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  1. #1
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    Default Dangerous chain jaming ..

    Hi All,
    I've searched for chain jamming & lock-ups with little success .
    Has anyone solved this HP motor engineering flaw when the chain gets bound up trying to clear the small drive sprocket causing the back wheel to lock up .

    Sick of locking up my back wheel , my chain is tight enough , think it must be poor original design that allows this



    Cheers Bobby .

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    You're talking about jamming up at the front end, aren't you? Under the clutch lever?

    If I've got that right, then I have to suspect that yours has some kind of flaw since what you're describing isn't common. At least I don't think so. I think I'd have heard of it and it hasn't happened to me.

    Is that cover fastened down tightly?
    License??!!...We don't need no stinkin' license!!!

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    Quote Originally Posted by bluegoatwoods View Post
    You're talking about jamming up at the front end, aren't you? Under the clutch lever?

    If I've got that right, then I have to suspect that yours has some kind of flaw since what you're describing isn't common. At least I don't think so. I think I'd have heard of it and it hasn't happened to me.

    Is that cover fastened down tightly?
    Yep thats it , I've got three bikes & its happened to all of them , but only once to the one with a centrifugal clutch .

    I think I know what happens the chain slows downs on top as the bottom tightens up causing the jam kink on the clutch housing .

    Bobby .

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    yes it has been discussed around here in a few places

    would say -- since you have stated chain is tight enough

    something mis matching at speed -- teeth to chain

    better quality chain may help ?? ((slight)) file to gear teeth -- taking off sharp edges if any ??

    good thick grease on chain -- try for a while ??

    MM
    Last edited by Mountainman; 11-16-2009 at 06:17 AM.

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    Quote Originally Posted by Mountainman View Post
    yes it has been discussed around here in a few places

    would say -- since you have stated chain is tight enough

    something mis matching at speed -- teeth to chain

    better quality chain may help ?? ((slight)) file to gear teeth -- taking off sharp edges if any ??

    good thick grease on chain -- try for a while ??

    MM
    Thanks I've done that & ridden around the place with the motor off to double check smooth chain meshing , bikes are going great then for many miles then "WHACK " a lock up that can kill me

    Cheers Bobby.

  6. #6
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    Iv'e noticed with mine that the chain stretches quickly and loosens up.
    Also if you walk the bike a couple of sprocket teeth at a time does your chain go tight loose tight loose?

    Once the chain gets a little too loose it'll jump off.
    Usually happens to me at low speed.
    If you watch the chain when your riding.
    When you first start the thing up and it is 4 strokin alot.
    The bottom of the chain bounces around alot.

    I'm not sure what the best soloution to this is yet.

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    Quote Originally Posted by 210061741 View Post
    Iv'e noticed with mine that the chain stretches quickly and loosens up.
    Also if you walk the bike a couple of sprocket teeth at a time does your chain go tight loose tight loose?

    .
    Yes Sir , that always happens , also did you notice when you lift up your back wheel and increase revs the chain bounces Big Time .

    Gotta think the Chinese just make stuff but don't ever think of fully testing anything ?
    Maybe I just got a bad bunch of motors put together by assemblers who didn't get fed or didn't give a hook at the time ?

    Gees " what does quality control mean in China ? Answer output output

  8. #8
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    What i have found is the 10T sprocket is a little small for the chain.
    It causes alot of excess pin pressure.

    The other thing that isn't realized is even moving the motor .030 of an inch will make the chain loose by allmost a link.

    Dosen't seem to make sense....

    I know this cause i use shims behind the rear motor mount to adjust my chain tension.
    I have found through experience that eve .030 of an inch makes a big diff.

    I'm thinking that i want to design a Motor Mount that makes adjusting the chain tension the turn of a bolt.

    Of course you would have to loosen the 4 bolts first but that can be done alot easier than getting thoose shims in place.

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    Quote Originally Posted by 210061741 View Post
    What i have found is the 10T sprocket is a little small for the chain.
    It causes alot of excess pin pressure.

    The other thing that isn't realized is even moving the motor .030 of an inch will make the chain loose by allmost a link.

    Dosen't seem to make sense....

    I know this cause i use shims behind the rear motor mount to adjust my chain tension.
    I have found through experience that eve .030 of an inch makes a big diff.

    I'm thinking that i want to design a Motor Mount that makes adjusting the chain tension the turn of a bolt.

    Of course you would have to loosen the 4 bolts first but that can be done alot easier than getting thoose shims in place.
    Appreciate your input , I'll check that out , so you think the supplied 10T is part of the flaw in there design ( whoops copy ) also your point regarding motor placement as the problem , that I agree is critical .

    I noticed the torque will always pull a motor to the left even though all bolts are tight , gee that could be it !!

    Regards Bobby.

  10. #10
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    Hi Bobby. Mine wasn't as bad as yours, but every now and then there was a pretty decent clunk from the vicinity of the countershaft sprocket. There are marks where the chain has hit the front edge of the inside of the countershaft cover. I found that the cause was a stiff joining link, staying more or less straight as it passed over the 10-tooth sprocket. It only happened when my chain got a bit loose. I think that a spring tensioner is a necessity on these things. In my opinion, to make things reliable and trustworthy, we need a decent roller on the bottom as a main tensioner, then an additional spring tensioner on the bottom to take out slack as the chain tightens/loosens as it rotates and a simple non-roller UHMW (ultra-high molecular weight) plastic guide on the top to stop the chain jumping around too much during starting/throttle off/downhill with clutch in.
    ... Steve

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