The Guts of the Bike
Engines, Brakes, etc.
Most commonly people use tiller engines for the power plant on these little machines. They should be horizontal mount. You'll need a centrifugal clutch if the motor you find isn't already equipped with one.
The scooter we've shown uses a four-cycle engine. You'll want an engine-to-wheel ratio of 25-30 to 1. This will depend on your clutch size, are they come in a variety of tooth sizes. We'll be publishing a gear ratio chart to help with this selection.
Cut Off Switch
Keep in mind that this rig is really a two-wheel tractor. If you start it up with the throttle advanced, it'll take off instantly—with grim determination, and a mind of its own.
So it's a good idea to have an emergency switch within easy reach—perhaps a hand-held, spring-loaded cut off switch which will stop the engine the moment you release your grip.
You could part the condenser wire and insert a pushbutton switch, mounting it on the handlebar so you can keep your finger on the button while you steer. If the button is released, it breaks the ignition circuit.
Or, you might use a hand-throttle with a sufficiently powerful return spring to starve the carburetor when released.
Engine compression supplies adequate braking, but it's a good idea to equip the rear wheel with a brake drum so you can install the pedal brake shown
Remember also that it's no trick to make the shafts on the idler pulleys long enough to use them as power take-offs for a water pump or generator. So if anybody shouts "Get a horse!" at you when you chug past them on the trail, you can grin smugly. What pack animal can double as a pumping station or camp-site power house? And this mount is cheap to feed. With the 2-1/2-hp engine shown, a gallon of gas should scoot you through the wilds for nearly six hours.