Motorcycle Repair: 84 Honda xr100, honda xr100, proper stroke

Question
rstr625@juno.com   I have a 84 honda and it bent both the vavles,i put new ones in it and it bent them also there are marks on the top of the piston wherethey hit together. i have checked the bearings on the crank and the piston,the vavles are seated good,how do you set the timing good on this bike it is a xr100. thank you

Answer
Jim,

The valve/cam timing is checked by removing the valve cover, bringing the piston up to TDC and aligning the "o" on the cam sprocket with the notch on the top rocker assembly. You might have to rotate the flywheel 180 degrees to be at the proper stroke. (Verify my instructions via the service manual.)

Since your XR is equipped with a CDI there shouldn't be an ignition timing problem if it was reassembled correctly. Since the base plate isn't adjustable, your timing should be fine. You can use a timing light connected to an outside power source and check that the mark on the flywheel rotor is aligned with the notch/arrow on the case.

A service manual will be of enormous help setting everything correctly.

Respectfully,
Mark Shively