250r bore

[84 250R]

i bought an atc 250r the other day and the guy i bought it from had it bored out almost all the way, it still has one bore left, i was wondering if anyone knew close to what the cc might be. thanks

[methyman]

max bore on 1985-1986 bore is 69.5mm which comes to .140 over p14 piston which Wiseco is the only one that makes a piston that size. the 1984 ATC air cooled can be bored up to 72 mm which is a 262 which is 2 mm over. Stock bore is 70 mm and crank stroke is 64.4 mm.
85-86 bore is 66mm with crank stroke 72 mm with bores up to 3.5 mm over bores.

I hope this helps

Later

Matthew

250R Knutt

[84 250R]

yeah, thus is gonna help alot! thanks! i should be able to get a good estimate on the cc size now and some new jets i need to buy