250r questions

What are the differences in 250r motors throughout the years, including the trx? Are they interchangeable, what parts of them are? Were any year's better than the rest? Do they make more aftermarket parts for any certain years? You can bolt a TRX motor in an ATC, correct? I know it's alot of questions, but I'd like to build up an ATC and want to know what year parts to look for. Thanks for any help!!

[Instinctz]

From the year 84 and down the engines are air cooled. From 85 and 86 the engines are water cooled. 86 Engines will directly interchange into a trx frame I think.

The atc and trx share alot of features.

[OldSchoolin86]

All the R motors from 85-89 will interchange.

Thanks alot for the info! In the 85-89 water colled engines, are the internal, jugs, heads pistons, etc. interchangeable?

[OldSchoolin86]

The cranks and pistons are different on the 85-87 motors from the 88-89 motors. Other than that everything should interchange. They all have the same bore and stroke. You can inchange the crank and pistons but they have to match years. So if you use a 85-87 piston you need the 85-87 crank. You can even mismatch them with the right adapters.

[atc86r]

if you buy one buy the 86 atc r . the swing arm and stuff on the back are interchangable with trx's. the 85's have unique parts for 85 only. i was reading a magazine and 270r that won desert race has 85 bottom end on it.

[Cahdealme]

I am working a deal on an 86 250r and 2 water cooled engines. The seller thinks one of the motors is the original off the bike, not sure about the other one. One motor has a bad case, the other a bad stator. I'm hoping to build both motors, but might have to settle with combining them to make one. All of the info has been helpful, and if any one else thinks of any more let me know.

[Cahdealme]

Are their any more frame differences between the 84 and below, 85, and 86? Are all of the plastics interchangeable? Thanks again.

[Cahdealme]

Are the axles and hubs interchangeable betwwen the years, what bolt pattern are the rims? I know it's alot of questions, but I want to know everything I can before I get any money into parts I can't use!!

[atc86r]

the 85 and 86 frames are interchangable. 83 and 84. looks like 3 different groups. 81-82,83-84, 85-86. the 86 and 85 just had that swingarm thing. parts from diff groups probably won't work but can't say for the 81 and 2 since i've never dealt with em.

[Cahdealme]

The rear rims are 4/110, correct? Does anyone know the front bolt pattern?