New to this, have searched for my questions, found no answers....

[macruadhi]

I have decided to build a motorized bike and I have 4 motors from which to choose, motors from a McCulloch leaf blower, a weed eater brand trimmer, an off brand Ryobi trimmer, and a motor from weed trimmer whose manufacturer I've forgoten. I want to be able to change gears while under engine power, I just haven't given the power transmission much thought yet. The biggest questions I have are, how big of an engine do I need?, how much preparation do I need to do to the engine?,(I've seen the videos and read about folks converting a weed trimmer engine into an airplane engine, they cut and ground away just about everything that didn't look like an engine.), and what about rebuilding the tiny engines used in weed trimmers?

Sorry for all the questions, and thank you all for reading.

 

[GearNut]

I have seen plenty of videos on utube where folks show off their creations.
Anywhere from 25cc to 40cc. You are pretty much on your own concerning the how to do it part. All I can suggest is safety first. Don't injure yourself....... or worse.

 

[machiasmort]

This thread might help http://www.motoredbikes.com/showthread.php?t=4770&highlight=gear+weed

 

[5-7HEAVEN]

Sorry...

I have not seen any kits adapting weedwhackers and trimmers thru the gears. There are at least two systems connecting 35cc-50cc utility engines with 76mm centrifugal clutches to run thru bicycle gears. Most DIY conversions usually use friction drive, the easiest way to motorize a bike.

Check this guy named deacon out:

http://motorbicycling.com/f28/how-booklet-2815.html