300ex piston question

[YZ400EX]

Ok so I have a spare 300ex cylinder with an 80mm bore/sleeve. I know it takes a 80mm piston, but what is this over stock like .20, .40, .60 etc. Just trying to figure out the specs over stock this piston is. Anyone know?

Also another question about the cylinder. I have been reading that the cases need to be machined for this to fit.. anyone know on this?? anyone know if this could be a stock cylinder bored or is the 80mm over the stock 74mm too much of a bore?? I am wondering because I dont want to have the cases machined for this to fit..Anyone have any answers on this.. Thanks in advance!

[Colby@C&DRacing]

80mm is a 330 kit which is 6mm over stock and you will have to machine the cases if it does not have a tapered sleeve.

[YZ400EX]

Originally posted by Colby@C&DRacing
80mm is a 330 kit which is 6mm over stock and you will have to machine the cases if it does not have a tapered sleeve.

6mm over stock I know, but is it like .60 .80 or is it more?? I want to know what the measurement is in thousands.. Also if the cases are to be machined, can it still be assembled when having it machine or does it just have to be cases only??

[Colby@C&DRacing]

the cases should be split and then machined 6mm is .235

[YZ400EX]

Exactly the answers I was looking for.. Thanks