I need some jetting help!

I am about to try to jet the 400ex I have. the carb is stock. I have a alum airbox w/ no lid, UNI high flow multistage foam filter, ground out the welds on headpipe and gutted the spark arrestor. what main/pilot/needle clip position should I use or at least start with?
I may take out the choke also but I am worried it wont start this winter. if I do take it out what jets should I use then?

[rdmex]

try a 42 pilot.....152-155 main jets......needle clip on 3rd notch, just some thoughts, tell me how it goes.

Is that with or without choke?
I searched old posts and see where some have said that with no lid to try in the 160 area, that seems high to me.
I see almost everyone runs the needle clip one spot lower.

[rdmex]

with the choke id run a 152 or so. without id run more like 156 or 158

I raised the needle one notch and I can tell a big difference, it starts and idles easy when cold with no choke. even on a hot summer day if the engine was cold id have to choke it a bit to get it running smooth. I think ill pull the choke out of it next but I know if I do it now with the 148 main it'd be way too lean. I was told they are lean in stock form so I know that with my open airbox and other things that its probably lean now so I ll have to get jets before I pull the choke out.
My local shop only has a 150,152,155,160 for $3.95 each and they dont have any 40,42 pilot jets. is $3.95 too high? and since I would have to order a pilot anyway do you think I should just order all the jets 150 thru 160 and 40-42 pilots and wait o do this?

well, being the impatient person that I am I went and bought the 150,152,155,160 jets anyway.
started by removing the choke assy and figured I'd start at the top, put in the 160, I ran 2 passes WOT, killed it and rolled to a stop.
I pulled the plug and the porcelain is white which is too lean right?

[rdmex]

yes, i have a 165 main jet in mine, i dont know why yours is lean, seems 160 is good, lower ur notch to the 4th one down and keep that 160 jet in there and screw your air mix screw all the way in and 3 1/4 turns out. see if that helps, let me know, i am in North Carolina so if i dont respond right away you know why, i am on my laptop and slow internet.

[rdmex]

im curious how you made the rear brake light, can u give me all the details on that please. thanks

Well, I will try to get a 162-170 set of jets tomorrow. I wonder if since I have my airbox is totally open is the reason Im still lean at 160, seems funny that my 400 would take the same jet your 416 does but you still have a lid also or maybe its an altitude thing:confused:

on the brakelight issue, I have a zip with pictures and info in it I can email you, email me at fastnfurious1@msn.com

[rdmex]

i dont have the 416 in it yet, and also i am running a filtered airbox lid so its not open like urs is.

oh ok well then that makes a little more sense why I may need the 165, I just couldnt see it needing the same jet as a 416.
I totally forgot that I had a hotter plug in this thing. I did that back in the winter when I couldnt get it to run and would flood it out trying to choke it too much and foul the plug. would 1 step hotter plug make a difference?
also, the needle clip is on the 4th down already, I did that first off, look a few posts up.
you said to back the screw out but I didnt think the pilot jet or screw made any difference past 1/4 throttle or so??:confused:

[rdmex]

seems to me a hotter plug would burn more fuel which means less air, which means lean. so that is probably why u need sum bigger jets. go back to the stock plug which is a NGK dpr8z and keep the 165 in there and try that. also i didnt know that the screw didnt matter past 1/4 throttle so u got me there.

ok, well I put the stock plug in (DPR8Z) and changed from a 160 to a 165 and it is still white after a WOT run. I am working on it right now and just took a break for a minute so I Iam going to go try the 170.

I saw the pilot screw thing here http://www.exriders.com/jetting/jetting.shtml

well....170 and plugs still white but mid throttle and idle the plug shows tan-chocalate brown. I went and rode it hard for a few minutes and the only thing is after I ran it WOT thru the gears up to 4th and let off the gas it popped thru the exhaust a little.
any ideas?:confused:

Also, 87 octane gas cause a lean condition? should I use 93?
Its like 95 outside with 40% humidity

[Doibugu2]

I am not claiming to be an expert, but from what I have read, the spark plug test does not necessarily work, because of all the additives in the gas. The more important thing is how your quad is running. Also, remember the main jet is only import if your at 3/4 throttle or above. If your not at 3/4 throttle, then your using either your needle or pilot jet.

When is your bike bogging down, 1/4 or 1/2 or 3/4 or WOT? I have not seen very many people use anything above 165 so I would be careful if you go above that.

the quad doesnt seem to have any bog at all. if it wasnt for the plug being white itd be hard to tell anything is wrong.......except that one pop out the exhuast when I let off. I did a search for backfire and saw people describe the same thing and everyone responded that it was lean.....

I have rode it some and it most certainly runs better because my regular jumps I have I could land exactly at the same spot every time and they have gotten very predictable. Now I am still hitting them in the same gear/throttle but I am going 4-5 feet farther and I do seem to be going faster than before. The pop out the exhaust has only happened once.

[Doibugu2]

You should always use 93 octane in your 400. It needs the octance, otherwise your lifters are going to start ticking. And I also believe your right that the lower the octance, you will also run lean. Try running w/ the 93 octane. Also, try talking to a dealer near by and see what they say. I sure if you go in there and explain what you got, someone might be able to help out.

Originally posted by Doibugu2
It needs the octance, otherwise your lifters are going to start ticking
:huh :confused: :huh

My dealer doesnt really know much unless its stock.