I'm converting a Honda GX31, the carb has been changed for a normal butterfly type carb so I put a nipple into the inlet manifold and another on the carb as the impulse ports do not line up. This works very well and now gives me the option of trying several size Walbro's although the one I have right now appears to be ok as the induction port on te head is only 10mm in dia so a massive carb would only flood the engine unless I did a lot of porting. I assume the fourstrokes need a smaller port as they only bang every other rotation. for now I'm sticking with the mag ignition but was wondering if I were to go the CDI route whether the timing would be 28 degrees as per 2 stroke or if it's different on a 4?
I have read these engines will throw say a 16" X 8" prop at around 6,000, I wonder if they have enough torque to throw a larger dia and less pitch for a slow flying 1st WW type thing such as a 1/4 scale Pup or maybe even a 1/4 scale DVII?