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Old 05-29-2008, 05:58 PM
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Ok, based on the stuff he gave me, here's my mini tutorial thing:


Engine: I would suggest using a harbor freight 6.5 because they're good quality and come really cheap. You don't really need anything more than about 6.5hp, but It's up to you

Drive system: This is where it gets tricky. You need to know what kind of riding you'll be doing to figure out what type of clutch to use.
If you're doing lots of hilly or off road riding, you're probably going to want a tourque converter. these make it a lot easier on the engine for rough riding.
If you're going to ride mostly flat areas or on road a lot, you can use a centrifugal clutch. These don't do as well as torque converters for high demand applications, and they burn up quickly when put under lots of strain. The good thing about these is that they are cheap (~$30) compared to torque converters (~$150+).

Chain: For a minibike or mini chopper, you probably won't need any more strength than #35 chain, so 35 will be fine.

Gear ratios: Here is another thing that depends on how and where you ride. If you have a TC (torque converter) you can probably get away with low ratios like 3:1 without a problem, but I wouldnt go much lower than that (i.e. 20 tooth on jackshaft 60 tooth on wheel). However if you have a centrifugal clutch, don't go lower than about 4.2:1. Remember a higher gear ratio with a centrifugal clutch means longer clutch life.


Controls: you can buy a twist grip throttle with the cable attatched at lots of stores online. You can find how to hook it to the harbor freight engine here: Clicky (Thanks to Ironman for showing how to do this)


Brakes:I would recommend using a brake handle instead of a foot lever, however, this is up to you. There are a few different kinds of brakes:

Scrub brakes: This system uses a paddle to push against the rear tire activated by a foot lever, and wears down the tire pretty fast. This is my least favorite kind of brake, and I really reccomend not getting these. My rating: 3/10

Band brakes: These use a band with brake pads on the inside to sqeeze on a drum attatched to the wheel. These dont do very good in wet conditions, but they're decent.
My rating: 5/10

Drum brakes: These are basically the opposite of band brakes, because the pads are on the inside of the drum and push out on it. These do good in wet conditions because they are self contained, and offer good stopping power. My rating: 8/10

Disc brakes: These rely on a caliper with brake pads to squeeze on a disc. These offer the best stopping power. There are two types of these, hydraulic, and mechanical. Hydraulics have more power, but are expensive. mechanicals will do fine.



Wheels: I use 4 bolt hole pattern wheels, but that's just me. It doesn't matter which ones you use.

Axles: For a minibike, I would put the rear wheel on bearings instead of the whole axle. It is unnescessary for a mini bike to have pillow block bearings and stuff, and the wheel-bearing setup is much easier.



Frame: If you want to weld a frame, you can't go wrong with a mig welder, however these are more expensive than flux welders. I use round tubing (1" .125 wall or something like that)
But you can use square tubing if you want, it's easier to work with. If you can't or don't want to weld though, you can find many cheap frames on craiglist or ebay.

Hope this helped

-Jon
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