Major Headache

[flick007]

I have a 2003 400ex and Im in the process of installing a new HMF slipon with Uni fliter. I have my pilot at 40 and Main at 155. 2 turns out on the fuel screw and this thing will not idle without being given gas. Higher RPM's are working( no smoke, good clean exhaust sound) but downlow Im getting dirty exhaust. I check the plug and looks like its wet fouled. What can I try next? Ive tried many combination but nothing seems to be work.

I seached this and read though threads for 30 mins before finally asking for help.

[Rip_Tear]

You could lower the needle, if it's wet when it's idling low it's getting too much fuel so that will help.

Are you running with the lid on or off? if it's on try taking it off and see if that helps.

[flick007]

I had the needle in the 4th position was too rich, and is now back in the stock 3rd position. The lid is off.

Once the plug becomes wet fouled is it useless? I was just pulling it out and wiping all the wetness off then putting it back in.

[zje400ex]

when i put my HMF exhaust on...i put a 42 pilot and a 165 main. maybe you should try that.

[Rip_Tear]

Some people might say it is, I'd say no though, it'll be harder to get a reading off a used plug though. You might want to try a new plug though, if that one is week and not able to burn the fuel at the lower RPM's that could be your problem.

I'm not the best at this, but I'd say maybe drop a size in your pilot if it's not idling right and it's getting too much fuel. Maybe you've just got your idle too low?

[j450rking]

i would try putting the stock 28 pilot back in and see what it dose

[RATPACK Z400]

The pilot jet is for fuel delievy in low rpms so that might be your problem.I know my friends installed pipes with filter and didn,t change pilot at all, but it could also depend on altitude as well.put stock in and I think It will be fine.

[the Z Man]

Maybe the uni has too much oil in it, try taking off and see if it cleans out...

[tar]

Check to make sure your idle isn't actually turned really low and I would put the stock pilot jet back in there.

[TRXRacer1]

Mine ran best with the stock pilot jet in there.........

[CarGuy7a]

needle position has little to no effect on idle mixture.

idle mixture consists of the pilot jet and fuel screw and controls that mixture from idle to 1/4 throttle and then the main jet starts taking over the fuel delivery into the engine.

your pilot jet may need cleaning.
fuel screw may need further adjusting.

i also noticed that you are running 2 turns on your 40 pilot. i run mine around 1 1/2 turns out. you might try that.

[maxfior]

Are you using OEM Jets? I run a #42 pilot and a #155 main. I have a pre-filter on my air box lid and (as of right now) a Twin Air filter in. I also made sure to put in a new plug. I would try my setup first and see where you where at. How was your EX running before you added the pipe? Mine ran excellent before the pipe install and all I needed was the proper jets and a new plug since I broke my old one by mistake and didn't even notice it until later! Good luck!

Max