Bucking bar to camshaft problem.

Discussion in 'Motorized Bicycle General Discussion' started by Santa_cruz_loc, Apr 24, 2010.

  1. Santa_cruz_loc

    Santa_cruz_loc New Member

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    I recently had a problem with my first build (and still my favorite). My camshaft is shaving down my bucking bar(s). Has this happened to anyone else? Should the bar be spinning at all? Can I lube it somehow? :-||
     
  2. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    whatchootalkinboutwillis?
     
  3. Nougat

    Nougat New Member

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    I'm going to guess 4-stroke, if it has a camshaft?
     
  4. Santa_cruz_loc

    Santa_cruz_loc New Member

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    I'm still new at this so my lingo may not be correct. My clutch keeps going out on me. My clutch lever (thought it was a camshaft) is filing down the small bar that pushes the clutch in. This small bar fits loosely in front of a small bearing but when the clutch is in, it will spin and file down shrinking its size and rendering my clutch useless. It's a standard China made 2 stroke engine. Would lubing this bar and bearing be a bad thing? I'm thinking that if I could lube it, When I engage the clutch it wont spin against the cam and therefore won't shave it down. Will this work? If so what lube would you recommend?
    Thanks guys for taking the time to answer this.
     
    #4 Santa_cruz_loc, Apr 25, 2010
    Last edited: Apr 25, 2010
  5. azbill

    azbill Active Member

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    a dab of grease in the hole will make it easier
    then slide the pin back in :)
     
  6. NunyaBidness

    NunyaBidness Active Member

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    I have a similar problem with my clutch. The ball bearing grinds a divot in the end of the little pin and I have to adjust my cable a little tighter. Eventually it will grind the pin too much and I have to either turn the pin around or cut another from a piece of steel rod that I got just for this purpose. Grease does not work to fix the problem and I have been unable to find a fix for this problem yet either.
     
    #6 NunyaBidness, Apr 25, 2010
    Last edited: Apr 25, 2010
  7. crobo

    crobo New Member

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    wouldnt tempering (heating and quenching repeatedly) the bucking bar help this?
     
  8. corgi1

    corgi1 New Member

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    would a piece of drill rod work the cam end would need to be polished and lubed so as not to wear the cam and the ball end flat ,,,wait a min.,,,there is no play in the clutch arm the rod is in constant tention and turning against the cam on the arm while going down the streetand wearing down ,(or the return spring is missing?)when the clutch is squeezed and the bike is setting still the rod doesnt turn,no wear on the rod
     
  9. crobo

    crobo New Member

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    i have heard of people using the shank fo a 5/16ths drill bit for a replacement bucking bar. also if you smooth out the left(look from the LHS of the bike) edge of the cam it has been known t cut down on wear of the bucking bar and also allow for much smoother actuation of the clutch.
     
  10. mapbike

    mapbike Active Member

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    Go and get you a grade 8 bolt that is 5/16" in dia. and 3-4" long cut the threads off and then messure up the bolt for the correct length and cut it again, grind a slight beveled edge on both ends and put some good high pressure moly grease on each end and you should be good for a long time before having to replace the bar or adjust the clutch cable.

    Hope this helps...
    Shan
     
  11. corgi1

    corgi1 New Member

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    The reason for the ball is to act as a bearing surface w/some grease,,,it has a smaller contact surface against the buck bar and the rod that it moves to push the clutch plate out,,,the other end of the buck bar has a wider contact surface against the clutch-arm cam and should not spin as soon as perssure is applied to the clutch arm enough to start disengaging the clutch,,,,As the clutch pucks wears down ,the clutch plate moves in toward the left side of the motor pushing the rod against the ball and this pushes the buck bar against the clutch arm cam,using up the freeplay and making the spinning buck bar wear against the un lubed cam that probebly also has road grit,that must be why we have to adjust the flower nut on a regular basis,,,original thought ,I wonder if the main spring on the clutch is too tight (hard to pull clutch lever) causing the clutch arm to be adjusted to the point of no free play too compensate for the stiffness of it,,,Also,crobo's #9 above
     
  12. 2door

    2door Moderator
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    This is very good advice. I go so far as to smooth and polish the bar and the cam leading edge using a buffing wheel and polishing compound. When finished the contacting surfaces look like chrome. A good high pressure grease applied to all surfaces where contact occures and you'll have a clutch that is easy to pull and will last a long time without wear in the linkage or need of constant adjustments.
    Tom
     
  13. Santa_cruz_loc

    Santa_cruz_loc New Member

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    Wow, you guys are on top of this kind of stuff.... Ok, I went to Ace and bought some moly grease and a 5\8 hardened steel drill bit and now I'm off to a friends who has the tools to make this a 2 hour project instead of an all day thing. I don't have the stamina to cut a drill bit like this with a hacksaw nor do I have a grinder/polisher. I will post again next week with some results on how well its working. Thanks again for all the info!!!! you guys rule!
     
  14. 2door

    2door Moderator
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    I hope you bought a 5/16" drill bit and not a 5/8". Also the length of the pin is extremely critical. If your original is not worn too badly use it as a guide for proper length.
    Tom
     
  15. Santa_cruz_loc

    Santa_cruz_loc New Member

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    I did mean a 5/16".....Anyway, I did everything advised including polishing the new pin to a mirror shine, slapped it all back together and took her out on a 20 mile ride, got home to see how it held up and there was a little shaving going on but minimal. I filed off any burs on the cam side, added more grease and took it out again of about another 20 miles and found NO SHAVING....
    Conclusion: this fix seems to work fine if you use the right materials and take your time to do it right.
    Thanks again guys!!!!!!!dance1
     
  16. 2door

    2door Moderator
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    Good for you. Have fun, ride safe.
    Tom
     
  17. Jumpa

    Jumpa New Member

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    Replacing the bucking bar with the butt end of 5/16 (HSS) High Speed steel drill bit is, without a doubt the best way to go.

    I learned this from 2-Door a couple years ago haven't had to change it out it out since, only to put it in a new motor and put the factory bar in stock

    I ride my bike EVERY single day unless there is more than 6" of snow on the ground.
    Thank You 2 Door
    ~Jump

    dance1
     
  18. 2door

    2door Moderator
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    You are quite welcome, Jump. Glad you're enjoying your bike. Have fun and please ride safe.

    Tom
     

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