Hi Rad

Its Keith Lawes from RCV Engines here hoping to help out!!

Will the engine not even run flat out with the plug de-energised?

1/ Could you give me an RPM figure with the engine flat out. If you haven't run the engine in please put at least 10 minutes on it before doing this at lower throttle, then stop it to let it cool, then start it and put it flat out.

2/ Could you also check the valve timing. To do this remove the exhaust and carb, then put the engine to top dead centre between inlet and exhaust. You do this by aligning the key on the prop driver vertically downwards (if port is not visible at all you are at TDC between comp and power strokes so turn the crank 360 degrees). At TDC you should have equal amounts (a couple of mm) of port visible in the exhaust and inlet ports (this is the inlet/exhaust valve overlap, same as on a conventional 4 stroke). If theres significantly more port in one than the other then the engine will need to be retimed. This is straightforward but we'll worry about it if its the problem (which I think is unlikely)

Thanks

Keith