vibration under part throttle

Discussion in 'Motorized Bicycle General Discussion' started by SledKicker, Jul 10, 2013.

  1. SledKicker

    SledKicker New Member

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    i've noticed my 66/80 beach cruiser runs way smoother at full throttle or very light throttle. at about half throttle or while cruising above 20mph it vibrates like crazy. what could be causing this or is it normal? goes away as soon as i give it the beans again.
     
  2. 2door

    2door Moderator
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    Is the engine mounted solid to the frame? Loose or ill fitting engine mounts can contribute to vibrations.
    Some vibrations are normal. Single cylinder 2 stroke engines vibrate. Its just the nature of the beast. Depending on how they are mounted determines how much of that vibration is transfered or absorbed by the frame.

    Tom
     
  3. SledKicker

    SledKicker New Member

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    i will recheck my mounts, thank you.

    i just went on a long test ride. lots of power, but under part throttle it 4 cycles. runs great WFO
     
  4. maniac57

    maniac57 Old, Fat, and still faster than you

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    That's what you want for best overall engine life. Tuning for max power is risky and expensive if you mess up and go too far...
    Love her for what she is and don't expect her to break speed records and you will be happier in the end.
    Just sayin
     
  5. SledKicker

    SledKicker New Member

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    Where did you get that i want a speed demon? I am complaining about a cruising condition :)

    Not that blowing a motor is a huge deal when parts are this cheap. Ive all but stopped playing with full motorcycles since finding this hobby!
     
  6. maniac57

    maniac57 Old, Fat, and still faster than you

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    Not hacking on you, just meant a bit of four-stroking at steady throttle is about right as far as jetting.
    Pulls clean under acceleration then it's good.
    Go leaner till you like it if you are not worried about wear and engine life.
     
  7. fatdaddy

    fatdaddy New Member

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    Mine 4 strokes some too. But at WOT it SINGS to me. I'm not gonna worry about it though, it runs good enough and is hitting around 35mph. 2door is probably right about the mounts. A loose mount will make yer hands all tingly with all the vibration.
    fatdaddy
     
  8. SledKicker

    SledKicker New Member

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    Oh i didnt know 4 stroking at part throttle was ok. Thanks guys!
     
  9. fatdaddy

    fatdaddy New Member

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    You could probably work it out with A LOT of experimenting with the porting, carb tuning, fuel mix, ect, ect. It's probably running just a little rich, which is better than running too lean. If it has a good pull all the way to the top end I'd leave it alone and just enjoy the ride. Just my humble opinion.
    I would be more worried about the vibration. I would replace the chinese mount studs and nuts with a better grade and make sure they are TIGHT.
    fatdaddy.
     
    #9 fatdaddy, Jul 11, 2013
    Last edited: Jul 11, 2013
  10. SledKicker

    SledKicker New Member

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    Thats exactly what i will do then. Thank you
     

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