[Tim Hancock]

Kach, what engine are you talking about? I am quite familar with 2 strokes on ultralights (as well as dirt bikes, snowmobiles etc). On an aircraft, low end power is a non-issue and basically a propellor is matched to load the engine so that maximum power can be reached in flight. IOW, too much prop and engine will never reach max power/rpm, too little prop allows overspeed.

I assume hovercraft (if that is what you are talking about) operate in a similar fashion without any sort of gear changing transmission. If your present engine is not able to reach it's powerband, maybe you might try reducing your propellor load. Or if you are able to reach the high rpms where your engine makes power, THEN you need to increase your prop load AND boost engine power to match.

Depending on what engine you actually have, you may be on your own when experimenting with porting and exhaust pipe changes as "driving a fan" creates a different power tuning than what the snowmobile engine tuners will probably have proven mods developed for.

Raising the compression ratio is the simplest way to achieve more power (custom exhausts and porting work too, but they are kind of an experimental black art), but then you may need to boost the octane to avoid detonation along with messing with your jetting.

Anything is possible, but there may not be any "proven" fixes for your situation.