hello mate thats a cool project, defo keep us posted. ive got a kids quad bike i got given with a fuked engine so i got a kawasaki ar125 engine with 6 gears and fitted it and built loads of components for it and its an animal!!!! your squshed onto this tiny quad bike (your feet onlt just fit in the gap between front and rear wheels) and if you can get going with out flipping wen you nail 2nd you can lean forward and power wheelie!!!
i say get a little 125 super bike style bike like the kawasaki ar125 so you can use the wiring and sprokets, front brake as rear, and you dont even need a battery to run them!!sweet project you make me want to post pics of the quad(project suicide) up on here