how big can you bore the 250 jugs

[dirk_411]

Hey guys just wondering how big you can bore the kx250 jugs before you interfere with the power valves or have to significantly modify them.  This question is specifically for the 98-99 jug

[KevinTwoStk]

Eric Gorr offers both 265cc and 295cc big bore kits for the KX 250, so there's no doubt you can go a lot bigger if you want to. Those kits may or may not require power valve mods. If you're wondering about an oversized piston for a near-stock bore and not a big bore kit then I'm not sure what the answer is.

I would think the mod required, if any, would pertain to the center flapper valve and not to the drum valves on the sides.

Anyone else?

[dirk_411]

I hear what your saying.  Im thinking in the back of my mind a 301, 310 or maybe a 330.  Interested what guys know in the kxriders universe

[Foxx4Beaver]

Todd has up to 305cc listed...if you contact him, he might be able/willing to go bigger.
 
http://www.kxriders.com/forums/index.php/topic,10029.0.html 

[sandblaster]

If nothing else, Todd at  Pinsonnault will tell you what it's worth based on what your application is.
Whatever you do, don't ask Motorrad what he thinks of Gorrs work.

[Foxx4Beaver]

Whatever you do, don't ask Motorrad what he thinks of Gorrs work.

ha...I wasn't gonna say it....glad you did ....not that his thoughts about him are in several threads on here.

[dirk_411]

I wont be dealing with eric gore.  What I read and there was lots of it.  50/50 good and bad. I called to talk to him and he was a total dick.

[TJXK]

Before I asked on here about what to do with my RM I had called Gorr about ten times over the course of a few days.  No one ever answered the phone.

[KevinTwoStk]

Bummer about Gorr. I've learned quite a bit from a book of his. I have never spoken with him, so I can't personally attest to his telephone manners.

[motopunk]

i ride a big bored ´96-engine with now 353,8ccm.. 78mm bore and 74 stroke with a special mashined lower crank pin .mashined suzuki rm370-piston, handmade head-gasket , i threw out the main-valve, closed the empty place and it has a special designed kx360-pipe made by van hasselt in belgium ... the engine is now in my ´87-racebike for the evo-cup ...

http://der-motopunk.de.tl/projekt-evo_racer-kx250E1-1987.htm

[dirk_411]

i ride a big bored ´96-engine with now 353,8ccm.. 78mm bore and 74 stroke with a special mashined lower crank pin .mashined suzuki rm370-piston, handmade head-gasket , i threw out the main-valve, closed the empty place and it has a special designed kx360-pipe made by van hasselt in belgium ... the engine is now in my ´87-racebike for the evo-cup ...

http://der-motopunk.de.tl/projekt-evo_racer-kx250E1-1987.htm

Way to big for me

[motopunk]

 ... its the absolut maximum that you can get out of the kx 250...

in 2000 i had a gasgas ec 300. not really more hp like the 250, but lot more torque. this engine has bore 72mm and stroke 72mm and this could be done with any actual 250-engine that has 72mm stroke .
 easiest way : buy a ktm sx250, buy the ktm-exc300-cylinder , head and piston. install it and the sx300 is ready...