Rrrruuuurrrr, ruuurrrrr, noise?

GoldenMotor.com
S

scribling

New Member
Mar 31, 2014
36
0
0
Simi Valley
I have a very strange rrruuuurrrr, ruuurrrrr, ruuurrrr noise in my engine. I put it together 2 weeks ago and it's been there since day 1. It doesn't like to idle, unless high rpm. It vibrates a lot. The noise is about equal in loudness to the sound of the motor increasing with the speed of the bike. It's not the clutch. I ran without the clutch cover ... not it.

Everything would be just about perfect if I could get rid of this noise. As it is, I just don't trust the bike. I feel like it's going to break down any minute.

Anyone else have this noise? Know what it is?
More importantly, know how to fix it?
 
maniac57

maniac57

Old, Fat, and still faster than you
Oct 8, 2011
4,484
22
0
memphis Tn
Re: Rrrruuuurrrr, ruuurrrrr, ruuurrrr ...

Chain rubbing inside clutch cover? Pull it and check for rub marks. Clearance as needed.
Tire rubbing? Check and adjust as needed.
Clutch release parts (ball, bucking bar) greased well? Grease.
 
2door

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
Re: Rrrruuuurrrr, ruuurrrrr, ruuurrrr ...

Is this your first Chinese 2 stroke build? Some are noisier than others but they all have a certain noise problem. Gear noise, if that's what it sounds like could be an indication that the primary and secondary gears behind the right side cover need lubrication.

The clutch actuating components also require lube. The bucking bar and ball bearing in the center of the output shaft/sprocket could be dry and in need of grease.

There are several sources for noise from these little engines. You'll have to experiment and see where it is coming from. Exhaust gasket failure is common and well as normal intake sounds.

A pulsating noise could be the result of a bad primary gear. I've seen them that were not drill correctly and they wobbled on the shaft and meshed wrong with the secondary gear. They were really noisy until that small gear was replaced.

Tom
 
2door

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
I hear the sound you are describing. Sounds like gear noise or clutch ball bearing and bucking bar.
Did you check the gears for lubrication? It only take s dab of good bearing grease smeared over the teeth. Don't over do it because the excess grease will get onto the clutch friction pads.

Also as I posted above the clutch actuating parts need lube too.

Just a word of caution. Do some reading here on the potential hazards of fenders. They can bite you.

Tom
 
mrfubs

mrfubs

Member
Jun 13, 2013
306
12
18
michigan
It is not your clutch or any of that. Your crankshaft is out of tru. When the chinese machined these crank halfs the are using a lathe with a worn out chuck. The shaft your little drive gear rides on is not rotatating in a perfect cicricle like it should, it is wowing from lack of tru-ness nothing you can do about it unless you have a lathe.


It is also possible your sprocket on your wheel is not centered.
 
Kioshk

Kioshk

Active Member
Oct 21, 2012
1,152
10
38
Connecticut
My first thought is clutch-pad-cover grinding. Did you check the inside of the cover for wear? I've had it happen in two situations: when the crankshaft's wormgear screw comes loose and then the clutchpad assembly's tripod posts hit the cover.

Your neighbors must loooooove you. "Where are the children?!? That maniac with the aviator-goggles is at it again!"
 
mrfubs

mrfubs

Member
Jun 13, 2013
306
12
18
michigan
These cranks are only worth $25 more than likely if you took just the crank to a shop it wouldnt be very cheap, if you dont fix bearing wont last las long but will still probably last as long as the res of the engine its not a big concern. Its only a concern for racers that are spinning high rpm.
 
mrfubs

mrfubs

Member
Jun 13, 2013
306
12
18
michigan
I stand corrected. I recently pressed my crank apart to stuff my balance holes with alloy rod and i found a place 10 mins from me that charges $55 to press it together and true it +10$ to weld the pin. A different place about a hr from me wanted 70-90 +35 to weld pin
 
You must log in or register to reply here.
Top Bottom