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scott6058

crf100f timing chain adjustment

5 posts in this topic

I'm not an expert, but I'll take a shot at it. If I say anything wrong, the experts will correct me.

On the side of the cylinder head opposite the spark plug there's a screw held in place by a plate that is held by a bolt. When the slot of the screw is pointing up and down, the adjuster is in the middle of it's adjustment. Usually, if you turn it to the left, it tightens the timing chain and if it turns to the right, it loosens it.

With the engine running, loosen the bolt with a 10mm socket. Turn the screw to the left (ccw) until the valve noise decreases. When it's too loose, the chain goes slack as the rockers come off the cam. You are trying to eliminate this slapping of the chain and cam.

Tighten the bolt holding the plate. When it's adjusted right, you should have a high pitched whine when the engine is under load.

Anybody have anything to add?

- Brad

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IMO, If its whining, it's a little on the tight side. Could cause premature guide ware or failure. I recommend backing it off a little.

The Clymer service manual states to make the adjustment on the head first. Personally, I adjust the at the cylinder fist. The head adjuster is a to big of a increase, for a routine maintenance. Use it when the cylinder adjustment is maxed out.

Some more info

http://www.thumpertalk.com/forum/showthread.php?t=708766&highlight=

All the best:thumbsup:

G

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