Hi Sukhoi_One,

AFAIK, the Jerry Howell (JH) ignition has fixed ignition timing unlike the CH ignition that has automatic advance/retard. It sounds like you have found an advance angle that allows the engine to start easily, but the angle may be too retarded at the top end to produce good power. This could be one reason for the "really weak" performance. Of course, the engine itself is a factor, as mentioned by av8tor1977.

You may want to check the advance angle on the JH ignition. As I recall, the CH ignition, when properly set, changes the advance angle from around 4 degrees when starting, to 28 degrees at top end. If your advance angle is significantly less than 28 degrees, then the top end power could be suffering.

Also, what coil did you use?

Thanks,

Bruce