Originally Posted by ran49

After a great bit of fiddling on my out of the box Boygofast kit sprocket to get it to mesh properly with the chain,I thought it might be prudent to get a proper unfiddled with sprocket,even though I had it working great.Heck,I don't feel right if I go more than a week without throwing some amount of money at my bike.
And so I did.Well I could see straight out the keyway on the new sprocket was way to small.Removed the key and after careful measuring and yet more fiddling got a good fit to key.I go to install it only to discover the sprocket bore is about.01 undersized.