Please help "Jets"

[kolby2004]

My sig pretty much sums up all my mods. I bought my 400ex about one year ago and never opened the carb untill now to do a quick cleaning and found out that my jets are 45 pilot jet and 155 main. I am having some issues. I notice the problem the most when doing a wheelie in 1st gear and once I get the front end up and just blip the throttle it seems to just cut out and the front goes back down. Or anytime I let off the throttle and then get back on it real fast it seems to cut out. I am guessing the pilot jet is too big. What should I go down to? I have a 42. Should I try that one? It seems to run good other than that. 155 seems small on the main but seems to run good. should i try anything different on the main too? Thanks

[boosted3g]

Assuming your talking about the quad in your sig the pilot should be about right but your main is too small. Tray at least a k170 or possibly larger. Your best bet is too order from a k160 to k190 and play around with it. Start big and go smaller. I ran with a k155 with just an HMF slip on and it ran perfect and you have much more motor work than that. On my set up with 11.1 piston, hotcams stage 1 and the HMF a k170 main, 42 pilot with .040 shim works perfect.

[kolby2004]

Any Other suggestions?

[AJG400]

i would put in a 42 pilot and a 165 or 170 with the pilot screw 2 turns out and see what that does for you

[kolby2004]

Alright well well I do have some jets. I have a 42 Pilot that I could try. I also have these main jets: 152,155,158,160,162,165,170,175,180 . So what should I start with? I know that I need to start high. But what do I look for? Do I need to get a bunch of plugs so I can do plug chops? I have an NGK R plug in and they r 4.50 a piece.

[boosted3g]

I would try the 42 pilot and the k170 main. Id move the needle up 1 notch or shim it depending on what year carb you have.

[kolby2004]

My ex is a 2002 so I would assume that the carb is a 2002 as well

[boosted3g]

you have an adjustable needle then, no need to get any shims

[kolby2004]

I just took out the k45 pilot jet and put in a k42. Air/Fuel screw is 2.5 turns out. I took out the k155 main and put in a k180 to start testing jets. I got the stumble on WOT so I put in k175. I didnt notice the stumble on WOT and it has alot more power than it ever did with the K155 that came in it when I bought it from someone else.

What I am still wondering about is... I am still getting a little hesitation when I do a wheelie. Once the front wheels are in the air and I let off of the throttle and just kind of feather it, it just kinda cuts out and the front end goes back down. Its fine if it is revved up but when trying to do slow walk wheelies in 1st gear.

What do you think is causing this? If I change the position of the air/fuel screw with this help maybe? Any other Ideas? Thanks

[kolby2004]

Come on ... Anyone have any ideas????

[tim colston]

Originally posted by kolby2004
Come on ... Anyone have any ideas????

Man do a search. They have given you a number of ideas.