Hi everyone. Need jetting advice on 07 250. 5-7 K feet. DJ 2206 kit, 300 muffler, 4 strokes header. 38 pilot. kouba screw. stock filter, no lid. Also need used 351, 340, 331, or anything else bigger than 300 piston-just to study the design. Thanks guys!

 

I'd go with a 128 DJ main jet, needle clip in the 3rd position from the top, slide drilled according to instructions, and Kouba screw out to whatever brings the best idle and off-idle response. You might want to try a 35 pilot too. Frankly I don't see a great need for jetting changes until you get up to 9000-10,000 feet on a regular basis. Note I said "regular basis". I go to the Colorado high country every year, and you really don't stay at those extreme elevations except for very short periods, usually minutes. If you have a GPS and take note of where you're riding most of time, you're more frequently around 6000-9000 feet. I live at about 1700 feet, and I never change my jetting for these trips. Our CV carbs do a great job of compensating a bit for higher elevation for these short periods.

 

Yeah, I am at 3500 feet and could not get a 38 pilot to work, even with a big bore. I had to go back to 35 stocker.

Don't be surprised if your bike surges a little bit with the big pilot in it at higher elevations.

What TNC said, thats pretty much exactly where I am at.