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Message: <blockquote data-quote="Cheek" data-source="post: 2646238" data-attributes="member: 244782">...easy summary about this? im making a mini bike, so this is what it says:We suggest framing the mini bike from 1" tubing. You could certainly use common 3/4-in. pipe if you were so inclined. If you don't have a tube bender, you could join straight lengths with angle iron. But make sure the joints are reinforced since the frame will suffer severe stresses from jolting over rough terrain. Formed channel or a custom solution is needed for the frame base and transmission rack and steel plate for the engine deck. For the axles, we don't recommend threaded axles if you intend use on rocky terrain by scraping past stones. Instead they can be retained with cotter pins and washers. The uprights of the front fork section are also 1-in. furniture tubing or 3/4-in. pipe. The cross members, including the two pivot brackets, are angle iron. These are spaced so that the frame's steering column will seat snugly between them. The lock pin is then dropped through. This pin is 5/8-in.-dia. rod, with an L of 1/4-in. rod welded at the top. This hooks over the upper pivot bracket to keep the pin from dropping through to the ground. It also provides a handle to facilitate withdrawal, once the cotter pin at the opposite end has been removed. Unless you can lap this pin into the frame column for a snug fit, it should ride within bushings pressed into both ends of the column pipe. In the model shown, 5/8-in. I.D. bushings were used. As we said, if you're going to do some heavy duty off road driving, you may be happy down the line if you don't use threaded axles. Or, if you do, use bushings to ensure that no thread is exposed when the wheels are secured. But you can also use special pivoting retainers and forgo the threads. Make your own retainers by welding an L-shape of 1/4-in. rod to one face of a washer large enough to slip onto the axle you've chosen. The tail of the L enters a hole in the plate, holding the axle in place in the notch. (The hub nut shown on the front axle is an alternate treatment.) The defining feature of this design is the enormous rear wheel. The 12-by-16 ATV type has no tube and is kept at only 12 lbs. pressure. At such low pressure, the tire can cups itself around small boulders and logs in the path, smoothing your ride. Also, with the design's 8" ground clearance, you won't get stopped by small obstructions nearly as often. With such a large and low pressure tire, it's virtually impossible to spin out loose soil or mud, or on ice. It floats along on top of sand, making this trail-blazer a practical beach buggy as well. The design calls for a 6-by-6 snow-and-mud tread tire on the front; you keep its tube at 15-20 lbs. pressure. Check your parts supplier for what they offer, and their selection of material for the wheels (aluminum or steel)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 SwitchKeep 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. BrakingEngine 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 shownExtrasRemember 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. The design uses a swing arm that connects to the jack shafts between the engine and the rear wheel. This arm allows you to change the gearing on the step pulley. The spring keeps the arm taught, so your belt doesn't slip off. The transmission rack consists of two channel uprigh</blockquote>

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