Not a jetting problem?

[skemp]

I understand the whole jetting thing for the most part, but could something else be wrong? I have a K&N air filter, Greedy er... White Brothers exhaust, and 3 1" airbox holes, and my elevation is about 800 ft above sea level.
I have been trying to get the jetting right on my 400EX for about two months now, with little success. Today I got two new spark plugs, and decided to rip into it again. I rode for about an hour with the new plugs to get some color to them, and then started doing wide open plug runs. I first tried the 160 I have been running (the whole time thinking I am ruining my motor from running lean), and the plug was as white as Marilyn Manson's skin. I went right to a 170, and it was just white. I then tried a 175, and I got a gray color. Now I am at a 180, and it is a darker shade of gray. I know myself that anything over a 165 - 170 main jet on a stock 400EX is crazy, and I am at a 180, right where I was when I last asked about jetting. I have raised the needle one notch and it is the dynojet needle that comes with the jet kit (which I found worthless).
I have checked every intake point on the quad, and everything is looking good. I cleaned my filter yesterday, and the petcock flows just fine. The carb is all clean, and as far as I know, everything is tip top on the whole machine.
My question is, could something else be wrong to create this condition? I don't know of anything, but maybe I am missing something...

The quad ran fine with the 160, but the mid range feels choppy, so does anyone have any suggestions for a needle position (Dynojet needle and I don't have the stock needle) with my setup? The 3/4 to WOT is choppy now with the 180, and got worse as I went up from the 160 to the 180.

In a perfect world, someone with a WB exhaust, K&N filter, and airbox vents or no lid could tell me their setup, so I could give it a try and work from there. Thank you so much for any help you can give me.

[400exRacerX]

i live around 800ft above sea level, and run the white brothers slip on with the last disk out, making me have no spark arrestor and its now pracitcaly a free flowing exhuast, K&n filter,and outerwear airbox lid. so i practicaly have the highest flowing intake and exhuast and i am running a 152 main and a 40 pilot. 185 seems very very high for just a filter and pipe.

[skemp]

I know, it seems very high. I went out again and did it 4 more times, run it check the plug, run it check the plug..... I took a picture of the best (darkest) color that I got. This is with a 180 and it runs like crap.

[inacoma91]

Well I have pretty much the same set up as you only i have the Pro Circut T-4. Only thing i did different from the directions was i raised the needle one notch from the recommended directions. I am running 3 turns out on the air/fuel screw. 170 main on the dynojet kit. Ummmmmm I cant really think of anything else. I am running right on too. Nice brown color. You might want to try restiricting your air flow intake to richen it up and see what happens. Try to cover up your air lid holes. or wrap something around your air cleaner then do another WOT run and then test your plug. I dont know.................sorry but i am not much help!!

Andrew

[nakomis0]

make sure your fuel is flowing correctly. Use an older plug with some color already on it, gets you a reading easier. Either keep going up with the jets or take it to a professional. I have heard of a few fluke 400exs that seem to need larger jets, but yup getting around 180+ seems very high. But I'd believe it.

[skemp]

Thanks for the replies, but keep them coming.
I have kept it up, with no success. I put the stock filter back on, and it was still white, so I then covered the vents in the lid, still white. I then wrapped duct tape around the stock filter and left about half of it uncovered, and got a little color, but it was pretty much white. I think I will go back to the old spark plug and see if I can get anything out of that. This is starting to get on my nerves, 6 hours of doing this and no success! I don't want to take it anywhere, but I might have to. You see, I was using an older plug, but I was getting a very light gray color using a 180 main jet. It is so weird, it feels strong with a 160 to 170, but the plug is crispy white. When I go up from a 170, it runs horribly, but the plug is the same exact color.
I will try the older plug, and take it slowly, and try not to get frustrated about it. I just want to stop worrying about damaging the motor whenever I ride it.

It may seem like I am a moron that doesn't know what he is doing, but I am fairly mechanically inclined, and usually know what is going on, but I think in this situation something else is wrong. I have done the same thing over and over, and really had no success.

Thanks guys, any more help would be great!

I am running a 170 main with no airbox lid and my quad flys. But I haven't done a plug test yet. I hope I don't have this problem too. I will do a test tomorrow.

[Wheelie]

I am running an E-Series and Modified stock filter with a hole in my airbox lid about the size of the lid itself. I am running a 160 main (thinking about a 162 or 165) and the clip on the needle lowered one notch (stock needle).

Not to question your mechanical abilities, are you running it long enough to get a good color reading?? A 180 seems really high.
Try to pull off your silencer to see what the color is inside of the header pipe. Also the plug cap might be shorted out, which will cause more resistance resulting in more voltage and hotter fire. A long shot, but a few more ideas. If it runs best within the 160 range, my guess is that is probably the right jet. Good Luck
!!

jja

What do you mean by choppy??

[Guy400]

Do you run with your bike with the petcock at "On" or "Reserve"? I may be way off base here because I don't know the 400 that well but many bikes use a small filter in the gas tank. When the gas is "on" it flows through a 1"-2" stem that extends up into the tank with a small filter on the end of it and when you go to "reserve" it bypasses this stem and goes straight into the petcock. This is how most setups allow for a "reserve" without running 2 tanks. It's possible that you got some crap down in your gas tank and it's impeding the flow ever-so-slightly. Not enough to hurt performance all that much but enough to throw off plug readings.

Another long shot is some people have talked of their local gas stations in which the fuel has detergents and other additives in it which will always burn white on the plug. This could explain why the bike runs so strong around the 160 range but craps out at WOT with the 180. You may be jetted correctly at 160 and the plug comes out white. The only way to tell 100% if you're jetted correctly is to have an O2 test done. Call around to local car repair facilities and ask them if they do "sniffer" tests. They could stick the wand in your quad and tell you your burnt air/fuel mixture. Good luck, keep us posted!

[Leo]

I might be mistaken, but I don't think the Dynojet #'s correspond at all to the Keihn numbers..

I think there is a huge difference between a 180 keihn and a 180 dynojet main...

(you said you had a dynojet needle, so I'm assuming you have the whole kit with the dynojet mains also....)

Leo