How Do I Put an Engine on a Roadmaster Bicycle?

A bicycle engine allows you to cycle without pedaling.

Roadmaster bicycles are a favorite among many old-school motorbike enthusiasts. The V-frame configuration lends to adapting a moped or other small gasoline engine as a power plant. One approach is fabricating a motor mount, compiling numerous accessories and installing a garden trimmer or RC engine with an integral gas tank. The everyday enthusiast may find it easier to obtain a kit that includes the engine, exhaust, gas tank, cables and accessories. Organize your bicycle tools and the components from a kit to put an engine on your Roadmaster bicycle.

Things You'll Need

• Bicycle repair stand
• Motorized bicycle kit
• Standard gauge hand tools
• Allen wrenches

Instructions

1. Elevate the Roadmaster bicycle on a repair stand. Ask an assistant to stabilize the bike on wood blocks when a stand is not available. Remove the chain guard, drive chain and the rear wheel from the bike.

2. Position the engine at the inner surface of the front frame tube. Attach the engine temporarily using the mounting brackets and bolts from the kit. Do not tighten the bolts fully at this point.

3. Attach the exhaust pipe and muffler assembly at the rear of the engine. Support the tailpipe in position using a random length of wire looped around the upper frame tube or the seat post and the tailpipe.

4. Rotate the pedal cranks to make sure the cranks clear the exhaust pipe. Reposition the engine, if necessary, so the cranks do not rub against the exhaust. Tighten the engine mounts securely. Attach the tailpipe to the bike using the provided bracket. Remove the random piece of wire used to support the tailpipe.

5. Mount the gas tank on the upper frame tube of the bike using the provided brackets. Attach the carburetor to the intake manifold at the front of the engine. Connect the fuel line between the tank and the fuel nozzle on the carburetor. Tighten the provided clamps at each end of the fuel line.

6. Place the rear wheel of the bike on a workbench with the sprocket facing up. Remove the bolts that hold the sprocket on the wheel hub using an Allen wrench. Position the provided spacer on the hub. Place the new sprocket atop the spacer and align the bolt holes with the hub. Attach the sprocket to the hub using the provided Allen bolts.

7. Mount the rear wheel on the bike and connect the bicycle chain to the motor sprocket and rear sprocket. Attach the provided chain guard or retrofit original chain guard.

8. Install the throttle grip, throttle cable, spark plug and magneto by referring to the instructions provided with the kit. Install the centrifugal clutch on the engine. Attach the provided clutch lever at the handlebars and connect the clutch cable as described in the instructions.

Tips & Warnings

• Review the provided instructions before beginning the installation.

• Some installations may require longer bolts or modifications.

• Use the recommended fuel.

• New engines may require a break-in period.

References

• Clipr.net: 1965 AMF Roadmaster Discoverer
• RC Hobbies: Gas Airplane, Marine & Helicopter Engines