Motorcycle Repair: 77 honda xl 125, honda xl 125, rotor case

Question
I was wondering about the timing on my xl. i wante to know how to adjust the timing and how to know my bike is at top dead center. i also would like to know the point gap. Please answer if you can.

Answer
Well I used to have a TL125 and I think the motor is the same.  There is a little cover at the left side top of the crank case.  Remove that cover and you will be able to see the F and the T on the crankshaft.  F is for fire, when the points are supposed to open/close, and T for top-dead centre.
Check point gap, setting it to .014" on the highest part of the point cam, then move the point plate around until the points just OPEN at the F mark alignment on the rotor/case markers. The biggest problem with these bikes is that the camshafts wear in the cylinder head, so the point cam wobbles around wider than the initial settings when the engine is running. If you can move the end of the cam around more than about .006" you will have a really hard time keeping the timing correct. You will need to have a machine shop either do a needle bearing modification or buy a new head. Note all of these sizes are in INCHES.

Good luck,  Jan