Jetting with a pro circuit t-4....need help really bad

[Team Outlaw #34]

ok...i just bought a pro circuit t-4 slip on for my 400EX....I am SOOO confused on what jetting i should do....i live in minnesota...don't have no clue on what the elevation is....

I called pro circuit and they said that they recommend a 158 main jet and a 58 pilot (that confused me, did anyone else call them and get that answer?).....some other people were sayin to use a 155 main with a 40 pilot....

I need to know what to use....because for some reason the pilot doesn't seem right on what pro circuit said...PLEASE HELP ME!

thanx for all of your time

[Leo]

a 158 main would be a pretty good place to start...

as for the pilot they said to use, all I can say is HUH?

try a 40 or 42 pilot.


Leo

[brian400ex]

I also called pro circuit. They said i wouldn't need to rejet. But i went ahead and did. I have a 160 main right now with needle raised one notch.

With those larger jets you migh want to put some vents into your airbox.

[400exNH]

I have a 160 main jet, a 42 pilot, and the air screw turned out 3 turns. What does raising the needle do? Should I do that also?

[400exNH]

oh and I also have 3 1" holes in lid with K&N filter

[brian400ex]

Raising the needle will richen it up at 1/4 to 1/2 throttle i believe. My bike runs good so i don't think i'm running rich. Doesn't foul the plug either.

[Team Outlaw #34]

thanx for all of yout posts....

if i have to small of a main jet or two big of one....could the motor blow up....well not really blow up but just get screwed up?

[brian400ex]

running rich would just hurt performance and maybe foul a plug but, running lead can do engine damage.

[Team Outlaw #34]

so if i didn't change the jets at all....with a pro circuit t-4...it might do engine damage?

[brian400ex]

Heres what you do. Get it warmed up on an old spark plug then put a new spark plug in it. Go through 1st 2nd and 3rd gear and then pull the clutch lever in and kill the engine. Get on it good because the main jet doesn't come in until 3/4 throttle. Don't let it idle. Take the plug out and look at it. If it is white go up two jet sizes and do another plug test. Keep doing this until the plug looks light brown.

[timewass]

If the pilot jet is just for idle up to 1/8th throttle, then how do you tell if it needs to be changed or not? I also have a procircuit T4 and I have a 158 main with the stock pilot. My plug is a nice tan color, no bright white at all. I have no accelleration issues at all. What would be an indication to me that I needed a larger pilot jet?

[brian400ex]

hard starting or bogging off idle

[Team Outlaw #34]

hey tim what is your altitude where u live?

I just called pro circuit again and gave them my altitude (1,000 ft.) and they said that i don't even have to rejet......

I have a question again brian....what happens if you do have a low pilot jet....is that bad for the motor?

[brian400ex]

I really don't think it could hurt anything, just hard starting. I never messed with mine.

[Team Outlaw #34]

hey brian what is your altitude?

thanx u have been a lot of help....sorry bout all of the questions

[brian400ex]

I'm not quite sure. I did have a website that would give you that info but i can't remember it.

[brian400ex]

Its between 1021 and 968ft.

[PismoGuy400]

i have the same question...i called pro circuit one time about a month ago and they told me not to rejet, then about 3 weeks ago i talked to a different person and they told me to go w/ a 158 and a 58...i have no idea where they came up w/ a 58 pilot jet, but ...yea,..im still confused on which jets to use...

does anyone have the pro circuit, that also has the correct jetting?...

i think im gonna try a 155 and a 42...does anyone know if this will be ok?....thanks for all the help (even though this isnt my thread)

[ride300exred]

Run a 158 and a 42 pilot one click up on the needle
Also plug tests arent always right .

[Team Outlaw #34]

what if i dont' put the needle up what will happen? and what does the needle do anyways if you put it up add more air or what? thanx

[timewass]

If you move the clip up on the needle it actually drops the needle further down, moving the needle clip down moves the needle up. Moving the needle down reduces the flow of fuel while moving it up increases the flow of fuel. The The needle + needle jet - govern fuel/air at 1/8 to 3/4 throttle .

Check out THIS (http://www.exriders.com/jetting/jetting.shtml)

[Team Outlaw #34]

do you think that i should move it up or down....i don't know how to do that so do you think it will make that much of a difference?

thanx for your time

[timewass]

Most likely you don't need to move the clip. Moving it will only effect the 1/8th to 3/4th throttle range. If you're doing wide open-4th gear plug chops then it's your main jet that you need to be looking at.

[Team Outlaw #34]

if i don't move it will it effect wheelies?

man thanx for all of your answers....sorry bout all of the questions...i'm just new at this...........

[timewass]

It shouldn't. I don't know your bike's needs, but with mine when I put on my T4 I just went to a 42 pilot jet and a 158 main jet. I never did anything with the needle. It runs great.

[Team Outlaw #34]

Last question....I PROMISE....what is your altitude where u ride?

[timewass]

I usually ride between 1500 and 2500 feet with no problems.
Oh... and don't worry about asking questions. that's what the forum is for.

[Team Outlaw #34]

thanx a lot.....lol i am sure that i'll have more questions tomorrow...thanx again...........

[400exNH]

KID,
I'm running a T-4 currently a 160 Main, 42 Pilot, air screw turned out 3 turns. It seems to run Good. I never moved my needle clip down a notch, which I'm going to try and see if that makes it run even better.

[Team Outlaw #34]

i think i am going to probly do a 158 main and a 42 pilot (my altitue is 1000 ft.)....i think that should work.....