Site upgrade in progress... Core site functions are working, but some non-critical features/functions will be temporarily unavailable while we work to restore them over the next couple of weeks.

Please post any bugs you encounter, but before you do, check to see if it's already listed.

Thanks for your patience while we work to improve the community.

Sign in to follow this  
Followers 0

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

Share this post

Link to post
Share on other sites

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


All the best:thumbsup:


Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  
Followers 0