chain coming off

GoldenMotor.com

archertiger3

New Member
Aug 28, 2011
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0
0
Kansas
I just finished my gas bike today, and whenever I let off the clutch (when starting the bike) about every other time the chain comes off. What is causing this?

I was thinking about a automatic chain tensioner, what is the best tensioner for a cruiser style bike?
 

The_Aleman

Active Member
Jul 31, 2008
2,653
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38
el People's Republik de Kalifornistan
Usually that's chain misalignment, from my experience. But ofc, if you have too much slack in the chain, it can happen, too.

The stock "chain tensioner" is not really a tensioner at all. It's an idler. I used it for almost 4 years on 3 different bikes and didn't have any problems with it, because I left some slack in the chain, but not enough to get thrown if I was leaning and hit a bump during deceleration or some other event likely to throw a chain. If you do a little research here, you can find plenty of options for a real tensioner. If you think laterally, you might even come up with your own tensioner.
 

archertiger3

New Member
Aug 28, 2011
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Kansas
It's only when you start the bike, I ran it for 30 minutes it doesn't come off. the chain is straight. and no wobble in the sprocket
 

2door

Moderator
Staff member
Sep 15, 2008
16,302
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Littleton, Colorado
Tension = 1/2 to 3/4" of slack measured on the top chain run with tension on the bottom.
Check your chain path again and make sure that there is a straight line from the engine drive sprocket to the rear, driven, sprocket. Also double check the rear sprocket for wobble and concentricity. If it is not precisely centered on the rear hub or there is any wobble, side to side, that's why the chain comes off. A correctly aligned and tensioned chain will run for miles and miles without a problem.

The tensioner wheel needs to be aligned with the chain path as well. Every one I've ever encountered needed to be 'twisted' to get the wheel to align with the chain. It's not just a tension adjustement device but also a guide to assure the chain enteres the rear sprocket correctly.
Sight down the chain from the rear of your bike looking forward and you might see that the tensioner wheel is pulling the chain off to one side or the other. Correct that and you shouldn't have any more problems. You can clamp the tensioner bracket in a vice and give it the required twist with a large Crescent wrench or any appropriate tool, then reinstall it to check for alignment. You'll also want to make sure the bracket can not loosen and rotate on the chain stay which will allow it to run into the rear spokes. That's a situation you want to avoid at all costs.

Tom
 

vincent713

New Member
Jun 2, 2010
287
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Dallas
On my mountain bike, I have aligned the chain perfectly without the tensioner and there are only about 1/2 inch slack. It seems to run fine right now, is this dangerous and necessary to have a tensioner? Or can I go without using one?
 

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
As long as you have no chain interference with the frame, rear tire or anything else and can keep your chain tensioned correctly, you're good to go. The chain tensioner is not an essential part unless you have issues like those mentioned.
Ride careful, have fun.
Tom
 

PerryP180

New Member
Jun 24, 2011
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Atlanta, GA
When starting the bike you need to release the clutch all at once. This is known as popping the clutch. One more thing you might look into on the chain. The stock chains are very unforgiving in any misalignment of the sprocket. Switch to a #41 chain for more strength and it is very forgiving on misalignment. I've only had one chain problem since switching and it was due to an idiot installer(me) not doing the job all the way,
 

zachary

New Member
Sep 16, 2011
43
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0
minnesota
it also could be the motor is not mounted solid to the fraim and when you pop the clutch the motor gets pulled to the left and runs the chain off of the sproket.