eyrey1 wrote:i found that after id posted this
so did you run yours with the 28 flywheel of change to the 21 ?
ive still got the complete 21 se engine

Yeah I changed the flywheel. It's actually really easy to change (using the correct tools and techniques!) so is a must do really. It will run poorly without the change, and could cause damage. The alternative is to change the timing, which is discussed in these forums too.

Is the engine the only MC28 part? Still using the 21 airbox, carbs etc? Any known modifications to the engine itself?

It's also worth checking to make sure the powervalves are clean, adjusted correctly and operate smoothly.