Jetting problems...

[Entomber]

I bought a used 400 with a a K&N Jet Kit, Air filter and Pro-circuit exhaust. It backfires and pops when I decellerate. I moved the needle two notches down, it still popped but much less. However it had a nasty bog and there was a lot of black smoke coming from the exhaust. At 1/4 throttle it would break up. SO I put it back to the way it was and it's much more responsive, but I'm sure it's running lean.

SO I'm going to buy the blasted K & N jet kit... like an idiot, I didn't check the jets that are in there. What size would anyone recommend and what should I use in conjunction witht the Pro-Curcuit coupled with the air-filter. Thanks for anyone willing to throw their two cents.

[Entomber]

BTW Where can I get the best deal on a K & N Jet kit. I paid 60 bucks for my kit for the DS 650. I'm assuming I can get it cheaper than that.

[rdmex]

put a 152 jet in there and see if that does anything. i have a 400ex and i have a kn filter and a fmf silencer and a 152 jet and it runs awesome

[Wheelie]

Try a #40 pilot, and if your using Keihin jets, 152 or 155 main.