Should I use HMF factory main jet in '02 400

[stresy01]

stock '02 400ex
HMF sport series slip on
no air box lid

I recently bought a candy red sport series slip on. The jet they send you is a 165 main and they don't recommend changing the pilot jet... I am running it with the air box lid off and will move the e-ring on the needle up the 4th position. Should I just go buy a stage two jet kit and not piss around with HMF's jet? And will moving the e-ring on the needle give me a little more in the mid and high ranges?

thanks!!!

[stresy01]

P.S. I have done a "search" and did not find what I was looking for so any links would also be appreciated!!!

[krt400ex]

OEM brand 155 main, 42 pilot with screw 2-2 1/2 turns out, and mess with the needle...either 3rd or 4th position

[AbnMP13]

I believe the pilot doesn't need to be changed unless you have trouble cold starting.

Here's a helpful thread.

Pilot Thread (http://www.exriders.com/vbb/showthread.php?s=&threadid=221742&perpage=13&pagenumber=1)

[GPracer2500]

With that settup I'd guess you'd need to be somewhere between about a 155 to a 165. The only way to know is to test. The jetting supplied by exhaust manufactures tends to error on the rich side (which is understandable--too lean can create damage that too rich can not). Your local elevation, local riding temperatures and humidity, and local gasoline composition will all make a difference. Even your air filter oiling practices can push you towards one size or another. Some folks like to jet for best power while others prefer to stay a tad rich to help cool the engine. And there's probably a bunch of other considerations I'm not thinking of at the moment.

Basically, no one here can tell you exactly what jetting will be right for you and your quad. You can take someone's advice (HMF, someone here, someone local to you, etc) and call it good enough. Lots of folks do just that--but some luck will be needed to end up with specs that are just right. The alternative is to do the testing that will reveal what is just right.

$0.02

[krt400ex]

Originally posted by GPracer2500
With that settup I'd guess you'd need to be somewhere between about a 155 to a 165. The only way to know is to test. The jetting supplied by exhaust manufactures tends to error on the rich side (which is understandable--too lean can create damage that too rich can not). Your local elevation, local riding temperatures and humidity, and local gasoline composition will all make a difference. Even your air filter oiling practices can push you towards one size or another. Some folks like to jet for best power while others prefer to stay a tad rich to help cool the engine. And there's probably a bunch of other considerations I'm not thinking of at the moment.

Basically, no one here can tell you exactly what jetting will be right for you and your quad. You can take someone's advice (HMF, someone here, someone local to you, etc) and call it good enough. Lots of folks do just that--but some luck will be needed to end up with specs that are just right. The alternative is to do the testing that will reveal what is just right.

$0.02


i agree 100%. the jetting recomendations that came with my yosh system said to run a 178 main, and stock pilot :huh

[BUBBA Livesay]

when you get the jetting and what not figured out let me know how you like the pipe. i was wanting one for my 02 400ex as well.;)

[MichiganMOOSE79]

K&N STAGE 2
134 MAIN
3RD SLOT ON THE NEEDLE FROM THE TOP
GOOD START