Pocket bike CVT trans. On 4 stroke ? Good or bad ...

Discussion in 'Hubs, Gearboxes, Sprockets and Chains' started by Jcs1989, Aug 16, 2016.

  1. Jcs1989

    Jcs1989 New Member

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    So I'm sure I'm not the first to ask. But I've been looking around. And seeing talk about using a pocket bikes CVT transmission on the 4 stroke engines. Sounds like a pretty good idea from what I've read it helps give a good acceleration along with good top end. Anyone know more on this ? . . Anyway I'm sure the hoot gearbox I'm using probably isn't gona hold up too much longer. I've got about 150 miles on it. And it's starting to make a whining sound . . Plus I've read some pretty downsided opinions of them . .
     
  2. LR Jerry

    LR Jerry Active Member

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    Depending on what size engine you'll be using, the terrain and carrying weight you may need some other additional form of a ratio reduction system. Especially if you're using a small engine
     
  3. Jcs1989

    Jcs1989 New Member

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    I'm using the Huasheng 4 stroke. And I figured this would replace the original gearing system that comes with the kit. Known as the hoot gearbox. I've got over 100 miles on it. An still seems to be holding up. But the chain is starting to stretch an I'm a little worried it going to give before to much more riding. I'm about 145 lbs the bike is about 65-75 lbs . And I run mostly flat terrain. I chose the idea because I figured the cvt trans from a pocket bike would give me the variability I need to climb hills better and accelerate better but not diminish my top end. Or even giving a better top end. . I jus wondered if they would bolt on to a huasheng and function properly...
     
  4. Tony01

    Tony01 Well-Known Member

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    A cvt of any type will diminish your top end. They are highly inefficient and are generally used with engines with more power to make use of them. I think for a 50cc the best setup would be a sturmey S3X hub used as a jackshaft, with an overall gearing of around 15:1. With a top rpm of 8500 and 26" tires this will give you a top gear speed of 43mph. See the posts of bowljoman for some IGH setups.. He got it down to a science.
     
  5. maniac57

    maniac57 Old, Fat, and still faster than you

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    I'd tend to agree with Tony01...
    Unless you're running a 212cc A CVT is just too much loss.
    A typical 79cc would be quite slow with a cvt and would need very low gearing to pull itself around
    However, a 212 will easily be in the 50mph range with a typical CVT setup
     
  6. Jcs1989

    Jcs1989 New Member

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    Keep in mind this is designed for the smaller engines. Like the 49cc engines. I see other members commenting about them. Saying they work well. At 78$ for the cvt I'd be willing to give it a shot. Considering my hoot gear box is about to give I'm sure. The little chain in it has stretch ed out. An it's probably nearing 200 miles. Double what most people say they are good for.
     
  7. LR Jerry

    LR Jerry Active Member

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    I say go for it. I was told an autoshift system would never work yet I've been riding my motorized autoshift bike for 7 years now.
     
  8. Jcs1989

    Jcs1989 New Member

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    What's this auto shift ? I'm basically jus looking for something that's gonna have better take off from the get go. I have to pedal to 15mph to get the engine to pull hard enough to take off. But it does top out at a nice 36.1 mph. An cruises from 26-30 mph now that the clutch is worn in. But I'm still having trouble climbing steeper hills. It gets almost halfway up an then slowly bogs down to 15mph an I have to pedal assist the rest the way up. It's not to bad tho. I don't mind pedaling a little. As I've pedalled 60 miles one way on a crappy mountain bike once lol. . . Jus wanting to find a way to tackle those hills darn it.
     
  9. LR Jerry

    LR Jerry Active Member

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    I personally use a Landrider derailleur to do my autoshifting my bike has a Staton Inc 18.75:1 reduction gear box and Staton shiftkit.

    Brian Kilduff has just come out with a new autoshifter. He has three different kinds of autoshifters now.

    https://youtu.be/iUIvDdNVQN8

    He can make this new shifter work with freehubs or IGH's
     
    #9 LR Jerry, Aug 23, 2016
    Last edited: Aug 23, 2016
  10. Jcs1989

    Jcs1989 New Member

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    Dude that is sweet ! So it basically works like an auto trans in a car . That's pretty cool ... I do have a 29er sitting around collecting dust. If it had a better frame it'd be motorized. I may have to try the auto shift on it. Once I learn more on how they function. I may can possibly design one of my own.
     
  11. LR Jerry

    LR Jerry Active Member

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    I built mine as a form of a legal loop hole. Many places laws state automatic transmission. Some even go as far as to say the operator can't shift engine driven gears. If you're big and live in steep hill country you need gears for under 50cc.
     

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