the chain and lay it on the ground. then arc it out on the floor. a good chain will not are much but a worn one will.

It's the same deal. Pull the chain rearward at the center of the rear sprocket. If you have room for a 1/16" drill under the chain, the chain and/or sprocket is worn. Which one? Look at the roller pockets and teeth on the sprocket. They should be uniformly half round, with each tooth having a chisel shaped point that's the same on the front and rear edges. If it looks like that, it's just a chain.

If the sprocket teeth are "pulled" forward so that they look like ratchet teeth, the sprocket was worn out by a stretched chain. Replace them both.

If the teeth are still pointing straight outward, but the half round for the roller looks more like a half oval, the sprocket is worn, but the chain is probably still near the right length. In this case, replace the sprocket and check the fit of the chain on the new one. If it passes the pull test, the chain's OK.

Always check the front cog too.


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