Motorized Bike, 150mpg?

[dtpmike]

Nice bike.

I have built 2 motorized bikes... one was a happy time kit 80cc...

one was a 196cc push trailer.... what a beast! It pushed my bike to a top speed of 50mph!

I never measured mpg, but they were very light on gas.

[swede]

FINALLY someone has posted about this. I too have made a motorized bicycle with a 2 stroke "80cc" kit that fits right in the frame like a motorcycle. If anyone here likes scooters for fuel efficiency, but feels a little choked about the price of them, these are an excellent option. At a cost as low as 100 dollars approx. you can get an el cheapo kit that will get high FE and low cost, often better FE than one of the 50cc/50km/h scooters that cost 10 times the price.

[skyl4rk]

Originally Posted by Ryland

have you checked your local laws for motor bicycles?

I am quite certain that my motored bicycle is illegal. It could be made legal by getting a moped sticker, getting insurance and building it to moped standards with lights and turn signals. Not sure if I could get insurance for it though.

[euromodder]

Originally Posted by swede

FINALLY someone has posted about this. I too have made a motorized bicycle with a 2 stroke "80cc" kit that fits right in the frame like a motorcycle. If anyone here likes scooters for fuel efficiency, but feels a little choked about the price of them, these are an excellent option.

Though they may use very little gas, two strokes do so in the most polluting way you could imagine.

What keeps amazing me is that 2-stroke engines can still be bought and used in both the US and EU.

[skyl4rk]

I'm not sure if I posted this before, but a few years ago, I took an electric bicycle and built a series hybrid range extender for it. It worked but was quite loud. This is a different bike than the one posted above.

Series Hybrid with Hubmotor - MotoredBikes.com: Motorized Bicycle Forum

The range extender was not really practical, however I learned how to put one together, and I think I know how to do it right, if I ever were to do it again.

I would use a HuaSheng 50cc four stroke with a governor, and connect it to a high voltage (60 to 100V) permanent magnet motor rated at 15 to 20 amps. It could be controlled so that it only starts on acceleration (large voltage drop) or on low battery conditions. I would hope that this combination would provide enough power to run the bike even with a low voltage battery, in other words, with all power coming from the generator.

I had an arduino programmed and ready to control the motor, but found that the range extender needed to be run at full throttle most of the time, so abandoned the arduino controller. It was essentially a voltage detector with a voltage divider to bring the battery voltage down under 5V so the arduino could read it directly, and a large relay to turn power on and off to the electric motor/generator. There was also a gas motor kill switch in there too. The electric motor/generator would start the gas motor when it was connected to the battery, they were directly coupled at the driveshafts.

The downside is that this system is fairly heavy, especially together with the lead acid batteries. I don't know enough about the LiPo charging regimen to know if this hybrid system would work with lighter batteries. My guess is that this system would provide performance of 30 mph. It is not easy to find the right electric motor/generator. I'm not even sure one is available, although an outrunner type might be rewired to create one.

After this experiment I decided that a well made gas motor system is simplest and easiest to build and gives great results if you focus on design for efficiency. At my level of engineering capability (low) a gas motor is a better choice. But I was able to build a working series hybrid bicycle on a very low budget and could build a much better one with about $3,000.

[Frank Lee]

My electric bike (Songi) has pedals but they are not for serious use (bad pedalling ergos and stupid low ratio). Perhaps they were stuck on there to clear regulations. If it was more pedal-friendly I would assist the electric on most all start/accel/hill/low battery conditions, thus negating the need for gasser help. I already try to pedal during those conditions but it can only happen when it's going sloooooow. There isn't much room for fitting a larger drive sprocket and/or smaller driven.

I would like to transfer the electric hub motor, batt pack, and controller to my full-suspension mountain bike so I would gain the above plus the rear suspension, but I can't bring myself to dismantle a fully functional brand-new $1500 machine.

[Grant-53]

Federal EPA spec. does not currently regulate engines under 50cc. That lets the chain saw engine kits in. State regs usually set limits on speed for 20 mph or 30 mph. Lights, mirrors, and a horn are a good idea in any event. A fairing or motorcycle windshield will help FE and top speed.