Vibration problem in 1st gear

Richyryder · 10-07-2011, 03:45 PM

Hi, I have a 150cc chinese-made, general-purpose street bike. It had some general vibration issues relating to the engine. I took it to the dealer and he tightened all the engine bolts. This didnt help so he replaced the drive sprocket with one that had 1 extra tooth. I dont know if he did anything else, but after that, the vibration issue was solved!

A short while later, I wanted to pop a wheelie so I put the bike into 1st gear, revved the engine, and popped the clutch. As I popped the clutch, I heard a stange noise from the engine area, and since then the bike has had a vibration issue. In 1st gear, when I accelerate at full throttle, there is a bad vibration when the revs get to about 7k (handle bars, seat, foot pegs and tank vibrate). This vibration gets weaker when the bike is in the higher gears.

I just had all the engine bolts tightened at the dealer and the problem is still present. I think it could have some thing to do with the drive sprocket. Any suggestions to help will be appreciated.

Richy

katoranger · 10-08-2011, 07:32 AM

I would check to make sure a mounting bolt has not broken first.

Richyryder · 10-08-2011, 10:40 AM

Thanks for the reply, but I just had the dealer check and tighten the engine mounting bolts.

Richyryder · 10-08-2011, 11:57 AM

I removed the sprocket cover to check the front sprocket. There is a small but noticable amount of play between it and the shaft (radial play as well as "wobble" play). The retaining bolts on the sprocket were both tight.

Weldangrind · 10-08-2011, 03:41 PM

That's by design. If the sprocket was solid mounted to the countershaft, it would probably break the chain or sprocket teeth.

clippedwings · 10-12-2011, 07:35 PM

It could be your chains slack hitting the sprocket cover. Sounds ridiculous I know but check the slack in your chain. If its been doing it long enoough you may even notice wear on the outside of the chain. I had this happen with one of my bikes where I actually had to grind away a bit of the sprocket cover for it to stop.

10-07-2011, 03:45 PM	#1
Richyryder Join Date: Oct 2011 Posts: 3	Vibration problem in 1st gear Hi, I have a 150cc chinese-made, general-purpose street bike. It had some general vibration issues relating to the engine. I took it to the dealer and he tightened all the engine bolts. This didnt help so he replaced the drive sprocket with one that had 1 extra tooth. I dont know if he did anything else, but after that, the vibration issue was solved! A short while later, I wanted to pop a wheelie so I put the bike into 1st gear, revved the engine, and popped the clutch. As I popped the clutch, I heard a stange noise from the engine area, and since then the bike has had a vibration issue. In 1st gear, when I accelerate at full throttle, there is a bad vibration when the revs get to about 7k (handle bars, seat, foot pegs and tank vibrate). This vibration gets weaker when the bike is in the higher gears. I just had all the engine bolts tightened at the dealer and the problem is still present. I think it could have some thing to do with the drive sprocket. Any suggestions to help will be appreciated. Richy
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10-08-2011, 03:41 PM	#5
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	That's by design. If the sprocket was solid mounted to the countershaft, it would probably break the chain or sprocket teeth. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
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10-08-2011, 07:32 AM	#2
katoranger Join Date: May 2007 Location: Altamont, Kansas Posts: 15,103	I would check to make sure a mounting bolt has not broken first.
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10-08-2011, 10:40 AM	#3
Richyryder Join Date: Oct 2011 Posts: 3	Thanks for the reply, but I just had the dealer check and tighten the engine mounting bolts.
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10-08-2011, 11:57 AM	#4
Richyryder Join Date: Oct 2011 Posts: 3	I removed the sprocket cover to check the front sprocket. There is a small but noticable amount of play between it and the shaft (radial play as well as "wobble" play). The retaining bolts on the sprocket were both tight.
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10-12-2011, 07:35 PM	#6
clippedwings Join Date: Aug 2011 Posts: 14	It could be your chains slack hitting the sprocket cover. Sounds ridiculous I know but check the slack in your chain. If its been doing it long enoough you may even notice wear on the outside of the chain. I had this happen with one of my bikes where I actually had to grind away a bit of the sprocket cover for it to stop.
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