How can I found out what my carb settings are ?

I tried the YZ timing thang last month and moved it right back to WR timing because the carb needed rejetting (could not get the bike to even start) and the prospect of diving in to the unknown (carb) freaked me out.....

Now I REALLY want to do the YZ timing and associated carb re-jetting. The problem is I have NO idea what I have in there (the carb) to start with ? How can I tell ? on EARTH do you get the carb out ? It looks like it is really shoehorned in there and that half the bike should be dismantled to access it.

Any suggestions/precautions ??

Comments Welcome : I think I need a re-jet anyway as I really have to work at pulling a wheelie even in first with 13 50 gearing. I have to get right back on the bike and slam the throttle wide open and eventually the front lifts at high revs. From what I read I should be able to blip the throttle in 2'nd and lift the front easily ???


The Missile

'99 WR400F

Airbox Lid - gone

Throttle Stop - shorty!

Plastics/Tank/Seat - One Industries

Street Legal

the missile

you have a european WR400 the same as me. mine's a '99 as well.

i think your MJ is 168

your needle is DXM on clip 4

your PJ is 45

your PAJ is 75

your MAJ is 200

my bike is

airbox lid off

white bros filter

YZ timing (slightly modified from this)

10oz flywheel weight

PB header pipe

std tailpipe


165 MJ (yours is fine)

180 MAJ

EMM needle on clip 2 (better than me, get an EPM clip 3 or ERM on #4)

PJ is 40

PAJ is now a pilot air screw (adjustable) and turned to 3/4 turn which equals #85.

PS is 1.5 turns from closed (anti CW)



you said....

PAJ is now a pilot air screw (adjustable) and turned to 3/4 turn which equals #85.

Question 1) How do I transform a PAJ to a pilot air screw ?? Or should I just get a #85 ?

PS is 1.5 turns from closed (anti CW)

What is PS (I presume its the Pilot Air Screw??) and what is anti CW?

Also, I live and ride at about 600m with a ridable temp range from about 5C up to 35C. What adjustments would you make to the above settings.


The Missile

'99 WR400F

Airbox Lid - gone

Throttle Stop - shorty!

Plastics/Tank/Seat - One Industries

Street Legal

the missile

the pilot air jets are one size ok? to buy an adjustable screw costs twice as much but of course, you will never need another.

so the PAJ is replaced by a PAS,ok?

the pilot screw (PS) which is different is under the float bowl and you need a small screwdriver to adjust it. you have to screw it right in to closed then unscrew it Anti ClockWise to 1.5 turns, ok?

your altitude shouldn't change these figures.

i should also mention that i run my bike without the Accelerator Pump Jet (APJ) and to do this you just unscrew the pivot bolt for the black plastic arm and that gives you room to disconnect the silver rod. leave it in the hole though so that dirt doesn't get in.


[This message has been edited by Taffy (edited October 11, 2001).]

Hi Taffy,

where did you get the PAS from ? Can you send me ordering details.... I can call SUDCO in the US but the minimum order is putting me off.

Where do you suggest I get the EMM/EPM/ERM/ needle ?? I have asked my dealer - he is checking but I am not hopeful. What alternatives could you suggest, if any.

I tried to find someone else on the forum using the EMM/EPM/ERM and nobody appears to be. Is there anyone out there ??

EKP/EKN seem to be favorites. Taffy, is that because 'we' are Euro 99 riders or what ?? I am trusting you as you seem wink.gif to know what you are talking about!!!

Looking forward to that extra pull.


The Missile

'99 WR400F

Airbox Lid - gone

Throttle Stop - shorty!

Plastics/Tank/Seat - One Industries

Street Legal

may be lyou guys not in the US could help.

oi tried to order a ERM needle and sudco said that they were never imported to this country. they could not help me. i really would like to try one of these(want to buy).

if you guys know where to get one of these lket me know e-mail or just post it

thanx in advance for your help



yz timed now

some mods

Hi Taffy....see above... and also...

dealer came back with following 'suggestion'

EPM/EMM/ERM series needles dont exist !!!

So he proposes....

PJ 40 same as you

PAJ 65 (85 was your suggestion)

MJ 165 same as you

MAJ same as stock (200)

DVR Needle

+ jet needle that is item 17 on the carb parts list which appears to be something the main jet screws into. I guess I have this already as its stock on the WR/YZ.

Let me know where I can order the right parts if the above doesnt ring true.


The Missile

'99 WR400F

Airbox Lid - gone

Throttle Stop - shorty!

Plastics/Tank/Seat - One Industries

Street Legal


The EPM and ERM needles are unlikely to exist anywhere unless they were used in a stock factory streetbike. The EMM will perform the same by shifting the clip position 1 or 2 steps leaner. Just get the EMM and use different clip positions.

EMM#2 = EPM#3 = ERM#4

EMM#3 = EPM#4 = ERM#5


(Oh, and Missile, your dealer is wrong about the EMM, call a Keihin Distributor or order the optional YZ250F needle OBELM part#5NL-14916-EM)

See the worldwide distributors of Keihin at , it lists dealers in England, Italy, France, Germany, and Switzerland.

[This message has been edited by James Dean (edited October 25, 2001).]

i don't want to offer jetting and then have it compromised. i think your dealer has a cheek to suggest slapping any old jet in.

there are going to be keihin dealers all over europe, you''ve just got to try a bit harder.

Allens in england have faxed me today to say they are closing for a week starting today but i would fax them with your request. they're the boys over here. 01949 836733

Fax is 01949 836734.

they will get you everything. i've never checked to see if they do a ERM needle, they definately do a EMM as JD says.

the EKP needle is the same needle EXCEPT that it would sit at clip 1 to the EMM c2. also the straight portion is better in being an 'M' than a 'P'. put it this way are you happy with the start and tickover of your bike now? because you have an 'M' in it now!


the missile


Fabrique et commerce de motos Av. De Préville 6

CH-1510 MOUDON (Switzerland)

Tel. ++41 21/905'33'10

Fax. ++41 21/905'33'13

their web site didn't work so these are the numbers to contact.


Taffy, J-D, thanks for the personal attention... I was getting ready to throttle my dealer in frustration and then 1 hour after I posted my problems...answers from both of you. Great. I cant thank you enough.

Taffy, I knew of Monnier as a specialist bike 'tweaker', they are about 20 miles from here. They do a lot of work for the Paris Dakar....I almost bought one of their semi-tweaked XR650R's (75bhp) but it was just a little tooooo expensive.....good job, because the XR650R would have probably been too much :):D ....anyhooooo....back to the jets issue....

Just called Monnier and they will get back to me shortly. They basically said no problemo :D:D:D

In preparation I cleaned the bike with citric wash this weekend so the carb is looking like new. This week will make my second attempt on the YZ timing and will oik the carb off in preparation.


Taffy, James, I have done the YZ timing thing and went for a rip in the dark last night. Started 3'rd kick. Idle seemed OK perhaps a tad high and response seemed a little 'bogged/restricted' compared to WR timing.

Now I am waiting for the Jets Taffy recommended.

Is there anything I can do/should do to the needle position or pilot fuel screw to improve performance as these are the only variables I have at the moment?



if you have a slight bog off tickover with the 45PJ/75PAJ i think you may try 1 turn of the pilot screw. otherwise just be patient.

just yodel the time away!


Hi Taff,

dealer has confirmed he has all I need except the needle. He can offer an EML.

What do you think ?

Or should I get the EMM/EPM/ERM from the UK ?



the needle EML will suffice. IMHO you will need very low PJ's for this bike.

i'd rather you asked for EMM, EMN. surely they do one or the other?

if not Fax UK and get the stuff from there (at Allen's) trouble is that they do a minimum order cost so unless you can think of a couple of extra bits -it'll cost! i know for instance that they have one x DMM needle still in stock.


Taff, my new jetting will be as follows....

EML needle on (clip 2 ?)

165 MJ

180 MAJ

40 PJ

85 PAJ

Pilot Screw - 1.5 turns from closed

Stock EU Exhaust

YZ Timing

Trust this is OK and lean enough, as the only change from your suggestions is the EML needle. I see from your signature that you are running even leaner. Whats with that ?

By the way what the hell does IMHO

mean ?



i'm really hoping this is going to work!

IMHO=in my honest opinion, i know, i know, embarrasing isn't it! but, as they say, it's only easy when you know the answers.

the only difference between our bikes will be the jetting that you presntly see at the bottom of this message and my cam timing and i'm hoping that means diddly-squeek (FA).

on the 25th october, JD told you that Yamaha have an ELM needle and gave you the part number. if that needle was in my bike right now i would be on clip 2 instead of 2.5, they're that close.

the problem will be relating to any cough or hiccup so i'll do my best.

i was on a 180MAJ recently and 165MJ. the MAJ bleeds air in at the very last few revs. my bike would take ages just eating up those last few revs; even though dirt bike gearing should "smack" into the redline.

put simply, for all the air i was letting in i was having to jet up to keep the balance. the trouble is that the MJ works right down to the pilot area.

you're jets look good, perhaps a little rich what with the '_ _L' needle and 40PJ but let's suck it and see.

did you get the PAS or have you now got the original 75PAJ and a 85PAJ coming?


[ November 01, 2001: Message edited by: Taffy ]


got the carb off last night and spilled its guts. Can you spell D I R T Y ???? I used contact cleaner and it was running off black! All kinds of gook in there....somthing white and sticky too :)

Didnt see the spring fall out from the pilot screw until much later on, there it was lying on the work bench like a turd from an unknown origin. Dont you hate it when that happens.....spent 'a while' :D figuring out where it came from, then saw the photo in the manual which prompted me to tap the carb... the metal washer and O-ring fell out. Good job because I was just about to get the high pressure air to it !

Needless to say I did screw up once...the rubber boot that goes around the Accel pump rod got ejected at 6 bar into the night....I must have a lucky angel 'cause it hit my car and bounced back into the light !! Not important I know but....

My acc pump rod was rusted to hell. Whats with that ?? Lack of attention to detail on an 800$ carb. :D

Anyhoo... guts are now clean and waiting and I think I can get it back together when I get the jets, even though I didn't label all the hoses!

The wife is taking off to Canada with the kids shortly so I will have a weekend of riding/testing to my hearts content. :D

Oh yeah....I'll order the PAS from Allens if I need to jig the jetting further, so far got the stock 75 and the 85 on order. When I talk about it (PAS) to dealers over here their eyes glaze over and assume I must be from 'out of town'.

By the way, what is "taff timing" ?

[ November 01, 2001: Message edited by: The Missile ]

I love my wife.....she just phoned to say my 'package' has arrived. Guess what I'm doing tonight !!!


i did the YZ timing like you and everyone else, i then checked the actual valve timing right down to the Nth degree.

i bought some variable cam timing wheels from Falicon Crankshafts in clearwater, Florida and adjusted the timing to my numbers.

if the exhaust cam rolled clockwise one tooth to YZ timing, i turned it back exactly 1/3 tooth anti-clockwise.

the inlet i moved 1/6th of a tooth to advance it. i had a clear improvement. i'm sure it has hardly any impact on jetting.

can we be clear?

you're on YZ timing and the bike ran well bar a slow speed hesitation, yes?

and you've now got a feel for YZ timing?

it was more powerful, it ran ok, etc etc. just a small glitch at the bottom right?

you build that carb up and let's hope you do fine.

if you have any problems you want to discuss just with me, the envelope logo above this is for pesonal messages.


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