Jump to content
Sign in to follow this  

Cam chain tensioner

Recommended Posts

Been working on my 1990 XR 100 for what seems like forever now. During my top end rebuild i have installed a BBR 120 kit.

I finally to the point where i am installing the new cam sprocket and chain i purchased.

The manual i have says to push down on shaft that rises up from the bottom half of the tensioner (tensioner rod) and then to tighten the tensioner adjustment screw and locknut. This is supposed to give me the slack that I need. I have the BBR cam in place but I am having issues with getting enough slack on the chain to where it will fit over the sprocket once it is installed onto the cam.

If I do not push down the tensioner all the way and allow the thicker part of the tensioner to rise over the tensioner eccentric then I have enough slack to get the job done. I am pretty sure that the fat part of the tensioner is not supposed to be above the eccentric but next to it so that when turning the eccentric it pushes the tensioner against the chain, this is the case correct ?

Here is a picture to illustrate -


As you can see the top of the tensioner is above the eccentric in this photo and there is plenty of slack.

Any thoughts ?

Thanks !:thumbsup:

Share this post

Link to post
Share on other sites

Put the chain on the sprocket *before* you bolt it up to the cam. Line up the timing mark "T" on the flywheel with the mark on the left case, there is a "O" mark on the cam sprocket that should face straight up also at top dead center, with the cam lobes facing down. Make sure it is timed correctly or you will bend valves!!

Regarding the cam tensioner adjuster, the punch mark facing up on the upper adjuster is the loosest setting for the adjuster. After getting the chain on, loosen the adjuster screw on the back of the cylinder to take up the slack, retighten, and lock the lock nut.

Now turn the upper cam tensioner adjuster 1/4 turn clockwise so the punch mark is at 3 o' clock. This is the standard position. I hope this makes sense, I just put the same big bore in my 02 xr100 last week, the procedure should be the same. If you have any other questions just ask.

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

Reply with:

Sign in to follow this