atc 250r

[Ruby Soho]

will an atc250r engine fit in a trx 250r chassis?

[deathman53]

what years, a 85/86 will fit

[wilkin250r]

All liquid-cooled 250r engines have the same external dimensions, whether ATC or TRX. The 85 ATC engines will drop right into any TRX frame.

[Ruby Soho]

whats the difference between engines? are they the same?

[wilkin250r]

I'm not sure of the exact differences. I think the pistons are the same...

[zedicus00]

85-86 are short rod engines

85-87 hav taller 5th an sixth tranny gears

porting is slightly different across all yrs

85 -86 hav a piston with a slightly lower piston pin but an 85 -86 piston will work on long rod engines with a spacer plate

jugs are interchangeable across all yrs

heads are interchangeable across all yrs but hav slightly different internal dimensions.

85 atc engines hav a lighter flywheel

88-89 hav the best ignition system

89 has the best clutch system

thas all i can think of at the moment

[zedicus00]

also, any yr engine can be made into any other yr specs with changing of apropriate parts. therefor it is possible to hav a shortrod engine with the better 88-89 gearing. or turn an 85 86 engine into a longrod ect...