Motorcycle Repair: SL100 head on SL125, piston crown, combustion chamber

Question
Bill- thanks for the help earlier about replacing the timing sprocket on the SL125 crank (i did it per your answer and it works).
My question here is: will the SL100 head work on the SL125?
The chamber volume seems the same, the valves seem the same size including stem... is there any reason why not to use?
Thanks!  Bob

Answer
Bob, the combustion chamber is beveled on the edges to accept the larger bore of the 125 piston and lower the compression slightly, I suppose. The rest of the hardware is pretty much the same. If you want to bump the compression, use an XL125 piston instead that has a nice little raised crown section.

When I raced my CB125 I wound up using the 100 head over a Yoshimura piston that was almost the same as the XL piston crown. 225 psi compression!

Glad the cam timing worked out for you, previously.

Bill Silver