Originally Posted by kjmillig
OK, so I've blasphemed at the thought of installing a gas engine on a bike to use for commuting, but they're claiming extreme MPGs.
is the forum to go to for bicycle gas engine info.
First you want to find out if motorized bicycles are legal in your state.
Ask your dept of motor vehicles "if you put an engine on a bicycle yourself, if you can still ride it on public streets". Don't ask them about "motorized bicycles" or "mopeds", because in many states, those are technically different vehicles. Every now and then there's somebody who buys and puts a motorized bike together, and then they get told by cops or the motor vehicle dept that they can't ride it--because motorized bicycles are prohibited in their state. Many people assume that you can register it as a moped if you want, and OFTEN that is not true.
Cost is $150-$600, plus whatever bike you put it on.
Reliability is basically "you get what you pay for".
Some people have motorized bicycles with engines that they have put 10K-15K+ miles on. Some people make cross-USA trips on them.
I got a Golden Eagle kit, back when midwest/US gas first hit around $3 gal, but it took me a year or so to get it on a good bike for it. I haven't had the chance to ride it more than a couple hours before cold winter weather set in. 175-200 MPG is typical for the 35cc 4-stroke engine I have, and the top speed is 27 MPH.
Some engine kits will do up near 50 mph, but these are larger 2-stroke engines, not the most fuel-economical, or least-polluting.