where can i find a good cheap kit? what can i use for a engine?
A search for "riquimbili" might help you.
Great question, I'm actually really interested in this. So for starters well talk about the engine, you could use the following: Weed wacker, chain saw, basically just a small engine. Then i would suggest using the gears that are already on you bike, the one on the tire you would leave, and the connected to youre pedals you remove and attache to the engine the ( the part that spins) probably by welding it on. You then simply build a stand on the back of youre bike to set the engine on, bolt it down, use the existing chain (the one on the bike) to attach the engine to the wheel. Rewire the clutch to the handle bar, i would suggest using the front brake handle i.e.using the brake handle housing to make the clutch. I know i sounded a little confusing but thats basically it! :) Please i would love to hear how this turns out, any questions feel free to ask and rember like the guy said down there there is plenty of how to vids out there. Good Luck!
Put better tags on your question and you WILL get better related items to the right. e.g motorised bike.
i toataly agree
indestructibles should haev up and down vote things
I don't know how cheaply you wanted to go but these kits are freely available on Ebay for $117/ £117.
For the US ;http://www.ebay.com/itm/60CC-GAS-Motor-Bicycle-2-S...
For the UKhttp://www.ebay.co.uk/itm/Motorised-Bicycle-Engine-kit-80cc-2-stroke-/261263435064
But if you have a old chainsaw or weed wacker engine you can make one for very little expense.
Just type ; chainsaw bike ' into youtube.
It will be illegal on the roads though.