Vibration rpm limit

Discussion in 'Motorized Bicycle General Discussion' started by velardejose, Oct 17, 2008.

  1. velardejose

    velardejose New Member

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    Hi
    Is there anything we can do to reduce engine vibration above certain rpm?
    Why are other engines smoother than our china girls at high revs?
    I am new to two stroke engines, sorry if this is a dumb question
    Thanks in advance
     
  2. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Not very easily. If you have knowledge of and ability to perform a balance job, it would help.
    These engines are crude and pretty much unbalanced.
    They are 40's technology.
    They are made in China with little quality control.
    They are under 200 bucks.
     
  3. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    I have had a couple that were ALMOST as smooth as a Japanese dirt bike engine....others that would go 40 mph, but vibrated so bad, you could hardly hang on.

    Going to a 40T sprocket will help, so will balancing your wheels.

    I have gone to mounting all engines with small 1/16" thick sheets of lead between the mounts and the frame (4 pcs. total)...works like magic!
     
  4. OSCAR383

    OSCAR383 New Member

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    two things i have done and i love it is one cut up an old tube and wrap around the frame where you mount the engine to and the other is get a lower tooth count sprocket. lower rpm = less vibration
     
  5. Dominate.

    Dominate. New Member

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    any pics of said mods? I don't quite understand...lead? and a tube?
     
  6. Finfan

    Finfan New Member

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    Lead - the metal that bullets are made from. Chemical symbol Pb.

    Tube - rubber from an old inner tube.
     
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  7. bikesnipe

    bikesnipe New Member

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    Joe were might I find sheets of lead would like to try your tip thanks snipe pa.
     
  8. Potato_In_Exhaust

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    Good gawd, this thread is older than dirt!
     
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  9. crassius

    crassius Well-Known Member

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    yeah, in this decade, try a piece of PVC plumbing pipe between mount and frame for best results
     
  10. wildwood

    wildwood Member

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    I used the rag joint in between the motor and the rear mount with out a problem. The smaller sprocket is a wise choice 36 teeth and I still don't need to pedal up the hills of Pittsburgh..all that and some port cleaning plus a tight nkg plug boot 40mph on a 107 dollar motor kit off amazon. Damn thing runs better then the flying horse
     

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