Reducing Vibrations at High Speeds.

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

  1. exavid

    exavid New Member

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    Rubber dampers between the fins comes factory installed on some of the older air cooled motorcycles and it does help hold down the noise and vibes. I'd forgotten about it. I'll try it.
     
  2. mmmmudd

    mmmmudd New Member

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    OMG I'm so glad I'm not the only person with parts of their anatomy going numb. . . I haven't put a lot of miles on the lil bike, but I've already had all manor of parts rattle loose like it was an old school Triumph. I've definitely got to invest in some more loc-tite! No seriously I've never thought of my old Harley as smooth before. . . Who knew?

    I figured, simply because all things have been tried, that some one's built one of these kits with a version of the rubber mounts like come on the new Harleys. I was imagining utilising the bushing found on new chain saws or roller blade wheels I dunno. . .

    Years ago I had an old Yamaha RD, came buzzing up to the drive after riding for a few hours, only to find my legs had gone to sleep. I leaned the bike over to put the kickstand down and "legs no move!" Mudd and bike both landed on the ground with a discordant, ker-plop! Funny how I'd blocked that memory out for so many years, LOL
     
  3. 2door

    2door Moderator
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    Do not mount the motor in rubber. This has been discussed here over and over. By doing so you are NOT eliminating the source of the vibrations but simply isolating it to the mounts and the mounting fasteners. It is not a 4 stroke Harley, or a Honda, or a Chevrolet or a Cadillac. It is a 2 stroke, single cylinder engine that will produce vibrations.
    Tom
     
  4. mmmmudd

    mmmmudd New Member

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    @2door
    I wouldn't even imagine rubber mounts actually stopping the screaming motor from vibrating, any more than it does on machines built on a bigger scale. I guess the big difference between a big machine and a small one is high frequency vibration vs low frequency. For right now I'm going with gloves and vibration isolators (in the form of springs) on my seat. I guess in a perfect world tiny cheap engines would be perfectly balanced, but until then. .bzzzzzzzzzz
     
  5. bitsnpieces

    bitsnpieces New Member

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    I wish I known this earlier as when I tried using rubber, it just felt too thick and stiff for me to really think it would dampen the vibrations; front studs snapped.

    I'm currently using cut outs from an old thick mouse pad I had; will see how that goes when I get a chance to do another good long ride.
    So far they felt good when I did a quick test after putting my bike together again to make sure I've fastened everything correctly and it was all working.
     
  6. spideyman

    spideyman New Member

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    I thought mine was vibrating to pieces aswell untill I realized my rear axle was bent which caused all kinds of problems as you can imagine!
     
  7. mmmmudd

    mmmmudd New Member

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    AW MAN! Spidey,

    How'd you discover the errant axle? Did ya have one of those Aha! moments?
     
  8. fm2200

    fm2200 New Member

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    Try using pipe insulation, there are different types of foam. They can last for a good 6 months, it really depends on how much you ride. It's really cheap compared to bicycle foam grips and it works pretty good.
     
  9. Sideshowbob

    Sideshowbob New Member

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    I'm with him on this-- my land yaght cruzer has goodies dangling all over w/ 66cc china girl, 40t sprocket,old carb, std exhaust does 35 before it starts vibrating. I can cruz 30 all day but I like 25, and I've hit 40 (very sketchy) I just have small hard rubber strips between mounts and frame nice and tight w/loktite. I get vibration at high rpm not speed, these little motors seem to like 3500rpm a lot better than 6000. come on its made out of melted beer cans. We seem to squeeze a lot out of them now. I think firmer mounts make them shake less. If its all loose hanging on big rubber doughnuts it seems it would shake more on the mounts.
     
  10. buzbikebklyn1

    buzbikebklyn1 New Member

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    Barsnake.com ©2010 Barsnake LLC
    Order from- [email protected] or contact them at: 541-416-1120

    I've found that these really help with the numb hands bit.
    Since the smallest diameter one is 7/8ths, If the handlebars appear to be smaller than normal on the inside diameter, or handlebars appear to have sharper than normal bends you may wish to pre-heat the Barsnake in hot water to allow easier installation!
    I like this version- Bar Snake Model LV-4. its good for bars with sharp bends or internal cables.
    You MIGHT want to remove the bar from the bike and put it in a vise to make it easier.
    THEY WORK!
    BBB
     
    #30 buzbikebklyn1, Feb 12, 2011
    Last edited: Feb 12, 2011
  11. Sideshowbob

    Sideshowbob New Member

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    For bar vibration I guess you could just use spraycan expanding foam sealant to achive the barsnake effect for less cost. What specific kind of CDI are you using I've heard that the kind on KZ 80 Kawasaki 2 stroke work great? I would like to try one with an internal rpm/retard/advance feature.
     
  12. KCvale

    KCvale Well-Known Member

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    jaguar, I looked over your tech notes on your web page, interesting well documented idea's for intake for sure.

    But aren't you kind of missing the biggest easiest way to add half a horse to where you want the power? An Expansion Chamber exhaust?

    You want as much air with the richest air/fuel mix you can burn clean not just input, but back-charged with an expansion chamber.

    Your example bike has a stock pipe.
    Try a SickBikes Xchamber and you can throw all that out and start looking at getting more air through ;-}
     
  13. buzbikebklyn1

    buzbikebklyn1 New Member

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    Jaguar, I read that hop up page on port timing and other performance tricks... thanks, very informative.
    Can I ask exactly which CDI you use?
    I'm working on a method to advance the rotor magnet more accurately yet still be index able.The cone/magnet type arrangement just doesn't seem secure enough to me.
    BBB
     
  14. buzbikebklyn1

    buzbikebklyn1 New Member

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    cool... thanks
    BBB
     
  15. Rocket Bike

    Rocket Bike New Member

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    I solved a lot of that same problem by putting higher bars on my bike.
    As soon as I stopped leaning on my hands, they didn't get so numb.
     

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    #35 Rocket Bike, Feb 14, 2011
    Last edited: Feb 14, 2011
  16. jwmorrow

    jwmorrow New Member

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    take an old brake leaver turn it towards u and hook up the cable. now you have a thumb throttle. you might have to grind it down,
     
  17. KCvale

    KCvale Well-Known Member

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    I cut the stock hard grip off the throttle and replace both grips BMX foam grips on most every build.

    Pull the throttle barrel out, cut off the grip, cut your foam grip to length and soak it in some hot soapy water and then just force it on with a kind of 'milking' action.
    Foam grips are a pleasure to ride with.

    A good front mount helps too, sick bikes has them, just measure your downtube so you get the right sized one.
     
  18. Jumpa

    Jumpa New Member

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    I cut up an old bicycle tire tube and wrapped it around both points where the motor mounts go I actually super glued the rubber pieces to the frame tubes so I could avoid over lapping the rubber and I didn't want the bulk of electrical tape I did this on my second build an it has considerable less vibration than the first build , I also wrapped rubber tube around the bar before installing my gas tank keeps it from moving around and cuts down on a lot of vibration we get from there as well .

    I have this awesome front suspension fork set up. "R/S or Rockshox as it's called" However it doesn't fit my bike so I just look at it and wish . However if I get that mig welder & plasma cutter I want for Christmas.... hmmmm "YEA RIGHT" ..

    P.S. I saw someone say they used a screw driver to keep the clutch handle in while idling I just cut a chunk of Tire tube and fit it over the left hand bar grip roll it over the clutch handle as its pulled in works great for me & I don't have to worry about it vibrating out like one would a screw driver. gezzz I guess I use old rubber bike tubes for almost everything....They do make good thick bungee cords as well . I even put small chunks on the bottom of my desk top PC to cut down the vibration on this bad boy! I also used tube chunks on the bottom of the wife's Keurig coffee machine that thing would sound like the space shuttle taking off at 5 am
     
    #38 Jumpa, Oct 7, 2012
    Last edited: Oct 7, 2012
  19. 2door

    2door Moderator
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    Jumpa,
    Just to repeat what has been said here many times; you are not eliminating vibrations by rubber mounting the engine but only transfering the vibrations to the engine mounts and fasteners. Keep a close watch on these areas if you continue to ride the bike with rubber between the engine and frame.

    Tom
     
  20. KCvale

    KCvale Well-Known Member

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    There is one simple test.
    Hold your top bar with one hand, hold the motor head with the other.
    Now push and pull the motor as hard as you can back and forth.
    Does it move? If so it will fail and your mount is a hazard.
     

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