yz 265 won't run at the top

Hey, this is my first post, so here it goes.

I have a 95 yz 250 with what i believe to be a 265cc stroker kit ( at least that's what the previous owner said, and there is a 4mm spacer plate under the jug), pro circuit pipe/silencer, and boysen rad valve, I am currently running 98 octane pump gas @ 30:1 I tested the compression and got around 170psi after 5 kicks. carb is the stock PWK 38mm pilot jet is also stock @ 48 with the stock R136 needle on the 3rd clip

the problem is that the bike will not run at WOT in a high gear, it will start to wind up, then begin to miss and the front-end will dive. The bike seems to run fine through the rest of the powerband though. i have tried main jets from the stock 175 all the way to 220, but am currently running a 195. I haven't changed from the stock R136 needle; I have moved the clip around a bit, but to no avail.

I just really don't think that my buddy's 250f should feel like it's just as fast as my 265.

ANY Ideas would be much appreciated ( especially with the jetting it feels lean but I'm not really sure.

thanks

the reeds have 3 rides on them, but i will check the powervalve

thanks