Engine sprocket nut loosened

GoldenMotor.com

hbk3001

New Member
Jul 8, 2015
3
0
0
Cazenovia, NY
I was riding my bike today (Grubee Skyhawk) I'm about 1 tank through the break-in and I noticed the nut that holds the front motor sprocket on the engine came loose. Is it ok to use red locktite on this part, and is there a certain torque I should use? or can I tighten it right down?
 

Slogger

Member
Sep 8, 2014
544
4
18
nohio
I wouldn't use red, maybe blue. You may need to take it off sometime and that'll make it a lot easier. I never heard of one coming loose, I think if you tighten it up and use the special lockwasher behind it it should be fine.
A piece of copper, an old penny for instance, can be wedged in the gears on the other side to hold it still for tightening without any damage to the teeth.

The gear noise you hear is common, they're noisy little engines. There's a couple things you can do to cut the noise. A bit of grease (about the size of a pencil's eraser) put on the small gear will work its way onto all the teeth. SBP sells these weird sound deadening things that stick on inside the cover. They're like stiff tar that never hardens and deaden sound. I've had them since day one and I think they work, it's pretty quiet.

Don't overdo the grease, it can work its way onto your clutch plate and pads causing it to slip.

Let us know if your output shaft and sprocket's ok after you tighten that sprocket nut.
I would worry it might have gotten chewed up while it was loose.
Good luck to you!
 
Last edited:

crassius

Well-Known Member
Sep 30, 2012
4,032
158
63
USA
just tighten it down, probably left loose at factory - be sure to check that woodruff key under it is still good
 

crassius

Well-Known Member
Sep 30, 2012
4,032
158
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USA
if anyone in your area is working with these, they should have some lying around - both ends of the shaft take same nut
 

erikohman

New Member
May 24, 2016
3
0
0
37
Gothenburg, Sweden
Im currently having the same issue. I have tighten the nut, but after maybe 100 meters (yes i use the metric system, because. ) the nut gets loose again. And the motor is running but i have no movement. What i need to do then is to push the sprocket in agian, and tighten the nut, but same thing happens all over again. Anyone have an idea how to solve it? Thanks.
 

crassius

Well-Known Member
Sep 30, 2012
4,032
158
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USA
sounds more like the woodruff key is missing or it has been sheared off to be too short to hold the sprocket to the shaft
 

erikohman

New Member
May 24, 2016
3
0
0
37
Gothenburg, Sweden
Yes, it was the woodruff key that where only crumbs, Good thing was that my engine supplier sent me a new one for free. Now i will try to use loctite and maybe instead of the old spacer, an lockspacer instead. Its a kinda stupid design when the shaft isn't conical. And all the power is on the woodruff key.
 

crassius

Well-Known Member
Sep 30, 2012
4,032
158
63
USA
most newer shafts have a taper, but it is very slight - older 49cc motors had none, but had much stronger, rectangular keys