Minibikes are fun ways to entertain young teenagers as well as adults. Building a minibike in your spare time in the garage is not as hard as it may seem. If you want to assemble a minibike, you will need a frame jig, two wheels, a motor and a steering and braking system.
Purchase six pieces of 5-foot long and 3-inch thick steel or metal pipe at a home improvement store. Use a tape measure and measure 4½ feet in length across the pipe. With a hacksaw, cut five 4½ feet long sections that you will use for the bottom rails, steering yoke and center brace. Bottom rails and the center brace are what hold the frame in place. The steering yoke is a protruding horizontal tube that forms the base of the minibike's handlebars.
Lay out three 4½-foot long pipes on the ground. Assemble the three pieces by attaching two aluminum engine-mounting plates to the center of the bottom rails, and then weld them into place. Measure correctly the required space for the engine, which will allow for enough seating room and other attachments.
Place the steering rod in the center of the steering tube piece. Apply solder to the yoke section and weld the bottom rails together. Fit the rotating steering tube to the yoke, add a brace plate and weld both to the minibike's frame. In most cases, steering tubes are a quarter-inch thick and are much wider than the minibike's frame pipe.
Place the engine within the center bars of the minibike. Use clamp holders to secure the engine to the frame. Many online hobby or motorcycle stores sell two-stroke, air-cooled engines that generate 45 miles per hour.
Weld the engine to the minibike’s frame. Attach the main support cross bar to the top and bottom frame rails. The frame rails make up the backbone of the minibike. The engine will rest underneath the seat.
Add two one-foot metal plates on both sides of the engine. Weld each one to the frame. The medal plates will protect and hold in place the engine underneath the rider’s seat.
Steering System and Wheels
Cut the minibike's center bar and fit it to the steering yoke area according to the measurements you've previously taken. Manufacturers sell these metal bars in various shapes. Weld the metal bars in a diagonal line from the center bar. Make sure that you weld a center support brace connecting as well as securing the two pipes together.
Position the center support brace onto both rear side tubes, slightly behind the engine block, and make sure you weld it into place. Weld the cross section braces to the double tube, which is below the center bar, next to the engine.
Attach one wheel to the front axle and the other wheel to the rear axle of the minibike.
Align the handle grips with the brake plate and position the bottom rails vertically, with the mounting clamps at the bottom.
Slide the drums onto the spindles and adjust the wheel bearings. Install the cotter pin and dust cover. Cover the bearings for the drum/hub assemblies with wheel bearing grease and install a grease seal.
Attach one cable from each brake to the minibike frame using a ring connector and self-tapping screw. Add a second wire to the brake grip, which runs to the brake connector.