Screeching noise

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?
 
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.
 

Pablo

Master Bike Builder & Forum Sponsor
Dec 28, 2007
3,666
6
38
Duvall, WA PNW
www.sickbikeparts.com
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........
 

misteright1_99

New Member
Mar 21, 2008
716
2
0
Treasure Coast, Florida
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?
 

victoreperez

New Member
Jun 25, 2008
10
0
0
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
 
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.
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,843
241
63
up north now
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?

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.
 

jasonh

New Member
Jun 23, 2008
1,590
0
0
37
Longmont, CO
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.
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,843
241
63
up north now
I have exactly the same problem. Does anyone know what the fix is?
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.