Help with piston size

[82 250r]

Hello

I am replacing a piston in an 82 250r and cannot figure out what size it is. the skirt measures 70.256mm (2.766in) and the number on the top reads 431n07050 as far as i can read it.

Is this a .10 over?

Thanks for your help

Marc

[ColeTrickle]

Standard bore on the 82 250 r is 70.00 mm so 70.25 would be .010 over in inches. In my TR catalog Wiseco list a 70.50 oversize or .020 over. So if the cylider isn't that bad you might get away with .020 over or next is .030 over.

[Bryan Raffa]

81-84 the standard bore is 70mm thats right out of the wiseco book... 70.25mm is the first over bore,, are you shure the number is not 431m0750 on top??? that means that it is the 3rd over piston at 70.5mm

[82 250r]

thank you all. my machinist read the number to me over the phone so i could be wrong.

Sounds like if the last numbers are 50, then it would be a .020 over.

Am I correct?

Marc

[Bryan Raffa]

yes sir 0.5mm,, 2nd over