Ok, I've got the DMC Alien, Pro-Flow K&N, and Dynojet Kit. I started with the dynojet kit and their recommendations. I am running the 146/148's and everything is perfect except for the backfire on decceleration. I started with the 3 turns out on the fuel mixture and then I tried a set of 25 pilots, its a little bit better but not fixed. Any suggestions?

 

I usualy go to 3 1/2 turns out before I up the pilot, then I'll up the pilot start back at 2 1/2 turns and try coming up untill I reach 3 1/2 turns again.
If you go this far you have a problem.
Check your exhaust from the header back.
Try dropping your pilot and then drop your c-clip down one and try again.
If you go to far on the air/fuel mixture or pilot, idle adj become a night mare

 

check for exhaust leaks use hi temp silcone on the joints and gaskets. black stuff the best. on decceleration with backfiring problems usally means rich conditions unburned fuel in the exhaust your hearing

 

backfire usually indicates a lean condition, this could be due to a leak in either intake or exhaust system, or it could be a jetting issue. you can check air/fuel mix by how your bike returns to idle after blipping the throttle it should come right back to idle, if it is slow--->lean, if it comes back fast but feels like it might die you are rich. you can try giving it a bit of choke under load and see what happens, if you have holes in your airbox try taping them up and see if the problem goes away. hope some of this helps

 

2001 raptor,
I have gytr muffler and airbox mod's, k & N filter.
I had bad hesitation on mid and top end.
I also Lost tremendous power throughout.
I also had the issue of Backfire on deceleration.
After spending $350+ to get more power and have issues like that I was sickened.

Everyone recommended the Jet kit. So I got one from the local dealer.
Followed directions.

It eliminated the hesitation on mid range. But I still had issues with the High end
hesitation. and the power was still less than stock, but it was a slight improvement. I played with pilots, Mains. tried everything people recomended. Could not get it dialed it.

I had my Carbs torn apart again Saturday to play with the needle settings, and try something, hopefully maybe I'll luck out. Thanksgiving weekend, I'm stuck at home!!
A neighbor came over and introduced himself. He's a motocross racer at the local track for Kawasaki, Sunday He showed up once more and Handed me a beer and a few jets. And we tore into the machine As his wife talked with my Gf.

He Removed the jet kit from k&n. packaged it and handed it to me, Hope I got the reciept! He said that the jet kit works fine 95% of the time. He also said the milling specs can vary slightly per jet. I may have gotten a bad batch.
He's seen it a few times before, But K & N won't admit that.
But he recommended that we try his method. It worked on a diff raptor at the track. What do I got to lose.

He swapped the stock 145/140 to 150/145, utilizing the existing 145 jet.
he then upped the pilot to a 25 from the stock 20. 2 1/4 turns out.
We also found exhaust leaks. We also found a slice in the rubber boot from the clamp. (( could of caused the problem by itself ))
Replaced the clamps and the torn boot. shifted the carbs and Airbox slightly closer to the engine for a better fit. We then went back thru the Airbox and smoothed and filed and abrupt edges.

We used all yamaha parts.
2nd notch on needle.
4.99 per pilot, 2 neccisary, 5.99 for one 150 Main. 18 dollars in jets.
2 1/2 hours later,

Eyes WIDE!
For the first time ever I was able pull wheelie in 2nd, 3rd and 4th gear.

I still have the backfire once and awhile, Lots better than before. We still can't figure that out yet.

Alot of factors could of been involved with my problem, But, This is what was done to correct it. Hopefully it'll help somebody or give direction on things to try.