85-86 250r bore size

[swampthang]

What is the final bore size for the 3rd gen 85-86 250r stock sleeve? I see on ebay there is a 69.5mm top end kit. This seems huge to me. Here I thought 68mm or 2mil was the final bore.

[GO OVRIT]

On 85/86 you can go 69.50 with the pro-x piston, and 70.00mm with a yz piston. With a stock stroke that makes a 277cc.