I know what to do with the sleeve and have already done so making a huge difference, but what do I do to the crank without changing the timing? Do I just make the standard groove bigger or something?

Without the proper tools modifying engines is a hit or miss deal.

Better have a spare one cause the odds are against you. I have ported different engines and each one responds ina different way.

First thing you got to mention is how your engine performs.

Does it flood on the top end or bottom end?

Is the engine running too hot or seems to be always in the 200 range with minimal tuning. You have to be very careful because you can end up with a flooded engine or an engine that will never idle no matter the needle settings. Do you have restrictors to control air flow, have you thought about opening the carb.

I had a few Force .25 that I opened the carbs and the power increase was sick, but then it started to get lean and thats when I had to dremmel the crank and sleeve. Also there is a small trick done to the button head by making one to three small channels 180 degrees opposite from the exhaust port side. I think it came out in the XRCars magazine. I used to do it on most of my engines and have noticed improvements on the top end.

This is a very sensitive topic, I just fiddle with engines when they are almost dying to see if I can get something out of them. Lately I dont touch them anymore because you will end up messing it up than having any gains.