Black Ox clutch questions

I am using the Genesis 29" Onyx bicycle platform with the 49cc HS 142f engine and centrifugal clutch and the 4G T belt drive.
On initial take off I get hard vibrations as the revs pick up it smooths out and is fine. I am very concerned about the hard vibrations. I have felt that if I had a slipper type clutch I could rev it higher than release the clutch and not have the problem. I have two questions; would gearing it lower help it get going and allow me to get revs up to a non vibration level. Or is the cent. clutch engage too quickly and not allowing a suitable rpm to be reached. So do you people think a cent clutch modification is the answer or do you think a lower gear (bigger rear sprocket) is the answer. BTW with the wheel off the ground it picks up revs really nice. If you think the clutch mod. is the way to go, what would be the mod?

I have to pedal it to get underway, but probably more as I hit the gas. Pedaling is a bit of a problem for me, the thing is hard to get going due to the 29 inch wheels and the wide pedal, to make it all worse the replacement sprocket is large and makes it hard to pedal. I would really like to motor start. As of now I am using the stock exhaust and intake. I am thinking that it is a matter of too early a clutch engagement