Originally Posted by BarelyAWake
You could try it... but I assure you to "just throw a cog onto the driveshaft of a 4.5hp briggs or honda" is far
more complicated than it seems, not least of which being that the briggs doesn't fit on yer average bicycle, yer perhaps overlooking the wonders of a clutch, and that if you don't wish to spend a lil for a kit setup - yer gonna get into some serious DIY stuff just as (if not more) complicated than figuring out the drivetrain
Sounds like from your lack of interest in "complications" yer prolly best off w/a 4 stroke rack rack mount but as a heads up - yer gonna pay a lil more for that simplicity.
Ya might wanna dig around in here a bit, what yer talking about is
not only possible but a lot of our members have come up with some interesting solutions: DIY Home Built Motorized Bicycle (non kit) - Bicycle Motor at Motorized Bicycle Forum
Just wanted to throw this in, should you get a kit have fun with it, but I really like the challenge of fitting a 3.5hp 4 stroke 80's era briggs engine on 26 inch frame of a JC Penny’s Foremost Bicycle from the 60's era. I will eventually get pics and am nearing getting it done. I just want to get the covers on the sprockets, chain, pulley, belt, and jack shaft for safety reasons. I also have a paint job to do as the frame was removed of all paint for the time I was welding a mount and adding brakes mounts. The coaster brake is gone since I will have no pedals, just foot pegs as it is for off roading.
Bicycle J. C. Pennys Foremost
This link has a pic, but my Foremost frame has the center arcing strengthen tube starting lower down toward the fork neck and up higher back at the seat post. This enable me to fit the engine, but on a 15 degree tilt back. I had to eval quite a few things to think the tilt mods would allow it to be done, but I think I got it done. Carb float bowl, splash oil lube, were the tilt challenges.