hey everybody! im new here and to this whole motorized bicycle thing but id love to get into being that im quite the gear head and this can help me save gas from letting me use my 16 mpg jeep as often lol anyways i have an old hardtail giant mountain bike. i was hoping to put in a 4 stroke motor of some sort in it eventually. but now that i just got another look at it, im second guessing wether or not its possible to fir one in there! what measurements do i need to take and can someone refer me to a site that sells a decent 4 stroke? perferably with some size measurements. thanks in adavance!