Multispeed via "pit bike"

Discussion in 'Performance Mods' started by KeepOnKeepnOn, Dec 3, 2007.

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  1. You can get a complete mini motorcycle with a 4 speed transmission for $500 on Ebay. Engine with 4spd tranny and all the rest of the possibly useable parts. The only reason I can think of for this not being adaptable to a bike is the engine being too wide for the cranks. Anybody looked into this further?
    Last edited by a moderator: Dec 3, 2007

  2. Hi,

    I think it was generally found that the engines were heavy and too wide for use on a typical bike....I think also, many have looked into the Lifan 50 engine (sp?)....but concluded it may be too heavy (I think it was 40+ lbs ) and too wide as well....the search for multi speed is definitely a difficult task given the constraints of trying to keep the bike basically a bike...We'll get there sooner or later....Half the fun is trying huh? ;-)
  3. Egor

    Egor Guest

    Also the problem with the Honda clones is, that the law is that you can not have gears and be a MoPed. Our law is, 2 Hp, no gears and has to be able to be pedaled. And not go over 29 MPH. They are allowing a two speed auto Tomos but still under 29. Have fun, Dave
  4. An ideal engine would have to be one with 2hp detuned as a factory setup...and then upgrade on your own from there...
  5. reclaimer

    reclaimer Guest

    I've been considering one of those. Here in Pa we can have a "motor driven cycle"(MDC). The required equipment is nearly identical to a "motorized pedalcycle". A MDC can have up to 5hp. A MDC with less then 50cc and an auto trans can be driven with a class-c drivers liscense.

    So far all the motorcycle/atv engines under 50cc/auto trans I've found for sale dont mention hp.

    that one gives max power numbers(2.0KW/8500R/MIN) but I'm mathmaticlly challenged. Also I'm assuming brake hp and max hp are the same thing, would that be correct?
    Last edited by a moderator: Dec 14, 2007
  6. reclaimer

    reclaimer Guest

    Math may stop me but google slays it.

    Found a calc. which is telling me that engine is just under 2.7 hp. Would a 26inch wheel just kill the trans?
  7. Alaskavan

    Alaskavan Guest

    Looks like another Honda clone. Here's one a little cheaper. It's a Lifan:

    You might nee a Really big back sprocket. My guess is that the engine will kill a stock bike wheel.
  8. reclaimer

    reclaimer Guest

    Been looking at that one as well. I like the look of it much more.

    If we use a jack shaft to correct the gear ratio, would it still work as it should? I'd hate to build it, then get 25ft and hear it shift twice right into 3rd, lol. unless maybe I didnt have to pedal those 25ft.
  9. Egor

    Egor Guest

    A fifty tooth sprocket would work out about right, but it would kill the stock bike wheel. With the 50cc engine my guess it would top out at about 55mph. Too fast for one of the normal bikes we are using. The engine is about 40 lb. and is pretty wide. I saw a stock Honda with a pedal shaft through the swing arm and some stuff to make it pedal. I have a bunch of the engines under the car in the garage, I have thought about putting one in a bike but it would not be easy. A stretch chopper then you could put it behind the pedals. Have fun Dave