Help With Strange Metallic Noise - Video Included :)


Local time
3:48 PM
Jul 18, 2008
Franklin, TN
Just finished a build and the bike runs good but has a high pitched metallic kind of noise. I have made sure the clutch isnt hitting anything as far as the housing - anyone else had anything like this ?

It is driving me a bit nuts wondering what is causing that. The bike seems to work great just that sound ..........

Oh and yes I am replacing the motor mount bolt thus the motor vibration :rolleyes:

Thanks !

Is there the noise when the motor is mounted properly?
Are the gears lubricated?
Anything loose in the muffler?
Is there the noise when the motor is mounted properly?
Are the gears lubricated?
Anything loose in the muffler?

Yes, same noise when the motor is cranked down and tight.

Gears are lubicated.

Have done the cardboard trick on the cover

seems to be worse with the clutch disengaged but it doesnt seem to increse with rpm - when I rev it up it does seem to somewhat increase.

havent checked the mufler but it really seems to be coming from something in the gearbox. Bike has about 10 miles on it so possibly after breaking it in it might quiet down but I doubt it.

It almost sounds like a ringing sound when it is sitting there idling but not all the time. I havent taken the cluch completely off just the plate and checked that adjustment of the clutch. It rides fine except for the chattering, metallic, what the #$#$% is that noise :eek:
OK, Pulled off the clutch plate and assm. I found marks on the housing and Im sure they are from the gear contacting the housing. I took a small amount of material from the inner edge of the housing - reassembled but still has a freakin sound. I think I will take it apart again and remove more aluminum until it quiets itelf. Wonder if I should try and remove a tad off the gear ?


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my bike has the same noise

i know this is a very old thread. but i stubled upon it. and my engine is making the same noise! it seems like it has been getting louder. i take the cover off and first i was puting break in oil on the gears. (lucas break in oil), now i have switched to synthetic mobil 1 heavy grease. it seems after i either put the grease or the break in oil on the gears it would quiet it down for a mile or 2 but then gradually come back. and each time i do this it seems to come back louder and louder. it doesnt look like anything is rubbing, and the cluth isnt slipping. so im not sure what it is. but its just like in tha video. a metallic whirling, grating sound, coming from the clutch plate/gear area. my engine only has about 25 miles on it.. so is it maybe just a sound that happens during break in until something seats properly or what??
My transmission gears sound like a gear driven cam setup in a hot rod muscle car.
No worries though. It has never caused any failures yet.
My second Grubee 80cc does the same thing. Runs great when cold, heats up and gets loud, also, power falls off. Called Piston Bikes many times, still awaiting a resolve.