Reducing Vibrations at High Speeds.

Discussion in 'Motorized Bicycle General Discussion' started by ...ladies, Jan 28, 2009.

  1. ...ladies

    ...ladies New Member

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    How can a reduce the vibrations? Long rides and high speeds end up stinging my hands before long. How do i fix this? Thanks,


    -Nick
     
  2. Ghost0

    Ghost0 New Member

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    Front suspension
    Better grips
    Smaller rear sprocket or Shift Kit to reduce engine rpm
    Weighted handle bars
    Swept back cruiser style handle bars
    Balance engine
    Improve engine mounts

    If anyone has any others lets hear it.
     
  3. jasonh

    jasonh New Member

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    I think you hit the nail on the head, Ghost0. I would try things in this order:

    Improve engine mounts
    Smaller rear sprocket or Shift Kit to reduce engine rpm
    Swept back cruiser style handle bars
    Better grips
    Weighted handle bars
    Front suspension
    Balance engine
     
  4. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Mount the engine with lead sheet. Fill the bars with lead shot.
    Uh, don't run it so fast. ;)
     
  5. ...ladies

    ...ladies New Member

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    Have front suspension, crappy, but its there.
    I have the corny grips that they all game with. Where can i get a different throttle grip?
    I need the big sprocket for the hills :D lol
    Weighted handle bars? How does this work exactly..
    Balance engine... simple as it sounds?
    Improve mounts, thats what i was figuring, how would i go about doing that?
     
  6. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Weighted bars- fill them with lead shot, or use bar end weights.
    Balance the engine- yes if you know what you are doing......
    I mount my engines with a sheet of thing lead between the mount and the bike frame, and also between the "C" clamp and the frame.
     
  7. ...ladies

    ...ladies New Member

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    Balancing the engine? Just so its straight with the sprocket, and both clamps are completely touching (only happened perfect on this one bike) what else is there?
     
  8. Ghost0

    Ghost0 New Member

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    What we mean by balancing the engine is removing your crankshaft, rod and piston assembly and have it balanced. This is only for those that know what they are doing. This is the reason that your engine vibrates in the first place.
     
  9. ...ladies

    ...ladies New Member

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    Ah ic, i didn't know you guys got that in depth with these little things lol. I'll stick with the lead shot and hard rubber motor mounts lol
     
  10. hill climber

    hill climber New Member

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    my bike vibrated like crazy. i did the engine porting, lowered the intake port and raised th exhaust port,as posted by here. this not only gives you more power but smoothed out the motor considerably. way less vibration, way more power.
     
  11. jasonh

    jasonh New Member

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    I also hear that the 70's vibrate much more than the 50's. Can't confirm though, as I've never ridden a 50. It also depends on where you get your motor from, as quality can vary.

    I had straight bars and the vibration was killer. So I got some big riser bars and it was way smoother. Then the cheap bar bent so I went back to the straight bar...vibration sucks.
     
  12. ...ladies

    ...ladies New Member

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    Ah okay. Ya i'v got the so called 80cc off ebay. Straight bars.. Birthday is coming up and i had planned on new seat and wheels. Maybe just get mine trued and get some curved handlebars..
     
  13. exavid

    exavid New Member

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    Vibration is an interesting problem. I have two 49cc motor bikes. One is a two cycle on a Schwinn mountain bike, the other is a four cycle on a Schwinn Cruiser. The two cycle is pretty smooth, I have a pull back bar on the bike and don't feel much vibration at any speed in the bars or seat. On the cruiser I get a pretty strong buzz in both seat and bars. I have a 44 tooth on the two stroke and a 50 on the four. I've ordered a 44 for the four stroke which should here Monday. I'm hoping that the lower rpms at cruising speed will reduce the vibes a bit. At least it will slow the engine a bit which sounds like it's really churning. It's hard to be sure since fan cooled engines always sound like they're running faster than non fan equipped ones. So far I have about 100 miles on the two stroke and 20 on the four stroke. Both are running well, I like the centrifugal clutch and pull cord on the four stroke but find the lighter two stroke bike a bit more fun to ride. One change I'm planning on the four stroke is to build a better engine mount I plan on bolting two pieces of aluminum angle (can't weld it the frame is aluminum) side by side with the flanges outward to the bike frame. A couple of holes in the sides of the frame at that point won't affect the strength much since lateral holes in that area are really in a neutral stress point. If that isn't enough my next plan will be rubber shock mounts. One way or another I'm going to make the four stroke smoother and quieter..trk
     
  14. civlized

    civlized New Member

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    http://motorbicycling.com/f37/anti-...s-us-8123.html?highlight=anti+vibration+mount
    I know it's a little different, but this worked great. Maybe it will help a little.
     
  15. corgi1

    corgi1 New Member

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    Someone was building a 4 stroke w/out the fins or shroud someplace in these blogs and figured air flow would cool it,,,thought of this when exavid mentioned the viabration in his
     
  16. exavid

    exavid New Member

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    These little engines can get pretty hot so I don't want to take off the fan and shroud though that would give a little more HP to turn the bike wheels. I plan on fabricating a better mounting plate to put the engine on and some rubber mounts between the engine and plate. The drawing Neat Times posted awhile back is pretty much what I had in mind between the plate and engine. I had a similar mount on a 65hp Rotax in my home built Avid Flyer airplane which did a good job reducing the high frequency vibes from the engine.
     
  17. Dan

    Dan Staff
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    Found these gloves that are made for working with a jack-hammer. They look like bicycle gloves and are fingerless but are heavily padded at the palms. Uber cool and work great but costly for gloves. Trying to buy a case of em. Just breaking in a 2 smoker for my nephews. Put it on an old steel Haro so it fit perfect to the frame. Right an' tight but the handle bars are at the same height as the seat so your leaning on your hands.

    Really helped.

    I had forgot how much fun the 2 smokers are! Gonna have to get me a SBP shift kit

    Exavid, Tyrslider makes custom 4 stroke mounts. Ya give him 3 dimensions and he cuts it out of a block of aluminum. Purty amazing. He is my partner but don't mean to do the shameless promotion thing, just chating
     
  18. Nashville Kat

    Nashville Kat Active Member

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    Thin tires work great! 1.75 street tread- we rode those when I was a kid- I got some for 10 a tire at a shop last summer

    the 36 rear sprock cuts down the revs too

    I use pipe insulation styrofoam for motor mounts

    and the front shock fork and suspension post work well too

    I even went to the 27 front, the short billet intake is a great performance boost in carburetion for less than $15

    .trk
     

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    #18 Nashville Kat, Feb 22, 2010
    Last edited: Feb 22, 2010
  19. exavid

    exavid New Member

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    My two stroke Schwinn runs great, it tops out a bit over 30mph with a 40T sprocket. There's little vibration on that bike, I wish I could say the same for the four stroke.
     
  20. fall_down_stand_up

    fall_down_stand_up New Member

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    Here is a little trick I learned off one someone on this site awile back....Put peices of a old bicyle tire inbetween the fins and it makes a great difference in vibration....Here is a pic of me and my bike and you can see how it put the rubber inbetween the fins...
    http://img691.imageshack.us/img691/7082/meandoldbike.jpg
     

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