am i running a bit rich?

[ae13291]

ok guys when i bought my quad the guy had the stock exhaust with gutted internals i think, or without a spark arrestor,
i ended up doing the sparks advance key and after testing it i noticed some black smoke a little from the tail pipe and after i put in another stock exhaust with a stock spark arrestor, there was no more smoke, and now that i removed the choke and put in a 42 pilot jet it feels a little sluggish down low, so i have a feeling its running rich, because if i take off the intake lid it will run better, and i also tried on another exhuast and it ran better. is there a adjustment screw i can adjust? i dont know if the main jet is stock or not but i will check. the quad also has a k&N filter too. my elevation 4,524. could the pilot have made me run really rich?? thanks guys

[ae13291]

ttt.... im pulling my hair

Black smoke means rich.
White smoke means water.
Blue smoke means oil.

Bottom end issues/idling or a little throttle you adj the air/fuel screw. If that does nothing then pilot jet needs to be changed.

Mid range/half throttle issues you adj the needle.

Top end issues/full throttle you change main jet.

Spark plug should be tan.
Black plug means rich.
Black wet plug means burning oil or very rich.
White plug means lean.

[Eviltanker]

You are rich, really don't need a 42 if you have stock exhaust and stock airbox on yet. back down to a 40 and take the airbox lid off that will fix it. If you want the lid on I would say put the 40 in and a fresh plug, start there. you might be good with the 38 in there yet.

[ae13291]

im going to check the plug, since i put it in new b4 i took out the choke. i will go back to a 40 jet and mess with the adjuster screw, and how do i adjust the clip settings on the needle? how do i do that and wat would make it more lean, going in or out? thanks guys

[400exrider707]

Do you ride in an area that requires the lid? If not ditch the lid, ditch the K&N, get a UNI, the do the 40 pilot with a 150ish main, drop the clip on the needle one position down. If you get an exhaust, with that do a 155ish main, 4th clip down on the needle (same as other instructions) and 42 pilot.

[Eviltanker]

What year is the 400? 05' and newer don't have the adjustable needle you'll have to buy one. I agree with 707, ditch the K&N. Uni is a much better filter.

[400exrider707]

Originally posted by Eviltanker
What year is the 400? 05' and newer don't have the adjustable needle you'll have to buy one.

Thanks for pointing that out, I plumb forgot. Been a while since I worked on an EX.

[Eviltanker]

No Problem.

Originally posted by Eviltanker
You are rich, really don't need a 42 if you have stock exhaust and stock airbox on yet. back down to a 40 and take the airbox lid off that will fix it. If you want the lid on I would say put the 40 in and a fresh plug, start there. you might be good with the 38 in there yet.

If you take the lid off you have to adj the needle.

And k&n flows better than uni. Me and many other people have used k&n with out sucking dirt in. The guys sucking dirt in with their k&n's are the ones that dont know how to oil them right.

I ran 5 years with a k&n and with the whole air box removed and ran in clay dust and normal dust and never once got a speck of dirt in my intake tube. Went threw shallow mud and water to and the filter location dont get much water/mud by it. And K&n cleans way easier and is way less messy compared to uni.

And never remove your air box lid before getting the pilot and main jet set right. It will just make getting your engine to run right so much harder.

[ae13291]

i really appriciate all the responses guys its a 02 400ex btw. removing the lid would be the last thing to do, i like to go in pretty deep mud and even the snorkel tends to get some mud through it. so i will put in a 40 jet and check my main jet and put in a 150 right? also move the needle down one step? and then fine tune it with the external adjuster screw? thanks alot guys i will start this first thing tommarow morning

[Eviltanker]

Originally posted by ltr450fly
If you take the lid off you have to adj the needle.

Not with the stock setup.

[JDMThoughts]

I would adjust the air screw first, that is a large pilot for a stock bike. Close the screw all the way in and see what happens, if the bike runs better then you need to remove the pilot jet and go down one size. If you turn the screw more than 2.5 turns out you should bump up the pilot. Knowing your main will help diagnose what your top end is like. Every bike is different, just like every location is different. You just gotta keep fiddling with it.

[ae13291]

does bogging signify running rich? i have first been trying to do it in neutral by free reving it. and when i drive it i cant really tell if its running rich down low rpms, i can kinda smell a gasey exhaust but i know its not popping on deceleration, im going to try and make it a bit leaner again