BAD Vibrationat 30+?

Discussion in 'Motorized Bicycle General Discussion' started by kornbread, Feb 11, 2010.

  1. Vistaman73

    Vistaman73 Chat Box Junkie

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    Cruising up a slight hill is zero vibration. Going down hill is crazy vibration, of course, I'm going faster. I have reached top speed before and it does not smooth out the vibration just gets to a higher frequency. So, this is how it runs. BTW, it's done this from day one. It has not gotten any worse or any better. :(

    under 15 uphill=perfect
    under 15 flat=ok
    under 15 downhil=ok
    around 15 uphill=fine
    over 15 flat=not really rideable
    over 15 downhill= crazy scary
    top speed=crazy scary
     
    #21 Vistaman73, Feb 12, 2010
    Last edited: Feb 12, 2010
  2. Creative Engineering

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    Bad crank for sure Vistaman!

    Jim
     
  3. Vistaman73

    Vistaman73 Chat Box Junkie

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    Oh well, I will order one from one the side sites, I know one has it but I forgot which. I hope this will not be a hard replacement. I get the feeling it will be. Out of all the normal engines, I get the one thats screwed up. :facepalm: God, I hate China right now.
     
  4. Xiodinc

    Xiodinc New Member

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    get some rubber pedals to make up for the vibrations!
     
  5. bairdco

    bairdco a guy who makes cool bikes

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    xiodinc, the first time i read about rubber pedals (probably from you,) i thought, "pfffft. whatever."

    then i switched out my rubber cruiser pedals and put some old steel vintage HKS rat trap pedals on.

    you're right.

    my bike doesn't vibrate hardly at all, but when i wear my old converse, i can definitely feel it more.
     
  6. Nashville Kat

    Nashville Kat Active Member

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    two things really got of rid of most of the unpleasant vibration I had when I first built up a new Micargi cruiser:

    1. Narrow street tires- the straight tread of more narrow 1.75 tires (only $10 each and used the same tubes) gave a much smoother and easier roll- knobby tires must be even worse on the road,

    2. A bigger gear- going from the stock 44 down to a 36 on the back gave me the same cruising speed with a lot less throttle and motor revs. Made all the dfference really.

    I also found that putting some BMX bars that are perpendicular to the frame gives amuch better grip than cruiser moon bars.

    I've since gone even more narrow on the frontwith an alloy 27 x 1 1/4 wheel

    .trk
     

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    #26 Nashville Kat, Feb 12, 2010
    Last edited: Feb 12, 2010
  7. Xiodinc

    Xiodinc New Member

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    i got some nice rubber pedal on, and the dampener kit from pirate cycles. going 40 top with 44t sprocket, no vibrations. i have some straight bars too.

    They look like BMX, but they don't have the top cross bar
     
  8. kornbread

    kornbread New Member

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    I'm running a 26" rim with a 44t sproket and my oil mix is 4oz-1gl. and yes i looked at the plug the other day and it was brown on it but i never sized it to specs and i went and bought a gap toll and set it to .6
    my book on it tells me to gap it at .6-.7drn2
     
  9. bairdco

    bairdco a guy who makes cool bikes

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    say what!? the plug gap should be between .020 and .030!
     
  10. kornbread

    kornbread New Member

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    well i just set it but haven't run it yet
     
  11. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    You should just be happy your bike will actually go 30 mph. Some won't...a lot of them won't.

    Vistaman73- We used to true up the cranks of hardley ablesons with a large mallet and a hardwood wedge. Yes, that's right from the shop manual, look it up, it's worth a shot.
     
  12. Creative Engineering

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    kornbread,

    With your set-up: Joe's right!

    Out of the box, with a rider that weighs around 180lbs...30-32 is absolute tops.

    This is assuming the engine will rev to just over 7000rpm. As Joe said, many of them won't.

    If you are able to reach 30mph, there's nothing wrong with the engine.

    You will need to step down to a 38-40T sprocket if you want to cruise at 30 without the excessive vibration. You can also try to get more rpm out of your engine through modifications, but it will likely get expensive.

    If your engine is fairly torquey, get a smaller rear sprocket and your engine rpm will drop out of the vibration zone for the same mph.

    laff...Joe, that is what my dad called a calibrated "whack", and yes it does work!

    Vistaman, you could take it to a motorcycle shop that is equipped to rebuild engines. They will have the "V"-blocks and dial indicator to check for trueness after tweaking it.

    Jim
     
  13. kornbread

    kornbread New Member

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    hey thanks guys i will get around to messing with it later and i'll reset my spark gapand i'll keep you guys updateddrn2
     
  14. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    A 40:1 mix will smooth things out over a 16 or 20:1 mix too.
     
  15. kornbread

    kornbread New Member

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    40:1 is what to a Gallon?

    I'm now using 4oz to 1 gal. but i'm using Super Tech Universal 2-cycle oil from wal-mart should i change to a better 2 cycle oil?If so what do you recommend?
    drn2
     
  16. Xiodinc

    Xiodinc New Member

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    i use a 32:1 but will switch after 2 more tanks to a 40:1
     
  17. kornbread

    kornbread New Member

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    I also just ordered the Denso spark plug IWF20 and i'm waiting for it.drn2
     
  18. kornbread

    kornbread New Member

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    and what is 40:1 on oz-gal?
     
  19. Cabinfever1977

    Cabinfever1977 New Member

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    That would be 3.2oz oil per gallon of gas for 40:1 .
     
  20. 2door

    2door Moderator
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    Didn't the Beach Boys do a song with this title?
    Tom
     

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