Motorcycle Repair: XR100 TIMING MARKS, proper stroke, rocker assembly

Question
 I REPLACED THE VALVES ON A 2000- XR100- WHICH OF THE 3 MARKS ON THE MAGNETO SIDE DO I USE TO TIME THE MOTOR ? AND WHAT DO I LINE THEM UP WITH?

Answer
Ken,

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.

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