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  1. #1
    Junior Member
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    mini bike transmission?

    yep im a new guy to all this ''technology'' so forgive me if i screw something up haha,anyways i was on eBay ordering a clutch for my custom baja heat with the 5.5 Honda,and wanted to know if there are any ''transmissions'' for minibikes they have them on motorcycles and scooters, i already know about jack-shafts and torque converter ,but i mean like a manual 4 speed or something? do they exist?-will

  2. #2
    Senior Member Motra's Avatar
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    Mar 2008
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    Welcome newcomer! Aside from an old British motorcycle transmission I've never heard of anything. The Mustang Trail Machine used a 3 speed Burman gear box with a manual clutch and kick starter. There have been some high-low gear boxes but those are stop and shift type boxes.

  3. #3
    Junior Member
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    thanks,do you know where i could get one of those stop and shift type boxes you speak of?

  4. #4
    Senior Member
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    May 2010
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    bc
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    Those are mower trans-axles. Some can be converted to run on the fly, but they are big and would take up much space , plus they are typically used with a belt tensioner system and thats with a vert shaft motor.

  5. #5
    Junior Member
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    yea,now i know what your taking about.I had this crazy idea, about making my own. it would be like a bike gear shifting set up adapted to the back of the mini bike,(multiple gears) shifted from the handle bars, but with only like 3 different gears and much more beefy and strong ,to handle the mini bike chain. i would have to make a derailleur from scratch tho. i don't think it would work but then again it might i have no idea, i guess it would be like a 5 hp mountain bike? what are your thoughts on that,is it complete insanity or possible ? thanks-will

  6. #6
    Senior Member
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    I have been researching the DIY transmission, and a method of making it easily.

    The easiest way I have been able to come up with is, a High/Low 2 speed, with chained gearing (a chain variant of constant mesh) and a dog clutch slider(to shift gears).
    Harley's have and alot of other motorcycles have a similar system(minus the chains).

    Now I suggested chains, as they are easier to "make" then hobbing out new gears. Not everyone has those tools nor experience with that kind of machining.
    There is a fellow out there on the net, who has done this exact thing. He made it for his gokart, and apparently it worked alright.

    So a dog clutch method is about how your going to achieve this easily and for it to have a glimmer of a DIY hope(MY opinion).

    Edit- Oh the derailleur idea wont really work too well as that chain doesnt want to flex much at all sideways.

  7. #7
    TAV

  8. #8
    if i were to try a transmission i would use a peerless 350 or 400. theyre really good . i wouldnt use a 700 series though theyre not as beefy and dont like high rpms. the drive isnt parallel to the output though on them so you would need to position the engine forward to back so the output is facing the back tire and stand the tranny verticle.first pic is the 700 series 5 speed. theyre very common but wouldnt work as well. the second pic is the 350 or 400 style id use but they are harder to find and only 3 speed. people put bearings in them to replace the bushings and they last forever
    Attached Images Attached Images

  9. #9

    Join Date
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    You could always do what these guys did. http://www.oldminibikes.com/forum/mo...-one-ours.html I'm doing one now with a CT70 for the transmission. You get rid of the rod and piston, timing chain ,jug, and head. Then you cap off the crankcase. You have a standard shift and built in centrifugal clutch.

  10. #10
    Senior Member
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    bc
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    I have often seen some people do this, but cant for the life of me see any writeup on this or otherwise show how to do this conversion.
    Any one have a link?

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