Low-Cost Way To Motorize A Bike

Low-Cost Way To Motorize A Bike AG WORLD 33-4-23 Ryan Flynn, Plainview, Minn., has found a way to get around high gas prices. He motorized his pedal bike by mounting a 2 hp Briggs & Stratton engine on it. "It saves on fuel and is cheap to maintain," says Flynn. The engine, mounted between the bike's wheels, has a large pulley attached to it that belt-drives a jackshaft located where the pedals used to be. A moveable idler pulley, controlled by the bike's left brake handle, serves as the clutch. The jackshaft chain-drives the rear wheel. The bike's chain and derailleur still function. "I use the bike's right shifter to shift gears, while the bike's left shifter serves as the throttle," says Flynn. "The pulley isn't coupled directly to the jackshaft, but instead drives an old rake tooth spring that drives the jackshaft. This setup keeps the pulses of the engine off the bike chain." Flynn says he's surprised by the motorized bike's durability. "It worked well right from the start except that I had to install a guide on the front sprocket to keep the chain on. I've taken it to town a few times and in high gear it goes about 25 mph, which is pretty fast on a bike." Ryan recently made a "second generation" motorized bike by mounting a 6 1/2-hp pressure washer engine on a mountain bike. A torque converter purchased from Northern Hydraulics serves as the drive and clutch. He cut the bike apart and attached the engine and torque converter to a homemade frame. The engine is coupled to the torque converter system first, and then to a jackshaft that drives the rear wheel. "I geared the bike so it has a top speed of about 50 mph," says Flynn. "I'm well-pleased with how it turned out," says Flynn. "My goal was to build a comfortable, light and reliable vehicle that would be cheap to maintain, and I think I reached that goal. I can buy bike parts at most hardware stores, and they're much cheaper than parts for cars and motorcycles. For example, a set of brakes costs about $2 and a new tire about $15. "The bike is light enough that I can lift it into my pickup by myself. I couldn't do that with a motorcycle or even a moped. "Riding it feels like riding a dirt bike. It has plenty of power and I think it could go 50 mph or more if I modified the throttle linkage or changed the gearing." He installed motorcycle handlebars and made a seat that mounts on rubber to reduce vibration. He also added a motorcycle rear fender and kickstand. Contact: FARM SHOW Followup, Ryan Flynn, 30272 550th St., Plainview, Minn. 55964 (ph 507 951-4615; 6jffarm@msn.com).

To read the rest of this story, download this issue below or click here to register with your account number.