I have a 39cc Petrol 4 stroke Chinese push rod type motor in a D7 and wondered why the power is low compared to purpose built rc 4 stroke engines.
After looking at the cam shaft it only has one lobe and I concluded that this is a compromise and it should really have a lobe for each valve.
Has anyone modified the cam shaft to gain more power or made a new cam shaft with 2 lobes.

If you're a member of Jim's R/C Boat Dock,there's a guy on there that used to modify Honda 4 strokes. His screen name is his real name,Bob Decortin. If you're not a member just register and wait to be approved.