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Discussion Starter · #1 ·
Hey guys, I was wondering if you could make a suggestion on ballpark jetting for my 400ex:

2000
stage 2 hotcam
11:1 wiseco piston
k&n filter, no airlid
fmf powerbomb header (being added now)
white bros e-series exhaust
roughly 1045' above sea level, 90* temps

also, at this power level do you think i should be looking into 450r carbs?

if you guys could give me jetting for both stock, and 450 carbs that would be great! thanks a bunch.

matt :happy:
 

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175 or 180 on the main about 1/2 to 3/4 turns out on the air screw from it's current position.
 

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Discussion Starter · #3 ·
175 or 180 on the main about 1/2 to 3/4 turns out on the air screw from it's current position.
the quad runs well as is, however im not positive that its spot on (just riding it, recently purchased). should I just do as you suggested, and tweak it from there?

thanks for your help
 

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I would invest in 3 or 4 new spark plugs fill the tank with no less than 93 octane (premium) ride the quad around for about 20 min. to get it good and warmed up. Then find you a good long safe straight away and run it through the gears when you get to 5th wide open hit the kill switch THEN pull in the clutch and stop. pul the plug and see what the color is. You are looking for a nice cardboard color. Do this before you do any jet changes. If your plug is too white put the airbox lid on and put another new plug in and do the same thing. if it's color starts turning more towards that cardboard color your looking for then you can go up 2 sizes on the main jet eg. if you have a 148 in it now jump to a 152 if it's a 150 jump to a 155 ect ect. if it's darker than the desired color remove the air box lid and put in another new plug and try it again you should be good to go then. Don't throw the tested plugs away they are fine by the way if you have to change one back in just ride it awhile and it will burn off clean.
 

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Discussion Starter · #5 ·
i gotcha, very similar to how i tuned my trans am for nitrous. at least i dont have to read 8 plugs for my quad :)

unfortunately the best gas we can get around here in 91, should i be looking into mixing in some 110 with the 91 considering the compression my EX has?
 

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Nah premium pump gas is fine with 11:1 you should be fine with 91.
 
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