Just ordered exhaust, couple ?'s

[DP400]

I just ordered an HMF sport slip-on for my 2002 400ex. I've searched all over and can't find anyone with the set up i'm going to have. Just wondering if someone could please help me out. I even called HMF and thier recomondations seemed higher then what I see even guys with engine mods. I'm just wondering what jets I should get from the local dealer before my pipe gets here. I do want to run kiehin jets. I'm in NY, elevation is 510 FT, weather is mostly high 20's-35 winter and 80's during summer. Motor is stock, I'm going to grind down welds on stock header, running air box lid on also keeping my choke, and have a k@n air filter. I also got the quite core for going out in the woods, will this change the jetting? sorry for making another post I know some get sour about it, but I would really appriciate any help or spot on answers. Thank you in advance.

[bigredisb]

I have a similiar setup on my 08 400ex but with a uni (no debate needed!) and a Lexx with the quiet core. I run a 40 pilot and a 150 main and it seems pretty good. It gets a little black on the plug if it idels for a while so its plenty rich with the 40 at idle and if I run a new plug at WOT and check with no idling its light brown. Its worth the shot I typically buy 3 jets at once so I bought a 150 and sizes bigger just in case.

[ginobili07]

I also have a K&N and HMF slip on with my 02 and am ognna grind down the header in the spring, anyway i have a 150 main and kept the sotck pilot and have the A/F screw about 2 turns out and it runs perfect.

[DP400]

Thanks guys for your help. I was thinking of jumping up the pilot to 40 and main to a 152. I know alot of you guys run HMF, does anyone else have any suggestions? thank you again.

I would try a 40 pilot and a 152 main. See how it runs and make adjustments to the needle or jets. Order a range of jets at once to save time and money. If you plan on doing any future mods besides that maybe removing the airbox lid just get a larger range of jets. I ordered 152 - 162 running a similar setup, I have the airbox removed and the choke. I ended up with a 158 main & a 42 pilot.

[sprayedgt]

Originally posted by DP400
Sorry for making another post I know some get sour about it

Yeah the usual few as always will say you should have searched :rolleyes: Your questions are welcome here. I would start out with the 150 and see how it runs. If it's really cold you may want to go ahead and just do the 152 and the 42 pilot. You need a little more fuel in the cold weather. BTW if you do the 42 pilot you can do away with your choke for a little extra air flow.

[dobber21]

just wondering wat does grinding the welds on the header do? to me that doesnt make sense

[powermadd400ex]

Originally posted by dobber21
just wondering wat does grinding the welds on the header do? to me that doesnt make sense
stock headers are very restricting. grounding down the welds acts as a aftermarket header.
when you ground them down it lets more air flow compared to stock. hornetgod13 posted a picture showing the comparison awhile back.

[stcblack450r]

my 400ex had a stock motor, moose air filter, and HMF sport series slip on...i ran 42 pilot and 152 main with the air box lid on. my climate is about the same as yours and i had no problems with the jetting no matter if it was summer or winter

[dobber21]

wat welds are u grinding

[powermadd400ex]

this should answers everyones questions on header welds
http://www.exriders.com/vbb/showthread.php?s=&threadid=334885

[Ntensweapon]

Originally posted by powermadd400ex
this should answers everyones questions on header welds
http://www.exriders.com/vbb/showthread.php?s=&threadid=334885



Check out the 4th post in that thread. When did that happen?

[racerdan24]

I have a friend of mine that put a slip on exhaust and never even touched the stock jets because he was too cheap or too lazy to do it. His seems to be running fine. Is it necessary for certain areas? Or is it a trial and error thing?He runs his with stock air box and i believe a twin air filter.

[powermadd400ex]

Originally posted by Ntensweapon
Check out the 4th post in that thread. When did that happen?
he finally got banned
he went off on a couple ppl and pappy just up and banned him :D
i think it was for the best.

[Mustangous]

Originally posted by powermadd400ex
he finally got banned
he went off on a couple ppl and pappy just up and banned him :D
i think it was for the best.
I'm a newbie here so when i first saw that i thought that he got banned, but then i thought he put that there???

[cdubbzz]

ride in similar weather in NJ
42/155 in winter
40/155 or 152 in summer

[DP400]

Thanks so much guys for all the replies. going up to dealer tonight going to get 150-155 main and a 40 pilot, new crush gaskets for the header, also a plug for my new can.