I'm wondering if anyone else has the same problem? I have an 04 Raptor 660R with a Big Gun Race slip-on, dyno-jet kit (set everything to specs as per the instructions) and a K&N with the billet adapter (Pro Advantage Stage 2 Kit). I get good performance but a lot of backfire when I let off the throttle. Is it normal with this kit? I'd rather run lean then rich any day as I believe that's where i'm at. Just wondering if anyone has made some minor adjustments that eliminate some of the backfire? I'm at 2,000 ft and i keep the lid on the airbox.

 

If you plan on running lean then you can plan on kissing that motor good-buy. The backfire is caused by a lean pilot circut. Try adjusting the air screw and see if it helps. If it dosn't try steping up on the pilot jet one size and see where that puts you.

 

Thanks for the feedback. Have you ever adjusted the dual carbs on the Raptor, you have to take off the gas tank just to adjust the screws? I set them three turns out like the directions, I guess I'm going to have to play with it some more. If i adjust the screws out further will I decrease the flow of gas or increase it? It's been along time since I played with carbs, but it's coming back to me. I did this kit with no problem but you forget some things over the years. Thanks, I'll wait to hear from you!

 

Your air screws should be located on the side of the carb's. Turing them out will lean it out, turning in richens them up.
I wouldn't suggest running your air screw out that far. Usually It's best to be around 1-2 turns out. At three sometimes they tend to vibrate loose and come out. Turn them in and go and see where it puts you. Try going at 1/8-1/4 turn and then try it, and keep repeating until you find somthing that works.

 

Thanks I'll try it. Dyno jet is out here in Vegas you think they would be more accesible to ask questions but there not. I thought three turns out was quite much.

 

You can never count on written instructions to be dead on. They make recommendations but there are so many factors that can change it like temp, altitude, and humidity. The best way to do it is keep doing the plug checks when ever you suspect somthing is wrong. Or if you want to get really technical you can get a EGT, either way jetting's still a pain in the azz
I've seen two bikes, both raptors with the same mods running in the same area both have different jetting combo's. [img]i/expressions/face-icon-small-shocked.gif[/img]

 

When is the fuel injection kit coming out? (An affordable one) I've heard some stories out there but no ads yet. I'll look into the tool too, I'm sure you have to mount a sensor somewhere to hook it up?

 

Yea you have to drill into your exhaust header a couple of inchs from the cylinder. I think you have to buy a block off kit, or plug or somthing so you can fill the hole when your not using the guage.
Here's some links;

Pro Flow EGT
Pro Flow EGT Block-Off

 

I dont think ya have to mess with the pilots unless you do some hi-perf internal mod. I bought a dynojet stage 2 kit, and im running 146-148, like the instructions said. Thinkin bout goin to 148, 150,, the biggest jets that came with the kit. At 2000 ft, I think id try the biggest jets that came with the kit. Bosch