Jetting Party Results

The SoCal Jetting Favor thread was getting kind of long - so lets pick it up here.

Conditions: 90 degrees F @ sea level w/low humidity.

My Bike: '00 WR400, DSP w/tapered header & SA, YZ timed, GW & BK mods


<LI>EMN Needle @ #4

<LI>175 Main Jet

<LI>48 Pilot Jet

<LI>Pilot Screw 1.75 Turns Out

<LI>100 Pilot Air Jet

<LI>Accelerator Pump Timing Screw 1.9 Turns Out

<LI>Accelerator Pump Squirt 0.7 seconds (+-)

Khris's Bike: 1998 YZ400 W/Stock pipe


<LI>EMN Needle @ #5

<LI>172 Main Jet

<LI>48 Pilot Jet

<LI>Pilot Screw 1.4 Turns Out (+-)

We did not get Kirk's Bike ('99 WZ) completely worked out. The mid-range and top end feel perfect, but the idle is hanging and the slow circuit feels slightly lean with a 48 pilot jet. Maybe a 50 PJ? I was not sure what to do about the hanging idle thing and don't know what his settings are at the moment, so I won't guess (it's probably on the other thread).

Khris's bike responded very well to the changes. He was running completely stock settings (stock needle @ #4, 175 MJ, 45 Pilot) and was at 2.5 turns out on the pilot screw. After the changes it felt real crisp and pulled harder through the mid-range and on the top end.

As for my bike, well, I thought it could not get any better as it was but decided to experiment a little. After trying many settings and as many test runs, I could not be happier with the performance gain. The difference blows my mind. Thank you James Dean and John in Long Beach! I have achieved super bitchn jetting! It definitely prefers the 175 over the 172 main jet. The needle clip position #4 worked very well at sea level, but will be changing to #3 for 3500 to 7000 foot elevations. The 172 MJ had a flat spot in the upper mid-range and felt weak at wot, even with the clip @ #6.

As for me, I felt like I had no energy yesterday and thought it was due to me being a wimp and the heat. This morning I woke up with a sore throat and have been coughing up smurfs. I hope I did not infect any of you guys with my germs…




N 33'41.156" W117'59.749"

HelmetCam Videos


Glad to hear you have it dialed in and that I could be of help. Have Fun!

James grin.gif

[This message has been edited by James Dean (edited October 21, 2001).]

I DEFINATELY appreciate the help with the jetting. I'm no longer affraid to look inside the carb and will probably be doing it to Travis' bike mid week. One quick question. Ron, would you make changes between Ocotillo and Johnson/Yucca area or even up in the mtns? What do you change?

I didn't realize that the commute was that long from OC. Other then that and the heat what did you guys think of the area? I know Kirk got to see more then Ron and Kevin. There was still TONS of areas that we didn't get to. If you guys are ever interested in making a weekend out of it let me know. Usually mid Nov to the end of march the temps are GREAT!!! Usually perfect during the days and cold at night. It sounds like a pretty long drive for just a day run but it may be worth it for a weekend.

Thanks again for hooking me up with the needed jets and showing me how to do it!!!



"What's that?"

"It's a Yellow 99' YZ400!!"


Good question. Chances are you are going to be okay when you go to JV and even Big Bear. You may experience a slight loss of power due to the elevation, but it should still run okay.

If you want to make the best of it, you can lower your needle by raising the clip by one position (I would not go more than one) to compensate for the rich condition due to the lack of air at higher elevations. What is happening is the carb is using the same amount of fuel but there is less air being mixed with the fuel so it runs rich. By lowering the needle you are introducing less fuel and leaning the mixture.

I take it your happy with the way your bike runs now? Did you notice any flat spots or popping when you got it up to temp?

I really liked the terrain out there. What little of it I did see is very much like what I ride in the high desert. I want to go again, even if it's a day trip. It's not too far for me.

James -


had to change my user name.but anyway i want to mess with my jetting after riding rons bike i think i can clean up my bike. rons bike felt smooth. this is what i got.


pilot screw 1.5?

pilot jet #42


wb promeg shorty w/7 disks

wr timing

no bk mod

any info would be great as to where to start.

the drive was far but i will be back out soon.i have a few friends that want to go camping out there.

ron check out there going to have FIA cars!! should be some fast guys out there.

thanks kevin

[This message has been edited by kev426 (edited October 22, 2001).]


I'm happy to see your going to take a go at it. Its not as hard as its cracked up to be, but be prepared to go in a few times.

You should have received jetting information from white brothers when you bought your exhaust system. It's usually included, but if you don't have it I think we can still get you dialed without too much trouble. It would get you in the ballpark if you had it. I have to say that I am a believer in the e series needles and I highly recommend the EMN from Sudco. Let me do some homework before I try to specify jet sizes.

It was nice to meet you & Kirk. There really are lots of ttalkers here in socal. We definitely have to plan an outing soon. Thanks for the rally info - I'm there!


N 33'41.156" W117'59.749"

HelmetCam Videos

Hey guys, it has been a busy day at the station! First chance for me to get on-line.


It was great meeting/riding with you. I really learned alot about carburation and how jetting effects the performance. Get better and start those workouts. I definately want to plan a ride for the local mtns. and you can show me all the great trails up there.


Just want to say thanks for showing me around Ocatillo! What a great place to ride. I know the conditions were a bit warm, but once the rains hit and weather cools count me in for a weekend trip smile.gif I could tell you were really enjoying the jetting changes on your bike. Enjoyed riding with Travis also. He was great about waiting up for me and making sure that I wasn't lost. His bike will definately benefit from some jetting, I just wonder if your bike will be able to keep up with his after the jetting mods tongue.gif Let me know the next time you head to Elsinore. I'll meet you there, or even Comp Park.


Great riding with you also. Let me know if you want me to come over and help with jetting. I can also pick up all the parts you need from Sudco and bring them over. We need to hook up and ride. Maybe catch some time up at Gorman or you can show me where you and your buddies ride.


Thanks for all the info you set us up with for the weekend. TT is such a great site. Saturday was a prime example of that. 4 riders meeting at a location to learn how to and about jetting and them to enjoy riding together. It doesn't get much better.

Now for my bike. As Ron had mentioned mine was running nice on the top end but I was having with the Idle hanging up or just dying on me in the slow jet area. This is what I am running:

EKP #4

MAJ 172

PJ 48

1.75 turns

YZ timed

TPS pushed back

Grey wire

FMF Power Core IV SA

Stock Header

Now Ron rode the bike and thinks that it could possible be the location of the TPS. I was told to push it back when I YZ timed my bike. Ron suggested moving the TPS back to the WR position. What are your thoughts on this. He also thought that I might need to change the PJ to a 50. That does seem quite large compared to what he and Khris were running. Does the FMF exhaust require that large of a PJ I am kind of baffled. I would really like to get my bike to run like Ron's. I do have an assortment of needles I can try: EMM, EMN, EMP, EKN. Sudco is 4 miles from my work so getting parts is not a problem. Thanks.



Try the stock WR TPS setting as checked by an OHM meter. I would also stay close to where you were before the needle change on your pilot jet/pilot screw position.

From your needle selection, I would use the EKN#4 which may reduce the need for a richer pilot circuit.

Yeah, I'm stoked with how it's running now!! I didn't notice any flat spots or anything. I'll be out there again this upcoming weekend so I'll let you know how it does then also. Next time we go we should maybe try for a weekend with camping. That makes it much nicer cause it's not so much driving!!

Those changes for elevation make sense. It's easy enough that I could do it up there if I"m not satisfied with the performance.



"What's that?"

"It's a Yellow 99' YZ400!!"

Anytime any of you are looking to go to Ocotillo let me know. I'm almost always up for runs out there!!!



"What's that?"

"It's a Yellow 99' YZ400!!"

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