Having Gorr perform a 265 o/b on my 03 KX 250

[scotthenry]

Eric Gorr is in the process of doing a 2 mm overbore on my 03 KX 250. Any suggestions on what to expect power wise and jetting wise. I live in KC run B32 mixed with maxima 927 at 32 to 1. Running a 160 main a 50 pilot and a nafg needle. Air screw 1.5 out. Pc pipe and and shorty silencer. All this is pre 265. Have not got the motor back yet but am anxiously waiting. Doing the 265 with Mo mid and top porting. Any suggestions??? Any experiences???? Good or bad.

 

[MXTex]

Eric did a 2mm over on my 98KX250 with more better everywhere. Awesome motor. Very linear with no hit. I'm running a 155 main jet and have raised the needle clip one position. This is leaner that what the stock bore required. I run pump gas with premix @ 32 to 1. Good luck and enjoy your motor. To do it over again, I would get the porting option you have opted for. Great choice!

 

[Lorin]

I have the 265 on my 98 yz, and ended up going a little leaner after the "all-around" porting and overbore. I am running a 42 pilot, and a 168 main now (was running one step richer on bother circuits previous to the kit). I am in Oklahoma, so my jetting conditions should be similar to yours. I am running Mobil mx2t @ 40:1.