What bore do I need to get a 425ex. Is it 30 over
And I can still use my factory sleeve, right???

 

no, you cannot just bore it .30 over (thirty thousandths of an in)i would say you need a new sleeve.alot of people think you can bore a bike a small amount and get big displacement.

 

no, you cannot just bore it .30 over (thirty thousandths of an in)i would say you need a new sleeve.alot of people think you can bore a bike a small amount and get big displacement.

 

no, you cannot just bore it .30 over (thirty thousandths of an in)i would say you need a new sleeve.alot of people think you can bore a bike a small amount and get big displacement.

 

Accordind to my Wiseco book...you would have to bore your cylinder over .120...they do make a piston that size and it doesn't need to be re-sleeved. That should give you about 427cc's. I would talk to an engine builder because .120 is a lot bigger for not having to re-sleeve, might cause a heat or ovaling of the sleeve problem.