can't get right (jetting)

[trex trx400]

ok so i've searched and i've read and i've trialed & errored for about a week now so i need some help with this. gotta 07, big gun full, k&n, no choke, no airbox lid. putta dynojet kit in it started with 2 turns out 170 main 3rd clip 42 pilot. now i'm at 4th clip 160 2 1/4 turns out and i've been up and down trying to get it running good. so the idle is rough missing and backfiring, A LOT of backfiring on decel. I've checked the header bolts they're tight. still pulls hard but misses through the entire throttle and rpm range. fuel is 93 it's good. hope somebody will help thanks

josh

[Pabst_Powered]

I have a similar set up, except for the full exhaust and choke removed, also not sure where your located, I'm running a supertrapp ids2 slip-on, k&n filter, k&n power lid and the dynojet kit, running 170 main, 40 pilot (tried a 42 pilot and it barely started, when it did would idle like crap, 40 pilot fixed all that), 3rd clip on needle and 2 1/2 turns on a/f screw, it runs great and the plug reads right...4th clip seems pretty rich, and with a 42 pilot its prolly getting to much gas, try a 40 pilot, 3rd clip, and 2 1/2-3/4 turns on a/f screw, hopfully this helps, jetting can get stressful :grr:

[jcs003]

get a lectron and your problems will be solved.

[f4iracer]

go 3 turns out on your a/f screw. Also, get rid of that 42 pilot and put a 40 pilot in. It's too hard to try and tune with the a/f screw when your pilot jet is so rich!

The main jet won't affect your idle so you should first try to get your idle cold start missing and backfiring fixed! If you're missing and backfiring on startup you're too lean and you need to turn your a/f screw out.

Dynojet suggests having it at 3 or 3 1/2 turns out with the stage 1 2 and 3 kits.

[CarGuy7a]

If you are getting backfire on decel and you don't have any exhaust leaks and cannot fix the problem with pilot jetting, look into the air cut valve on the carb and make sure it's working. It's a little vacuum assembly that temporarily cuts some of the air going through the pilot circuit (creating a rich pilot condition) while decelerating to help eliminate the popping.

[honda400ex2003]

first off a 170 is too much for a dj on a stock bore no matter what the instructions say. i would start with about a 160 and shouldnt be any more than a 165. go with the 42 pilot, 2.5-3 turns out on the f/a, 3rd needle position and you should be close. if it is still popping on decel after that go to 3.5 turns out. if it doesnt clear it up you will have to go to a 45 pilot or you have a leak somewhere. give it about 5 pumps on the throttle before you start it up to help it out and make sure you start doing your testing with it warmed up good if you can keep it running long enough. good luck with the dj stuff, after my first setup with just my slip on and my filter i never got anything dialed anymore. steve

[clemsonteg]

Originally posted by f4iracer
go 3 turns out on your a/f screw. Also, get rid of that 42 pilot and put a 40 pilot in. It's too hard to try and tune with the a/f screw when your pilot jet is so rich!

The main jet won't affect your idle so you should first try to get your idle cold start missing and backfiring fixed! If you're missing and backfiring on startup you're too lean and you need to turn your a/f screw out.

Dynojet suggests having it at 3 or 3 1/2 turns out with the stage 1 2 and 3 kits.

I have a 42 pilot on my modded 400ex and a 42 on my wifes completely stock and it wasn't hard at all for me to tune them. I just installed them and screwed it in about 1/2 turn or so from where it was at already when it was running.