I have a VoneSII and am having problems with the engine running rough at high revs. I have rebuilt the motor to ensure that there are no air leaks. It has a new glow plug.

When running at higher revs the motor surges and there is a lot of small air bubbles in the fuel line.

Does any one have any suggestions for what is wrong ??

Many thanks to all.

Nic.

Blow in the "fuelline" that is connected to the exhaust for pressure and hold up the "tank cap?" and check so it isn`t clogged. If it is ok, then set you carb to the original settings, this should be explained in the manual. Hope it helps.