400EX fouling plugs.....

[flyin_high]

i have a 2003 honda 400ex with a supertrap IDS-X exaust on it and dyno jet kit with a 165 main jet which it says to install for the altitude that im living in. my air/fuel mixture screw is turned out 3 turns. the problem is that its fouling up plugs like crazy. i can put a new plug in my bike and in no time ya take the plug out and its so black with caarbon that ya the plug wont fire anymore, any ideas whawhat i could do, example: turn th air fuel screw out more??? any one with any ideas let me know, thanks.

[2004TRX450R]

make sure you aren't running it for any length of time with the choke on. Also does it run blubbery? Sounds like it is way to rich. You need to figure out where it is rich (high rpm, mid rpm, or low rpm) and adjust accordingly. You could try turning the fuel screw in. You might need to lower the needle or install a smaller main jet though.

[400EXSTUDMUFFIN]

I think his problem is in the dynojet kit

There is a big difference in the sizes of dyno jets and kheiln (I can't spell)

I think 146 or 148 dyno jet is where you need to be for those mods you might want to try that

First off do not touch the choke when starting it. PERIOD

Do you have a airbox lid on??

What is your altitude???

[cals400ex]

Originally posted by Rico
First off do not touch the choke when starting it. PERIOD

Do you have a airbox lid on??

What is your altitude???

yeah, i agree that most bikes don't start with the choke. however mine is weird. i have the stock 38 pilot, a 40, 42 and 45. mine will NOT start with any of these without the choke. i have no clue why. i set my fuel skrew between 2 and 3 turns out with each pilot. i also even tried pumping the throttle a couple of times before trying to start it up. mine plain and simple won't start without the choke unless its 60 or above. maybe i need to try a different technique, but i don't know what?? with the choke however, mine fires right up whether its summer or zero degrees outside. my friends bike however starts with the choke off most of the time. we are running the same mods and same 42 pilot jets right now. both running the same fuel and both have several new plugs on hand. i don't know what it is. i do know if i have the sparks ignition box on that mine won't start with or without the choke unless it is about 50 degrees. i assume your running the stock pilot with 3 turns out??

[LazeR]

Dynojet 175 main does sound a lil rich.........i think it requires me to use a 146 dynonet main with a K&N filter and Slip-on and im at like 400feet...... I can't be positive that its the 146 but if i remeber right it is! I can tell ya more when i actually get my slip on! also what is your elevation? Does it seem doggish anywhere through the powerband?

[sprtrx300ex]

If your lid is on, try this:

146 mainjet
42 pilot
2 - 2 1/2 turns out
Also , make sure your exhaust connections are all tight, If you notice even the least bit of black soot, it will be popping on decell.

You sound really rich on the main, which could be causing a buildup of carbon on your plug.

This is how I start mine.

Pump throttle twice.
try to start
Repeat this
If it doesnt start after about 3 times, then put the choke on 1/4 -1/2 try again, without pumping, then try with pumping. It takes time to get the feel on it.

[fmf400ex03]

i would call super and see what the say cuz dynojet isnt always the right i tried that wit mine and i fowld plugs and then i put what fmf said and and learned how a carb works and im runnin 2 sizes bigger with a lid they cald for a 165 i have a 170 and the other kid i ride wit cant touch me and hes got the 165 in his so keep that in mind

[cals400ex]

Originally posted by fmf400ex03
i would call super and see what the say cuz dynojet isnt always the right i tried that wit mine and i fowld plugs and then i put what fmf said and and learned how a carb works and im runnin 2 sizes bigger with a lid they cald for a 165 i have a 170 and the other kid i ride wit cant touch me and hes got the 165 in his so keep that in mind

just remember jetting is not the only factor. tire sizes, tire weight, sprockets, mods, properly adjusted throttle cable and needle jet holder, etc all make a difference. also, some bikes seem to be quicker from the factory anyways. i will tell you that with my 11 compression 406, stage 2 cam, uni filter, sparks pipe, etc that my bike runs the best with a 158 main jet in for my elevation of 625 feet and a temp outside about 45 degrees. i will notice that each size i go up i won't notice too much power loss, but i will be going slower towards top speed. for example, with my 158 in, i slowly pull on my friend in 5th. when i have the 162 in, he slowly catches me in fifth. the difference is more noticable in the upper gears and one or two sizes on the jet is harder to notice in the lower gears. i know many people don't agree with my jetting, but i find what works best for me. i would not put in a 165 in my built bike unless i had my air box lid off and it was about 20 degrees or colder out. good luck with what works for you though. ;)