Homebrew scooter, ~120mpg

[HeadlessNorseman]

25-30cc weedwacker engines have enough power to run a 20 inch bicycle with a fatass teenager(old me haha) at about 18-20 mph. That was prob more a limit to gearing as the engine was def redlining. Im pretty sure 25 or 30 was possible. Im going to start constructing something very soon, at first just a motor powered bike but later i will build aero bodywork

http://ecomodder.com/forum/showthrea...a-14759-3.html

[Grant-53]

I ran a 23cc Bumble Bike 2 cycle engine years ago on a Huffy 3spd bike with a Yamaha Virago windscreen. Cruised at 25 mph with a 1 in dia. knurled shaft turning against the 26 in tire. Too bad it is banned now in NYS. Still have all the parts and papers. If my daughter goes to college in PA I may mount it on her bike. I'd guess 150 to 200 mpg possible.

[elhigh]

Originally Posted by Grant-53

I ran a 23cc Bumble Bike 2 cycle engine years ago on a Huffy 3spd bike with a Yamaha Virago windscreen. Cruised at 25 mph with a 1 in dia. knurled shaft turning against the 26 in tire. Too bad it is banned now in NYS. Still have all the parts and papers. If my daughter goes to college in PA I may mount it on her bike. I'd guess 150 to 200 mpg possible.

Similar hardware is readily available and legal - dunno about NY. Check out Golden Eagle Bike Engines. Belt drive, but I've seen other companies do the friction drive too. The smallest engine will get you down the road at 26mph, which is supposed to be a scosh above the legal limit.

[peasandcarrots]

are there any diesel engines with power outputs that small? I'd be interested in making one of these I can run on homemade biodiesel, for rides that are longer than I can bicycle (>20 mi)

[alvaro84]

I've seen a video (in Hungarian) about a home-built diesel MZ bike. It had a small general purpose diesel engine (sold as garden equipment), which had a performace of ~3hp. Its FE in that setup was <80mpg though, so it's far from the perfect solution. But there may be better engines for this purpose, there are really working (and much larger!) diesel MCs that consume less fuel.

[Frank Lee]

That Suffolk looks like a blatant copy of an old B&S but fitted with a funky carb.

[HeadlessNorseman]

I intend to use a honda gx31 4 stroke. its meant for powering tillers and whatnot. A note is that also most small engines are far from perfectly tuned from the factory. Especially 2 strokes, they run very rich even for 2 stroke standards, its a safety system. so some sort of o2 sensor or exhaust gas analyzer would really be helpful for getting the best FE. Getting 100mpg out of a friction drive 2 stroke untuned is a worst case scenario

[Grant-53]

I have been looking for small diesel engines over the last couple years. The smallest single cylinder engines are around 200cc. The Hatz engine is very popular for economy contest vehicles in Europe and are available in the US. A single cylinder diesel will vibrate a good bit. My pick for a motorcycle engine would be a 3 cyl 700cc Kubota putting out 17 hp.