Good info. Thanks guys.

I have been reading threads in this forum on the 21cc engines. Also the 18cc engines. I am going to go measure the timing on this engine right now. I'll post the numbers in a day or 2.

It has a Walbro carb. The carb is 18/64. How big do you think I can go if I port it a little and drop the cylinder down to .020"?