Screeching noise

Discussion in 'Motorized Bicycle General Discussion' started by boogerballs, Jun 16, 2008.

  1. boogerballs

    boogerballs New Member

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    Ok, so I've got my 48cc mounted and running. It accelerates fine but as soon as I let off the gas it makes this horrible screeching noise. The clutch is engaged so I don't understand it. It "sounds" like it is slipping but doesn't feel like it is. Everything "feels" fine. A very annoying sound, that. Any ideas?
     
  2. Pablo

    Pablo Master Bike Builder & Forum Sponsor

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    Could be clutch gears chewing on clutch case. Remove cover and ride.
     
  3. boogerballs

    boogerballs New Member

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    Nope, that wasn't it. Nor was the noise coming from the little idler pulley. I think the noise sounds like it is coming from inside the engine.
    I took off the clutch cover and didn't see any shavings at all. There was some clutch friction material (I'm guessing). I left it off for some runs down the street and the noise was still there. Then I lubricated the idler pulley and it still didn't change the sound.
     
  4. Pablo

    Pablo Master Bike Builder & Forum Sponsor

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    Inside the engine? So it follows the engine RPM? Under load or just sitting there revving?
     
  5. boogerballs

    boogerballs New Member

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    The noise only occurs when coasting with no gas on and clutch engaged or under decceleration.
     
  6. Pablo

    Pablo Master Bike Builder & Forum Sponsor

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    Have you greased your clutch gears? Rod ball? And little clutch bearings?
     
  7. boogerballs

    boogerballs New Member

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    If you mean the large gear meshing with the small gear on the crank, yes. Yes on the rod ball as well. What is the little clutch bearing? Haven't heard of that one. By the way, thanks Pablo, for the help.
     
  8. Pablo

    Pablo Master Bike Builder & Forum Sponsor

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    Remove your outer clutch plate and there should be 3 small small holes about half way between the center and the teeth. This is where you can grease the little bearings....some engines have this access, some don't I'm starting to believe........
     
  9. misteright1_99

    misteright1_99 New Member

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    Yea your right Pablo cause mine doesnt. I have a Grubee 48cc roundhead Spitfire, and there a no holes just the alignment pins for clutch plate. Would adding grease from the clutch cable adjustment hole get to ball bearings in clutch?
     
  10. Pablo

    Pablo Master Bike Builder & Forum Sponsor

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    I doubt it.....I'm running out of ideas!

    Norm!!!!!
     
  11. victoreperez

    victoreperez New Member

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    Boogerballs...any luck finding out what's doing the noise?...just finished with a 48 cc install and the same thing is happening...when i stop accelerating this horrible screech comes on...no slippage and the sound goes away when i pull the clutch in...please post if you found anything at all wit the above suggestions...thanks
     
  12. boogerballs

    boogerballs New Member

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    No, for the time being I'm just living with it. Doesn't seem to affect anything else. Acceleration is fine and it idles great. If I go too fast like downhill and overrev the engine it really starts to vibrate. Like hard to hold onto the handlebar-type vibrate. I think I will try the grease down the clutch stop bolt hole first, then some sound deadening in the side cover (although I don't think that is where the noise is coming from). I will report back here if I find anything.
     
  13. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    I shot some chain lube down there...it goes in liquid then turns to chain grease after a few minutes.

    I think the OP is experiencing gear whine....some do it more than others.
     
  14. jasonh

    jasonh New Member

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    I think it's just the whine from the gears. If you want to quiet it down, you can put a sound-deadening material on the clutch cover. People use mouse pads, dynamat, plastic, etc.

    That or when you let off the throttle, disengage the clutch. You probably won't hear it then.
     
  15. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Gear whine ranges from none to extreme. I've had both. The military bike, no matter how much, or what kind of grease I used was LOUD. The last build was almost noiseless. The rest were somewhere in the middle. Use a mousepad to cover the right side clutch cover, you'll be amazed.
     

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