I run a very similar airbox and pipe mod such as yours. Had a terrible time jetting it until I whittled down my airbox lid and put an outerwears on it(removed the snorkel also). I use a Dynojet stage two kit. The mains are dj146/dj148, dj needles are four slots up from the bottom and the fuel mixture screw is three turns out. Runs consistently good all the way through the rpm range. Maybe try a jet kit. I know alot of people bad mouth them but mine added power and weeded out the lean spots in the rpm range.

 

yeah, they are very very worthless.....oh well, me and 87banshee250sx, (or nick), are gonna split the cost of the site to make it have more bandwidth, and more space. it aint that much, so hopefully the site will have no problems.

 

Thanks guys for all the help. I tried GregV's advice and it popped and sputterd on decelleration and backfired some. The headpipe glowed BRIGHT red. I tuned the fuel screws out another 1/2 turn each, put on a prefilter, and put on an outerwears airbox cover and that fixed everything except the glowing pipes. They still glowed but not nearly as much. Should I keep tuning out the screws until the glowing goes away? Thanks!

RR1

 

How far up the pipe is it glowing?? If it's less that 6" you are fine. Once you are riding it, the air should cool it enough that they won't glow so brightly.

If it's real bad you may need to go to the 25's on the pilots. I did, but only after I went to my 686 setup.

I wouldn't go past 3-1/2 turns out on the screws. If after you do your plug read it still looks lean, go up to 152.5 / 157.5 mains and you should be golden.

You were right on the money with tuning away the popping. It sounds like you real close. [img]i/expressions/face-icon-small-smile.gif[/img]

 

Raptorracer1 i think your idle pilot jets are to lean. When i started mine up after installing a 11:1 piston and doing some of my own polish and port work, I was running 22.5 pilot jets and boy you talk about some glowing head pipes, I called Mark Robertson and he sold me some 27.5 pilot jets, problem gone. I would suggest what GregV is using in his 25 pilot jets.

 

Just incase you missed it, I updated my above post.

Keep us posted on your progress.