Chain, sprocket or alignment issue?

[LaFuriaRoja01]

Only got my little china 66cc on this week and past one day of successful riding it's be nothing but issues with the chain. After a good ten miles, the master popped off and the 415 chain I got with it went flying everywhere. Replaced the master, and now the chain pops off the sprocket into the spokes. Every time.

Worked for a good five mile ride the other night when I put crazy high tension on it before it popped off again. Now I'll have it where it looks and acts fine, but one ride around the block later and - boom - back to square one. Between the past three days I must've put over eight hours of work into it and I'm ready to give up - was hoping somebody had any ideas.

It's a standard 44T sprocket, 415 chain, I've tried flipping the sprocket, angling the wheel, the sprocket is 100% centered with no wobble, I've tightened it to try to bring it in to the wheel a little more, I even angled the engine to try to bring it out to the left somewhat, tried varying levels of tension, no matter what I'm still having issues. Anything I should try that I've missed? I'm reading some people saying to file down the rough sprocket teeth?

Edit to include pics.. This is without tension and before angling the engine.

 

[maniac57]

The stock chain tensioner needs to be twisted to line up correctly on almost EVERY bike.
I use a huge crescent wrench to twist them till they guide the chain onto the sprocket smoothly.
DON'T try twisting it ON the bike or you risk a bent frame.

 

[2door]

What am I missing here? Are those photos flipped or what? The chain and sprocket are on the wrong side. What engine are you using?

Tom


EDIT: I just flipped one of those pictures in PhotoShop and found yours is backwards.
Anyway here is a little help with chain alignment. Maybe it will help.

 

[KCvale]

The stock chain tensioner needs to be twisted to line up correctly on almost EVERY bike.
I use a huge crescent wrench to twist them till they guide the chain onto the sprocket smoothly.
DON'T try twisting it ON the bike or you risk a bent frame.

In addition the tensioner can be mounted with big side on the inside or the outside, the object is to get your tensioner pointing straight up to the pully and as mentioned above the tensioner wheel itself is in the same line as the chain.

Note:
The ideal place for a tensioner if you can do it is where the left edge of the wheel lines up with your rim like this.

That way if it ever does comes loose it hits your rim and doesn't go into the spokes, but not easy to do with the parts provided.

Of course the best way for your own personal ride is no tensioner at all.
If you have horizontal dropouts you can make a straight tight run sprocket to sprocket and just move move the wheel back to tighten the drive chain.

That is whole different ball game however.
It usually means putting a tensioner on the pedal side chain if you can't move your engine vertically but it can be done.

You'll get it but I think the posts above are spot on, get your tensioner right if everything else is aligned right.

 

[maniac57]

In addition the tensioner can be mounted with big side on the inside or the outside, the object is to get your tensioner pointing straight up to the pully and as mentioned above the tensioner wheel itself is in the same line as the chain.

Note:
The ideal place for a tensioner if you can do it is where the left edge of the wheel lines up with your rim like this.

That way if it ever does comes loose it hits your rim and doesn't go into the spokes, but not easy to do with the parts provided.

Of course the best way for your own personal ride is no tensioner at all.
If you have horizontal dropouts you can make a straight tight run sprocket to sprocket and just move move the wheel back to tighten the drive chain.

That is whole different ball game however.
It usually means putting a tensioner on the pedal side chain if you can't move your engine vertically but it can be done.

You'll get it but I think the posts above are spot on, get your tensioner right if everything else is aligned right.

KC covered it very well.
One thing I would add is that even with a bike that has vertical dropouts, you can sometime still do away with a tensioner and simply add shims to the rear motor mount to adjust chain tension. I have done this several times with good results.
NO tensioner is BY FAR the best setup if you can make it work on your frame. It has much less friction and rides better, especially when pedaling.

 

[LaFuriaRoja01]

What am I missing here? Are those photos flipped or what? The chain and sprocket are on the wrong side. What engine are you using?

Tom


EDIT: I just flipped one of those pictures in PhotoShop and found yours is backwards.
Anyway here is a little help with chain alignment. Maybe it will help.

Sorry about that, the bicycle was upside-down in the picture, the sprocket is on the correct side, it's a standard 66/80cc China two-stroke. I took off the rear wheel today and pulled the chain straight back; it does appear that the sprocket may be too far out for the sprocket to reach. How could I possibly remedy this? I flipped the sprocket already so it is clam-shelling towards the wheel, tightened the sprocket bolts to their max and slightly angled the motor out. Is there any way I can space out the engine drive sprocket?

KC covered it very well.
One thing I would add is that even with a bike that has vertical dropouts, you can sometime still do away with a tensioner and simply add shims to the rear motor mount to adjust chain tension. I have done this several times with good results.
NO tensioner is BY FAR the best setup if you can make it work on your frame. It has much less friction and rides better, especially when pedaling.

I was actually able to achieve a no-tensioner setup very briefly; the chain is short enough to where I was able to push back the wheel enough and throw a washer or two, as you suggested, on the rear mount to tension it nicely. This worked for a nice ride around the block, but on the second motor startup - pop - chain jumped off.

Granted I can get it to work without the tensioner, I'm also hearing that swapping the chain out may help me out somewhat. I have a 415 chain and am getting recommendations for a #41 chain.

 

[maniac57]

If it still runs off with no tensioner, you have alignment problems or the sprocket is not mounted correctly.
Have you spun the wheel with a pointer on the sprocket to check runout and centering?
Checked chainline for straightness with a yardstick?
Do a search for more info. Type in "Chain alignment"