plug fouling with new pipe on 400ex:confused:

[400exJOE]

I have a 2001 400ex and bought a K&N filter, prefilter, dynojet kit, and Supertrapp IDS2 silencer. I removed the air box lid and am running a 170 jet. The dynojet kit said this would be right with "a good exhaust system." The quad is running too rich though. It fouled the plug and wouldn't start for anything. I replaced to plug and it runs fine but its still rich a little. Dynojet says to turn the fuel mixture clockwise screw until it sets, and then back it out 3.5 turns. Which way turning the screw makes it more lean? Clockwise or counterclockwise? Will that solve my problem, or should I decrease in jet size? If so, how much? The next smaller size is a 165 included in the set. Will that be too big a gap? Thanks

P.S. sorry for making that so long!

[TRX_Thumper]

If its that rich the mixture screw won't help stick the 165 main in it.

[Adams44]

I would go with 158 or 160. Since you didn't mentio other mooto mods. That is the problem with that dyno jet kit, the jets they send are TOO BIG. Call any motor builder and they will tell you with your mods, 155 - 160.

Also, did you still have the stock needle in. I would put it back in and run it on original setting, you may have to raise the needle, but I still would start with stock. Stock Pilot also.

The 400ex comes just a hair on the rich side anyway.

I am currently running 42 pilot, stock needle up one clip, and a 160 main with motor mods - Sparks full exhaust, lightened flywheel, TC cam (XC), 11:5 to 1 compression (426 cc), K&N, modified airbox lid. I feel it is still a little rich on pilot circuit.

I won't say what I feel about the "power up" kit....yea...I bought one also...since then, the only thing I used was the filter and pre-filter, the dyno jets went into the trash can along with that cheap adapter. I buy kehein jets now.

Good luck
Nick
GNCC 426EX

[dad400ex]

I agree, throw away that power up kit,all that does is turn your good Keihn jet into a junk mikuni jet.Go out and buy all the 160 jets and start at the lowest one and keep going up until it coughs alittle then back down one and that should be the one.....

[KAWSAM62]

A 40 PILOT WITH CHOKE LEFT IN AND A MINIMUM 160 MAIN STARTING POINT AND WORK UP:cool:

[dariusld]

I have that jet kit, with the mods in my signature, and ran the 170 with no problems. It might be on the rich side,but no problems. I don't think they are junk, but it is CHEAPER to just buy the stock bigger jets. So on the second bike that is what I did.

[dad400ex]

A big differance is where you are from,so be sure to go by members that are the closest to you,tuning tips from like Fla. will not neccessarily work in N.Y ,The climate has alot to do with adjustments.