250x bottem end and 300ex top end?

[NikNacs67]

Will a 300ex cylinder fit on a 250x bottom end?

[2004TRX450R]

I haven't ever done it and don't know for sure but it seems that it should. Just don't quote me on that.

[jtej]

it will fit but if you are using the 250 crank and connecting rod it will have low compression since the only difference is the length of the stroke not the actual diameter of the piston. meaning the piston will not rise as far up the cylinder wall resulting in less compression of the air trapped in the cylinder. so in short it will fit but may not run right if at all. use a 300 crank and rod and it should work

[2004TRX450R]

Well that depends. Just because it as a shorter stroke doesn't mean it will have less compression. One rod could be longer or the piston could be taller. It wouldn't supprise me if the cylender is the same on either one and just has a bigger sleve or maybe even just bored out a little. If you have both cylenders check the heigth of the cylender from the base gasket surface to the head gasket surface.

[exman]

I think the only difference is the valves in the top

[markeg192]

It should work but I think you have to use the 250 piston to match the stroke. Better check with someone though

[Smokin 440]

The bore is the same, the stroke on the 300 is longer though... i don't think there will be any difference in compression, but dont quote me on that.