some old ? different day

[anderson3064]

i got an '03' 400 ex. only mods are a pro circuit slip on and I will drill the airbox but keep same stock filter for now. what should i jet it to. its winter here in central IN so temp is around 30-40 degrees.
thanks for help, jetting blows my mind

[2004exrider]

You probably won't have to rejet it, but if you do you should only have to go up about one jet size.

Jimmy

[anderson3064]

cool ill just buy a 42 pilot jet and see what happens

[blasterandy]

Pilot wont help. You need a main jet I would go with a 155 main but i would buy a 152 155 and a 160. A 42 will help it start but not much else. To install these all you must do is to take the bottom nut thing out and then you can take a socket and remove the jet. (dont for get to turn the gass off) You may already know this but no sense not metioning. If you need any more help just pm me.

[YBRIK]

Hey anderson i'm from central IN (indianapolis) i have an 07 400EX my only mod is pro circuit slip on as well.I'm installing a 42 pilot and a 155 main this weekend and removing the choke (wont need a choke w/42 pilot).I've reserched and reserched jetting.I'm hopeing that will be good year round but i got a 158 main incase i need it in winter months.Its very easy to change the main jet.I'll let you know how it works out for me.

[firefighterjosh]

My friend has a HMF pipe and we put a 160 jet in it. Not sure how diffrent the pipes are but he also has no holes in his airbox.

[Wheelie]

40 pilot, 150/152 main.

[anderson3064]

ok its done, I put #42 pilot. 155 main, removed the choke and drilled the airbox. havent got to run it yet but it did fire right up and idle.

[firefighterjosh]

Just run it and check you plug.

Black/wet = rich

Tan = GREAT!!!

WHITE = LEAN

[YBRIK]

Hey Anderson could you let me know how it works out? thanks!!!

[firefighterjosh]

Originally posted by YBRIK
WOW your on it.how about you let me know how it works out.did you do it yourself ?was the choke hard to remove?any tips

The jetting part isn't hard at all. Hard to explain were the pilot jet is since I dunno have a pic to show you.

If you look at the bottom of your carb you will see a bolt on the bottom of the flow bowl. Take that off and your main jet in inside the hole. I think it is a 8mm or 6mm can't remember.

I never removed my choke. I prefer to leave it on.

I suggest getting a clymer manual. Really helps alot.


EDIT*** I seen you already did it LMAO I am too tired:scary: Been up over 24 hours and I have 10 more to go:ermm: