Motorcycle Repair: 1999 honda xr100 timing, camshaft lobes, honda xr100

Question
ive been trying to figure out what position to set the "o" on the cam gear in order to time it in. the top rocker no longer has a timing mark do to wear. i have the piston TDC, but it still isnt timed in right.

Answer
Matthew, If you haven't bent the valves by having out of time, here is the easy procedure.

Piston at TDC (T mark)

Camshaft lobes DOWNWARDS in an upside down V   (/-\). That should allow the sprocket to install on the camshaft with the O punch mark straight up to the top of the cylinder head opening. You can also adjust the valve lash at this position... .002"

Bill Silver