I need a new rear sprocket. It's not available. I emailed JT sprocket and they said too bad...cant help. Don't make those. So I did some research. It seems the 81 yz80j has the same hub dimensions (62mm) and the bolt holes from center to center acrossed seem right( 80mm). Not sure about spacing between them. It is a 428 chain application instead of the yz60's 420. If I buy a 12t 428 front sprocket and the JTR 1842.44 sprocket for the 80cc.. . Will it work if I get the appropriate 428 chain? Surely someone doing a yz60 needed a sprocket....ebay is overpriced crap no better then mine. Mine is shot.