maybe dumb ? but here goes

[the glassman]

are the trx 250r motors different from a cr 250:huh

[CorvetteZ06]

yes. :cool:

[GPracer2500]

Some of the differences include:

CR250R: Nikasil bore, powervalve, 5 speed, kicker goes counterclockwise

TRX250R: iron sleeve bore, counterbalancer, 6 speed, kicker goes clockwise

[atvmxr]

I thought the ~ 84 85 86 ish CR's had the same motor? The piston applications list CR's and I though the jug would bolt on...
the exhaust mounting is different though

[GPracer2500]

Originally posted by atvmxr
I thought the ~ 84 85 86 ish CR's had the same motor? The piston applications list CR's and I though the jug would bolt on...
the exhaust mounting is different though

Definitely not the same engine. 84, 85, and 86 CR cylinders are actually all different from one another. 84 and 85 cylinders had different versions of a sub-exhaust chamber device. The 86 was the first year for a an actual "valve" that changed port timing. 86 was also the first year for Nikasil.

I don't know if any of those jugs would bolt to 250r cases or not. If they would, the "PV" mechanisms wouldn't work because the 250r cases lack the govener that controls them.

[atvmxr]

I know Ive seen where people have use some year CR jug bolted up to a TRX. The exhaust flange has different bolt pattern, so the the tricky part is getting that piece to work with the TRX exhaust pipe.

according to wiseco the 84-85 CR pistons and the 85-86 ATC/TRX pistons are the same, 526M series. both have stock bore at 66 mm........

but the jug and piston are only a small piece of the puzzle, overall I agree with you that the CR motors are different