Jetting Qs

244 replies to this topic
  • Taffy

Posted November 24, 2001 - 02:05 PM


i'll let you know how it goes as soon as possible.

you're really hanging out that 1,000th post!!!!

man i've slugged it with you for so long and yet i've no idea who the winner is.

great fun though.

notice how high the needle is sat? up from c2 to c4 and as i've pointed out i can go to c4.5 or c5 i would think. that test on friday i'm sure you'll agree, was quite a lot of changes to do in one go. but understanding the carb is now quite easy.

one thing i don't get, and i suppose i'll have to piddle about to see what happens;is why did the keihin web site you put up say that the needle straight works at 1/8-1/4 throttle? do you think he made a mistake?

they also do a needle chart with all the codes where they indicate that the needle is mainly for starting?

one other thing i need to sort in my mind. the starting jet (#65) what does it do? what effect?


[ November 25, 2001: Message edited by: Taffy ]


Posted November 25, 2001 - 12:07 PM

YO Guys....We need to close out this thread and ge another one going. Took me 3 minutes to load and 10 minutes to print this thread for my book. And I've got fast access. This has got to be hell for folks still on 33kbps.

Bonzai :)

  • James_Dean

Posted November 25, 2001 - 08:19 PM


We all win in these discussions. The bikes were both blue, but with many differences.

The people writing the tuning guides try to simplify things and can't be trusted to do it justice. Often little or no explanation is given because it's too difficult. That's why I like using pictures for this stuff, such as:

The starting jet is only activated while on choke. Not worth spending much time working it.


  • Jim_Bob

Posted November 26, 2001 - 04:14 PM

Gav500. Where did you get the pilot air screw from? My dealer has not heard of it. I will be in Sydney this weekend.

  • gavin500

Posted November 28, 2001 - 01:27 PM

my local dealer got it for me, they got it from Adelaide of all places.
I suspect they got it from "Show & Go" - 08 83760333 ( As they are the australian distributor for keihin carby's.
Since you'll be in sydney, try Nardek - 02 99752650 as they advertise they stock keihin carby's/parts.
Be aware I'm not recommending these companies, due to having not dealt with them personally, I'm merely just pointing you in the right direction to get what you want.

At the risk of restarting the flame on this subject I would NOT recommend that you get a PAS. I would only get one if your into racing and thus peak performance at all times is a must. Of course to achive this you need to invest time, how much time invested is guaged by experience. The normal weekend warrior needs only to look at the work of the above dedicated people in this flame to see what they need. I say this cause the PAS cost's $45, while PAJs cost $13. Other than your stock 75 I would get a 85 and 95 or 100. The difference of 5 either way is not noticable and is trimed in the end via the FS.

Personally I believe I might have stuffed my pilot circuit after screwing the PAS in too tight(a 1/4turn from lightly seated). If you were to get one, of which comes with no instructions, as much as the PAJ is tightly seated - don't do the same with the PAS. Once it is lightly seated STOP!
The problem I have is now I get bog once I snap the throttle on from idle, if the rev's are 1/8 above idle all is fine. At the time of putting the PAS in I also inspected and cleaned the accelerator pump. Before hand I was getting a dribble out of the APJ, but after cleaning it sprays out fuel with great distance similar to a water pistol.
So I suspect 1. I've have crushed a tube or something on the pilot circuit, or 2. now that the APJ is working at full strength I'm getting this famous bog that everyone is talking about.(never got it before though).

Can anyone advise me if screwing the PAS in too much will or won't damage things?
As for the PAS afterwards, it has a light silver ring around the cone end of which fits into the pilot air circuit's hole.

  • Jim_Bob

Posted November 28, 2001 - 02:54 PM

Thanks Gavin500. I have that familiar bottom end 'bogging' and thought that my pilot circuit might be too rich- PJ40 stock PAJ 75?. I thought that a larger PAJ or Pilot Air Screw might help fix this.
For $13 I might just buy a 100PAJ and see if it helps.

  • Jim_Bob

Posted November 28, 2001 - 03:07 PM

Sorry, a PAJ60 not 100. Just checked further up the page.

  • gavin500

Posted November 28, 2001 - 05:32 PM

(smaller PAJ = richer condition, while larger PAJ = leaner condition)

Jim Bob, I don’t know your setup but I would raise the clip position and then if bogging still occurs go for a leaner MJ. Doing this will make things leaner giving more throttle snap. Go too lean and you start to feel like the bike doesn’t have the same amount of power as it did before. This has fixed bog felt when riding and then snapping on the throttle for more power. I don’t believe it will fix bog experienced from nil to 1/4throttle while idling, this is more to do with the accelerator pump.

This nil to 1/4throttle bog is what I’m experiencing at the moment. As for jetting to get this type of bog out I did the following of which had no effect in fixing it. Keep in mind though I may have a stuffed pilot circuit, as explained earlier. So the following maybe worthless info.
PJ of 42, tried the PAS at ¼, ½, ¾, & 1turn. Turned the FS accordingly, bog never disappeared.
PJ of 45, tried the PAS at ½, 5/8, 6/8, 7/8, & 1 turn. Turned the FS accordingly, bog still there but was better at 1turn.
PJ of 45, tried original PAJ of 75. Bog still there.

Tonight I’ll disconnect the APJ and prove to myself if the pilot circuit is stuffed or it is the APJ causing the problem, if this is the case… BK mod here we come. Reasoning for thinking about the AP is that I pulled it apart and cleaned it at the same time as changing from a PAJ to PAS. One thing at a time right?

For reference, I have the following setup –
Stock air filter + exhaust
Snorkel taken out of airbox lid, lid still on!
MJ 170 (Stock MJ 165)
MAJ 200 (Stock MAJ 200)
PJ 45 (Stock PJ 42)
PAS 7/8turns<95> (Stock PAJ.1 75)
PAJ2 90 (Stock PAJ.2 90)
SJ 65 (Stock SJ 65)
Needle DRQ Pos#3 (Stock DRQ Pos#4)
FS 1&3/4turns (Stock FS 1&1/2 turns)

Changing settings at home is ok for ironing out bad bugs but when it comes down to refining, with out a dyno your not in much luck. I found riding in the street is not the same as riding in the bush. So I took the bike out to my fav area and spent a full day changing settings even though I felt the bike was right just to ‘prove’ it was right. The above is what I say is a sweet ride for my bike.

  • Taffy

Posted November 29, 2001 - 12:57 AM


all my tests have been done without the APJ. those with longer memories will know that my first battle was to get people to run without it. the second is to come down on the PAJ.

the bike is far crisper. i've no bog, nor have i had one for a year or more.

watching riders move so slowly in this direction is like having your teeth pulled.

anyway good luck.

it takes 3 PAJ's to cost the same as one PAS. i must have gone through 10 PAS settings so this has been worth it. what with time on the phone and postage i can't see the logic of not recommending the PAS.

all your tests are concealed behind the APJ. get rid of it and start the long but rewarding task of jetting the bike without it.



Posted November 29, 2001 - 07:05 AM

Can someone give me an equivalent clip setting for an EKN against an EKP #4 ?


Bonzai :)

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  • LarryCO

Posted November 29, 2001 - 07:26 AM

EKN #4 = EKP #4...the only difference between the two jet needles is that the EKP has a bit fatter straight diameter...and thus is leaner from 0 - 1/8 throttle. Using one needle vs. the other should have very little impact on your 1/4 - 3/4 throttle ranges.

However, if you mistyped...the 2nd letter is the one in question. Every two letters is a needle clip position. EKP #3 = EMP #4 = ENP#4.5 = EPP #5 = ERP#6. I dont think most of these needles even exist...but you get the idea...

[ November 29, 2001: Message edited by: LarryCO ]


Posted November 29, 2001 - 08:46 AM

Thanks Man....

I'm all over it....

Bonzai :)

  • Taffy

Posted November 29, 2001 - 09:17 AM

tested again for an hour today.

there was no slight back-popping this time and even on 15/48 the bike slammed straight into flat out.

i then adjusted the PS in and out and ended up on 1.5 turns out as the snappiest response.

so thats pretty much it for this needle. when the weather changes and the season's change it might want a tickle. i may one day spot a setting that can be slightly modified. i would love to try the EML and EMN against it otherwise on a straight forward 'E' needle; I'M FINISHED.

i will try the 'F' needle before i sell it and i have a DMM needle and that will have an earlier taper start so i can try that. if it dries out my top end i will do a "personal grind" needle.


  • Jim_Bob

Posted November 29, 2001 - 02:02 PM

Taffy- love ya work! I must admit to being a little slow/timid to take your ideas.
What is the recommended and easiest way to disconnect the APJ? There seems to be several ways.

  • Michael

Posted November 29, 2001 - 03:36 PM how could you even THINK about switching after all this work??

I do understand what you said about the rolling chassis. If that isn't right for is the toughest thing of all to correct - but a Husaberg?? Lord help (but let us know how it comes out!).

  • James_Dean

Posted November 29, 2001 - 08:16 PM


It's hard to believe you could be satisfied with a final setting! What, after about 100 attempts to get it right... :)

Now, a year and a half after I suggested that TTalk owners use EMN or EMP needles in #4 clip, you have concluded EMM#4 is best in your WR. A richer needle diameter with smaller pilot/PAJ and main.

Wish I still had my WR to give your complete settings a try, would do it in a flash now that you have said it's FINISHED! It's great that you have taken the time to share all the variations along the way. (From clip #7 to #2 and back to #4) When inspired to purchase another thumper, there will be jets ready to try it out. Pilot air jet and spring are only ~$8 for the set here from Sudco.

Give the FHM/FHN needles a try if you have the chance to run a more free flowing exhaust too.



  • Taffy

Posted December 02, 2001 - 06:54 AM


remember how the bike used to do nothing on choke and then used to go ballisti, then as i dropped the needle it became spot on and purred like a cat without the revs being either totally dead or raising the roof?

well i have had a couple of interesting runs in the last 48 hours.

yesterday i tried the EKP needle back in the bike on clip 3 as this was the same as the EMM on c4. i can't tell any difference in the needle straight at all. ok i didn't try it for more than 5 miles and i had other things to think about, but it didn't starve the bike at the bottom like i rember it before.

back to EMMc4. secondly the back popping returned all the way down and although i didn't treat it as a back to back test i lifted the needle (to EMM c5)and it was gone and the bike ran great. it had slightly richened the pilot circuit enough to stop it here as well.

so with the needle above c4 and the bike running very rich it seems at tickover i'm thinking of going back to EKPc4. i thought you'd like that one!

so i want to de-juice the choke jet as well if needs be. i'll have a play with this jet as well. i think that i have the original jet which is a #60 in it. i'd like to go down.

lastly i managed to test ride two of the three WR's that came out to play today. both riders run 14t front and usually a WB pipe so they were a little over jetted.

my bike felt stronger at 1/2 throttle plus and the same as below this. i would imagine that with equal gearing i may have had the edge but we rode in such deep mud that it was difficult to tell.

what i did notice was the jolt that the bikes had every time i touched the throttle. it was worth a yard and in many ways it was harder to control but never the less it was there. in the dry it would be a must have.

now that i've got my jetting just about sorted i need to do a lot more for my own satisfaction.

change the choke jet.
try EKP on c3 and c4.
set the pilot circuit again due to lifting the needle.
try the KL mod.

although you said you'd recommended the EMN the other day my memory is of you recommending the EKP originally.

also, if i was on a #200 MAJ the MJ would be about 165 and the needle would be on c1.

as you know 3 clips = 6 letters = different needle.


  • neWRiver

Posted December 02, 2001 - 02:45 PM

Originally posted by Taffy:
i was aware that i'm getting back to nearly standard, it's quite funny how you go round the block and where do you find yourself!

Yeah, funny.

  • James_Dean

Posted December 04, 2001 - 08:07 AM


The EKP was my primary recommendation last year and Yamaha seemed to aggree, using it for the first time in 3 out of 4 thumper models in 2001 (EJP & ELP are within 1/2 clip position). Maybe all the orders for YZ426 needles swayed them. It is an excellent choice for a broad range of altitudes and temps. Funny, the '01 WR never got it!

Personally, I live near sea level and temps average in the 60's here in the wet northwest. The EMN (or EMM) suits cooler temp and adds a smoother transition from idle.(Richer 0-1/4 throttle for those who don't know the codes) It's great for a wide range too, as long as the bottom get doesn't get jetted too rich. Serious racers might want to jet rich with EMM and FHM, but expect to change the plug more often. This would be mostly true for the YZ250F.

-Your original EKP#3 test was probably lean off the bottom. EKP#4 might have been the quick fix.

-EMM#5 is a good torque setting, on the edge of rich.

-EKP#4... Yamaha likes it alot-YZ426=EJP#4 (1/2 clip richer), -250F's=ELP#4 (1/2 clip leaner), I like it too :D

-Will be interested in what you find on the slow jet (choke) effects.

-The "jolt" on those other WR's is probably the accel pump surging the bike forward, where yours is disconnected. I tested without it and prefer the reduced stroke over no pump, but never took it to the level of testing that you have.


New Yamaha part numbers that I would recommend...
OBELP 5NL-14916-EP (nearly same as OBEKP,OCEMP)
OBELN 5NL-14916-EN (nearly same as OBEKN,OCEMN)

OCxxx are brass, OBxxx are hard coated like stock. :)

  • Harold_in_So_Cal

Posted December 06, 2001 - 06:42 PM


About 10 months ago I went to the EKN based on your suggestion and really liked it. My current jetting is: Needle EKN # 5, Main Jet 168, Pilot 48
Air Jet 100, Fuel Screw .75 turns out, BK Mod Done at .5 sec, YZ Timed, Air Box Removed, FMF Powerbomb header, Stroker Exhaust, Stock Air Filter, Octopus removed.

I have an EKP that I've never tried. Do you think the EKP or EMN is a better set up. I hate to tinker and really rely on you guys and your advice has always moved me forward but I do feel that Maybe I could get a little more top end rev.

Suggestions- Thanks



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