Knocking sound has me Lost

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jwmorrow

New Member
Jul 9, 2012
7
0
0
harrisburg pa
Ok I have a knocking sound on Grubee SkyHawk 66/80 made in 2012. I noticed it while riding the other day. It dose not happen when the motor and bike are sitting at idle or if i give it gas. the sound starts when I start moving forward and let the cluch out. But it also dose it when the motor is off and I am peddling. The sound is coming from the front of the motor.

I checked the sprocket beaing it ok. There is no play in the magneto. The bearing in the piston is ok little to no play. I took the motor off and realined it. no rubber its direct to the frame( cranbrooke). i also checked the wheels spokes and crank all ok.

What am i missing. Oh and it runs fine. dose 27 up inclines and 30 on flat roads.
 
biknut

biknut

Well-Known Member
Sep 28, 2010
6,632
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83
Dallas
Make sure your drive chain isn't too tight, or too lose. Check your power side sprocket alinment
 
biknut

biknut

Well-Known Member
Sep 28, 2010
6,632
411
83
Dallas
jwmorrow said:
It looks straight. is there any tricks to be more sure. there is 1/2in play in the chain
Click to expand...
You should be able to just eye the chain line. You're probably aware the chain stretches unevenly. Check to see there's enough slack at the tightest point.

If your motor is brand new, sometimes the engine sprocket teeth have to wear in a little to fit the chain properly.
 
Venice Motor Bikes

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
7,272
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Los Angeles, CA.
The master link is a little larger than the other chain links & can hit the engine case (or the frame) while the bike is rolling... Check on that.

Using a 1/2 link will definately hit the case!!
 
Last edited:
J

jwmorrow

New Member
Jul 9, 2012
7
0
0
harrisburg pa
Ok i figured it out. couldent for the longest. so i took off the drive chain and went for a pedled ride. the sound was coming from the rear hub. So i took the coaster hub down and found that 4 ball berings were damaged on the left side. Almost like they were hit with a hammer and then sanded on one side. Nothing else was damaged on the hub or assembly. I thought that the ball berings were suppose to be the hardest metal in this type of assemble
 
biknut

biknut

Well-Known Member
Sep 28, 2010
6,632
411
83
Dallas
I almost mentioned the rear hub. i just fixed a noise coming out of my rear hub. The brake cones were dry. The coaster brake got real hair trigger, and it made a squaking noise. It sound like it was coming from the front of the motor.
 
Greg58

Greg58

Well-Known Member
May 1, 2011
5,353
2,575
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Newnan,Georgia
I also have had bearing noise in the rear wheel that sounded like engine problems. I think I may be focusing on the engine too much when looking for noises.
 
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