ive always wanted a scooter but there so dang expensive, then i saw the bike motor kits on ebay for only 114 bucks. i saw ones that range from 40cc to 80cc i still dont really know how to choose from those two, and many other motors which are are under 160 bucks. i was thinking of getting one of them but i dont know which one to choose. Which one should i get for a mountain bike, and which one is easy to install and what should i look for, please just steer me in the right direction?