Re: I just put on my new 56 tooth sprocket and the chain keeps falling off even tho i
No the chain is not to tight or to loose. that's not the problem.
The sprocket does wobble a bit, how do I fix that?.
If the sprocket is wobbling then that's your problem. Fix it!!! You don't need to spend any money, just some time and patients.
Which way is it wobbling? Up down or side to side. Either way you need to start by slightly loosening all of the bolts holding the sprocket to the hub. It really helps to have the rear wheel suspended off the floor and the chain off so it can spin freely. Spin the wheel and determine what the sprocket is doing. If it wobbles side to side then take a close look at it and make sure it isn't bent. If you're unsure about this then completely remove the sprocket and lay it on a known flat surface. A piece of glass is about as flat as you can get but anything that you know that lays flat, a small sheet of dry wall (sheetrock) laying on a flat surface will suffice. If the sprocket isn't bent (warped) then you're good. If it is you can probably get it flat with help from a rubber mallet, large crescent wrench or any tool you can find to assist in making sure the sprocket is as flat and true as possible. Also, if it is bent then send it back to wherever you got it and demand a replacement.
Now, with a flat (no warps or bends) sprocket, reinstall it back on the wheel leaving the bolts snug but not tight. Spin the wheel. What needs to be done to make it spin true? If it wobbles side to side then start tightening the bolts, alternating from side to side in a star pattern all the while spinning the wheel to see if you are tightening the bolts uniformly. Keep tightening using the one-side-then-the-other method until all bolts are tight. I like to use a cordless drill with an adjustable clutch that you can incrementally increase the torque value as you go. I like to use a magic marker, Sharpie, any kind of marker that you can hold firmly and 'mark' the sprocket as it spins. The marks made will tell you which way the sprocket needs to go to be true. Finally I like to see something in the neighborhood of 50 inch pounds on the bolts, if you have a torque wrench. If not, rent or borrow one. Just don't wrench on them so much that you twist them off. They are only 6mm and not hardened bolts. They're not semi truck lug nuts.
If the sprocket is spinning flat (true) but has an up and down motion to it that tells me it isn't centered on the rear hub. It isn't rocket science...center it. You can use a rubber mallet or a hammer with a small block of wood between the hammer and the teeth of the sprocket to pound (work) the sprocket into concentricity with the rear hub.
Think of it this way...any wobble, side to side or up and down will add to your chain problems.
Chain tension: You said yours is good but you didn't indicate how tight/loose it is. We recommend that you have 1/2" to 3/4" slack in the top chain run when you push the bike forward, clutch engaged. Any more or less is not good.
It has already been said, but check your chain path from the engine drive sprocket to the rear wheel (driven) sprocket. Any misalignment will cause problems. Move what needs to be moved to assure the chain travels in a straight line its full length. Get back to us if these suggestions don't solve your problem.
Tom