KDXRIDER.NET

So I've got a 200 motor in pieces in a box and a 1997 CR250 roller. I nee to gain 2 mm at the rear/swingarm mount pass through. Is there a reason to not remove the material from the engine cases? The reason I'd go this route is I have a 1997 CR250r, and I'd like to keep as many parts as possible interchangeable.

Look at what is involved in putting the 200 in a Kx frame as I believe when that is done, the back engine/swingarm mount is reamed out a couple of mm. Plenty of these hybrids have been done so it can't be that bad of an idea making that hole bigger.

I think you would be ok with taking 2mm off of the side of case. I have a motor apart right now, here's what the inside looks like (same on the other case half):

Thanks thats helpful. Just picked up the CR roller on Sat have had the KDX in a box since Sept. I have used Eric Gorr exclusively for my 2 strokes since the 1980s, was going to have him turn the jug into a 220 and have him do the cases at the same time. ... Opinions?

Did you mean 223 cc instead of the stock 216 cc on a KDX220R?

No it's a 200 currently

Well, Eric Gorr can do a 223 cc version (or he used to)

Doesn't sound like a bad idea to me. You'll have to sent the power valves out too to be machined down to accommodate for opening the bore. If you can find a complete 220 cylinder, might be cheaper. I know Eric Gorr does some darn god work though.

Wish I could weld aluminum so I could have done an aluminum frame hybrid! lol good luck, be sure to post up your progress once you get into it.

I had E.G. do the 225 kit on my 200 cylinder. I opted for the mo better porting (think that's what he called it). This smoothed out the hit and increased the low to mid significantly. I did some other mods at the same time and I really like the result. Low and mid are awesome and the top is good, but I could use a little more......who couldn't? Good luck with the build.

I also have the 223cc kit with 'mo betta' porting. The Wiseco piston has a different compression height than stock and the 223 motor only had 135 psi when it was new (compression readings taken with a calibrated compression tester). The motor runs great with a really good midrange - but it could be better with more compression. Yes, punch the motor out to 223 - you will not be disappointed. Also, know that there is more potential locked up in the motor that I'm going to go looking for some day. My motor is running a squish of 0.058 (with a Ron Black modified head) and I'm going to machine the top of the cylinder to set the squish at 0.040". The 223 kit has 90 hours on it and I'll be taking it down this spring for a new piston - at this time I'll machine the top of the cylinder. BTW, my Rekluse installation now has 149 hours.