I have a 1990 Trail Boss 250 2x4 that is going to need an engine rebuild. I was just wondering what is interchangeable engine wise from a later Trail Boss 325 same body style? I would like to up the power a bit and didn't know if just bolting up some parts was possible. I think the 325 were liquid cooled, would that make a difference? Just trying to get some ideas. If nothing else I will just port/polish/bore the cylinder.

Any input?

 

250 is a 2 stroke, 325 is a 4 stroke. Pretty sure the frame changed on those also.

The 325 is air cooled, but has an oil cooler that is often mistaken for a radiator.

You could swap them out, but it's not worth the time, money and fabrication work it would take.

I'd say just rebuild the 250.

 

Well that takes care of that idea. I didn't realize the 325 was a four stroke. I'll just rebuild the 250. Thanks for the input!