I'm not well-versed in chain and how to tell the number. I do know that the chain on the wheel sprocket does not seem to roll over the one that's between the motor and the Jack shaft. The one between the motor in the Jack shaft looks smaller and more narrow and the one that goes from the Jack shaft to the rear sprocket seems bigger and wider... the sprocket on the wheel doesn't seem very wide at all... Even though it has what seems like the bigger chain...