250-500cc JETTING PROBLEMS 11'wr250 w/ keihin pwk38

I'm having some seriously frustrating jetting issues..I'm not a pro at this stuff at all but I'm very patient and mechanically inclined so I thought I'd figured it out on my own but I need some help from some knowledgable people. I have a 2011 Husqvarna wr250 with a CR Ignition, fmf gnarly expansion camber & fmf power core 2 silencer, keihin PWK38 carb with 170 main 45 pilot, JD red needle clip 2nd from top, air screw 1-1/4 turns out,#7 slide float height 16mm and I'm running 50/50 cam2 110octane and 93 Sunoco ultra pump and I'm at sea level.. The problems I'm having is my bike is acting lean I was lacking power off the bottom and every time I would chop the throttle going into a coner my rpms would hang up and go "ding da ding da ding" so I figured my pilot was lean being a 40.. So put a 42 in air screw 1 turn out.. Did absolutely nothing. So now I have put a 45 in and it also has done nothing my rpms are still hanging up when I let off. So I figured I'll just richen everything up and see what happens I put a 172 main in lowered my clip to mid and let her warm up took it for a ride crackeling like hell up top cause she was obviously to fat.. So now I'm totally stumped.. My bike wasn't lean before I put a pipe on it, she's was ,totally perfect spark plug was golden brown, it was real snappy down low then she'd pull d like a freight train and never stop revving in the middle of the summer in south jersey. For some reason I feel like I must be missing something cause I wouldn't think that I would have to jump more than 2 sizes on a pilot jet especially with the weather cooling down to the 50's now.. I don't get it.. She was totally perfect before

Check for vacuum leak around the reed block. Honda paper gaskets can be used to correct leaks on the mating surface. Also check ignition side crank seal for sucking air. Spraying some carb spray cleaner around these surfaces while the bike is running will help you find a leak. If the engine changes then you have a leak.

Also it's possible that the pilot circuit has some debris in it and therefor changing the pilot jet essentially does nothing. You can remove the carb, disassemble it and spray cleaner through all the passage ways and while you're there make sure the choke circuit is functioning correctly and all the "O" rings are not flattened out and sucking air.

You could put everything back to standard just to make sure you can still get it to run properly, that would eliminate any air leaks from stuff thats been disturbed.

I've found this ducument very useful in the past

http://www.duncanracing.com/TechCenter/KeihinCarbJetting.pdf

I've got the same bike with full FMF, but it was all on when I bought the bike. I do richen/lean for summer/winter which I've never had to do on other bikes I've owned. The WR does seem a bit fussy on jetting.

Yes for some reason you have a lean condition on idle which explains the rough idle on throttle chop. As doug said check the reed block sealing surface or just buy the Honda gaskets. Having to increase pilot by two steps just because of pipe change seems extreme but you did say temps are in 50s now so that's a big change from summer in the 80s/90s. I suppose you could try 47.5 or 50 PJ to rule that out.

Here's a good thread on leak down testing if the reed valve gaskets don't help. http://www.thumpertalk.com/topic/432226-pressure-testing-a-2-stroke/

Thanks for the advice, I'm going to get all of the leak down stuff from the hardware store tomorrow, I'm pretty sure I don't have a air leak because I have tried spraying everything with carb cleaner while it was running it never jumped rpms.. And I'll probably go back to the motorcycle shop and buy a few larger pilots and see what happens. I just can't believe im that lean on the bottom and fine up top

I live in Toms River and have an 09 WR250 with Keihin, don't know the size (on bike when I bought it). The jetting actually worked since April here, ride in Pa in June, here all summer than today at Reading dual sport. I had various issues that I thought were the carb anc cleaned it a few times. Once I had a spec of dirt in the pilot jet.

Main jet 175

Pilot jet 42

Slide 7

Jd Needle with red top

Clip in the 2nd from top slot