300cc kit in a 250cc xc-w?

after this race season i am gonna replace the top end and while i am at it i am considering puttin a 300 kit into my 2006 ktm 250 xc-w (2 stroke)

just wondering how much something like this would cost and wat brands are the best.

KTM makes a pretty good 250-to-300 kit. They call it "300 parts on a 250".

I hear you can simply swap the 300 cylinder and piston over, but if the stroke is different, I think that would mess with either the compression or port timing, or both and you would need to change the crank too. No personal experience though.

ya you can just bolt up the stock 300 parts, you need the cylinder, head, piston, and some power valve parts, gaskets etc, I believe KTM has just added a kit ( I think it comes with a black box too, but its not really necessary) to the hard parts catalogue, one is enduro one is SX, I think the head it the only difference.

Mike

One of the dirt mags just commented about one that they rode in a custom offroad bike test and said it was the best 300 they ever rode. different stroke made it a better 300...

Joe

I think it was a 250sx with a 300 top end-converted to offroad. I also plan on putting the 300 cylinder on my 07 250sx. I was riding my crf450 and miss the bottom end pull. The torque and overall power is nice with a 300. My goal is going to be a broad powerband-with traction in mind. I am going to sell my beloved 08 200xc. I got on it today and after ridiing the 450 and the 250-I simply can't ride the 200 to its full potential. Guess I am getting old.

I just converted my 07 250xcw over to a 300 and it cost 1100.00 by the time I was done and that was with me doing all the labor. I would have been better off to sell my 250 and just buy a 300. I did use all KTM OEM parts.

the KTM 250 and 300 use the same 72mm stroke, the 300 is simply a big bore kit.

One of the dirt mags just commented about one that they rode in a custom offroad bike test and said it was the best 300 they ever rode. different stroke made it a better 300...

Joe

the 250 and 300 share the same stroke, have since 2004

Mike

I have a 300cc 250SX. Also porting and head work from Munn and Dick's carb mods. I love that bike. Smooth awesome power from the bottom till it hits the rev limiter. Still not 450 fast but quite close I'd say.

I also rode the 2009 250XC w/ the 300 cylinder that won the Dirt Rider shootout as that is my local dealer and I'm friends w/ those guys. It definitely didn't have the pep of mine but of course it was set up for Hare Scramble and so it had the auto-clutch and some other stuff that made it less responsive than mine. Very nice bike however.

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