Engine vibrations bad for the frame?

Discussion in 'Motorized Bicycle General Discussion' started by loangwang, Jan 30, 2011.

  1. loangwang

    loangwang New Member

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    I just installed a grubee skyhawk 66cc 2 stroke motor onto my mountain bike and it vibrates a lot. My hand feels a bit numb after 10 mins of riding it on the road. Is this a common problem? and how bad is this engine vibration on the bike frame? and i saw this item for sale Sick Bike Parts would it work? thanks!:-||
     
  2. 2door

    2door Moderator
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    Welcome to the forum. You've found the right place for help and advice.

    Vibration is a relative term. What some call, severe, another might say is normal. Some are worse than others but all two stroke, single cylinder engines will vibrate to some extent. Just the nature of the beast.

    Is your engine mounted solid to the frame? Adding any resilient material, rubber, tape, old innertubes etc, to the mounts will increase vibration and eventually compromise the mounting fasteners and other parts. A solidly mounted engine will not vibrate as bad as one soft mounted. There are things that can be done to make a more comfortable ride such as soft grips for your handlebars, proper chain tension and alignment and most engines will run better (smoother) after they're fully broke in.
    Good luck, ride safe.
    Tom
     
  3. muddybike

    muddybike New Member

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    If the vibs are severe, make sure you check your spokes to see if any have become loose.
    Most times that i find the vibs are real bad a spoke or 2 needs some love.
     
  4. loangwang

    loangwang New Member

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    2door- The down tube on my bike was too thick for the clamp that came with the kit to mount with the engine so I custom made a small sheet of aluminum and a plate of wood. Both are flat pieces and so i mounted the aluminum on top of the down tube and the small wooden plate on top of the aluminum and then mounted the engine on top of the wood so basically the engine is mounted on a flat surface very tightly. And as for the seat tube mounting part for the engine, I just wraped a thin layer of rubber tire around the seat tube where I'm going to mount the engine to so it doesn't get scratched up. You think the down tube mount might be causing the bad vibrations? and does the vibrations damage the bike frame?
     
  5. 2door

    2door Moderator
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    The damage to the frame will be a result of the engine being able to move at the points of contact. If the engine is bolted solidly to the frame, no rubber, then it cannot move, hence, no wear. Yes, paint damage can result and some have wrapped the contact points with electrical tape, just enough to protect the paint, not layers and layers.
    As I stated above; the more solid the engine is mounted, the less you'll feel the engine vibrations.
    'm not in favor of wood as an engine mounting material. It will compress over time and allow for movement/vibration. Try to get rid of the wood and opt for metal heavy enough to hold the engine securely.
    Tom
     
  6. flybytaco

    flybytaco Metal Molding Madman

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    solid mounting def seems to help the vibe also ive noticed the angle of the motor helps i had a engine that vibed so badly i remounted it in a diffrent angle and it was 50% better
     
  7. msrfan

    msrfan Well-Known Member

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    I had 2 motors in a row that vibrated so bad no matter how solid the mounting. I ended up balancing the crank and that fixed the problem.
     

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