Re: replacement parts
There are two ways you need to true your sprocket. I check mine by removing the motor chain so the rear tire can freewheel then brace a pencil against the chain stay and almost touch the sprocket as the wheel is spinning. You can see how much the sprocket wiggles and it will brush against the pencil on the high spots so you know where you need to bring it in with the sprocket bolts. It is hard to get it perfect but keep it under a mm.
As far as being on center, you can check the same way by tracing a line around the outside of the sprocket while the wheel is turning as close to the teeth as possible then if it is off you can easily see where you need to hog it out. You can draw an sixteenth inch line on the side of the center that needs to be moved then grind away with a dremel. I would not mess with it unless the deviation is unmistakeable.
Last edited by mralaska; 09-09-2008 at 09:45 PM.