265r

[fmfracing5]

how much do you have to bore a stock 250r engine to get it to 265?

[KYmxracer52]

I'm pretty sure it is .080" over.

[Eddiesanders250]

its a 68.5mm bore so 4.5mm over. convert that to inches. im too lazy

[pimpt250r]

40over is 1 mm so i am pretty sure you need to resleeve to get a 265 out of it--- 80 over is only 248 cc i think if i am wrong pls correct me

[Eddiesanders250]

your wrong


On an 87-89 sleeve you can go .80 over which is a 261cc. On an 86 sleeve you can go to 69.5mm bore. which is .140 over 273cc

[lee37vernon]

my 89 is at 68.25 mm 263 cc . pro x make even bigger pistons than this also so 265cc you can go to easy . look at mcdizzys article on making a mad 265 . not sure but think that IS the last bore then though ..

[zedicus00]

85 - 89 jugs can all go .140 over, thing is they dont make pistons that big for long rod guys, so you have to use an 86 piston and spacer plate to go over .80 on long rod setups with stock jug.

[rockman]

Originally posted by zedicus00
85 - 89 jugs can all go .140 over, thing is they dont make pistons that big for long rod guys, so you have to use an 86 piston and spacer plate to go over .80 on long rod setups with stock jug.

this is the setup i have

[C-LEIGH RACING]

A 68.00mm piston & 72mm stroke will be 261481.65ccs

A 68.50mm piston on a 72mm stroke will be 265341.1 ccs just a tad over but you can probable get by with it.

A 67.50mm piston & a 74mm stroker crank will be 264807.42ccs thats as close as you can get to a full 265 & not be over.

Open class starts at 266ccs, so if your under that it should be ok.
Neil