questions JD?

hello mate

question; what is the measurement used to get the middle suffix? is it to the start of the taper or as i think you wrote-to halfway down?

what relavence is the starter jet-any info on it's circuit?

if for example one needle is a DTL & another is a DTS does that mean that because the straight bit is different that when the tapers start at the same point one will be narrower than the other at any given point?

in a different example, if one needle is a DXM & another is a DKM & therefore the tapers start at different points on the needle, doesn't this also mean that at any given point one will be narrower than the other?

have you been experimenting lately?

what about those APJ diaphram's are they in yet?

i sounded abrupt other day. don't put anything in your pipe! sorry.


[This message has been edited by Taffy (edited 01-09-2001).]


The middle letter refers to a distance from the top clip slot to mid-taper at a diameter of 2.515mm. This is labeled as L1 in the FCR needle pictures at . It has an effect on where the taper starts but the taper start changes when the straight diameter changes.

All DT- needles have EXACTLY the same jetting past 1/4 throttle.

DTL and DTS have their tapers start at different heights. Because DTL has a smaller straight diameter it's taper starts lower. After the tapers start, these are identical needles. You can make a DTS into a DTL by grinding down the straight diameter.

DXM and DKM have the same degree of taper but the whole tapered section is shifted lower on the DX- needles. DXM will run much leaner past 1/4 throttle than DKM when using the same clip position. Yes, for the whole length past 1/4. Before 1/4 they have the same diameter 2.715mm (M).

The clip can be shifted to make needles run identical when the 2nd letter is close. Each letter is 1/2 clip for these (skips O). K and X are 6 clips apart (5.4mm= 6 x .9mm). This means that DXM#7 will run the same as DKM#1 all the way through the range.


Note: my current EKN#4 has it's taper start nearly the same location as your DXM#4.

Starter jet? I don't mess with it. It starts perfect and doesn't effect anything after the choke is off.

The APJ diaphrams were not available. They never came.

No experiments lately, running the same -

#48 PJ

#100 AJ

1 turn out

EKN#4 (same as EMN#5) (and sometimes a FMN#5 modified needle)

#170-#172 MJ

45-55 deg F

0-5000ft elev

YZ timed

YZ exhaust with a screen in it for S/A (a little restricitve on top end)

Air box lid removed

Fires off easy, rips hard through the mid, top is OK.


[This message has been edited by James Dean (edited 01-09-2001).]

according to my figures the uk bikes run about one or two clips leaner. but then again as i've told you before the better they run the jetting goes down!

my DXM is on the 6th clip accoding to my diary. that's the same as your DSM on 4th.

will be trying the EKP very soon but for it to take over from the 'DSM' (if i had one!) the EKP will have to be on clip 1!

that also dangles the EKP down an extra 7mm or so, making it even leaner on near full throttle.

anyway i'll try it.

went back to standard 45 pilot, far beter straight away. 1 3/4 turns out at the moment.

had the slide cutaway done. 0.3mm off, will try it some time, but i must cut the jetting down as much as i can for valid results.



The equivalent codes-


The middle letter is not directly referring to where the taper starts, so EKP will need a clip of #3 or #4 to be close to your DXM#6.

Example - Last summer a friend with a '99WR swapped a DTM#3 to a EKN#3 and changed NOTHING ELSE. (The tapers start at nearly the same place on these.) It worked perfectly with a boost to his mid-throttle power. EKP is closest to EKN.

This leads me to suggest trying either EKP#3 or EKP#4.


(Note for others: absolutely DO NOT run an EVP needle, way too lean)

How do I post a question

Thank you james-dean.

That was amazing post.packed full of hard to get info.

Thanks for demystifying the needle can be very confusing.

I can't post a question!!!! I need help!!!

Hi Thumpers, help with a tech question please.. Why is my '03 WR450 not returning it's oil, back to the oil in frame tank??? Filter & case o'rings changed.. Lines cleared, gauze filter cleaned.. Where's the fault here people??? Worried about distance rides

An oil passage is clogged somewhere. Don't ride it at all until this issue is fixed, it may even be your oil is draining put somewhere? If it is either of these issues, you can seize your piston so DO NOT ride it all until the issue is fixed. Do you have to put oil in your frame?? One of the lines that go from the engine to the frame may be clogged? If you know how to rip your engine all the way down to the cases and you are willing to buy a new gasket kit, rip it apart, but first I'd check the lines if you full your frame with oil. Take them off and put a compressor with 50-60 psi to it and blow them out only if the frame is filled with oil. Like I said, it may be that an oil passage in the engine is clogged.

ZZJJJHHJHUJJHUUUJJHHJUHUUHJJJJJUHJJJJJJJJJJJJHJJJHHJHIJJJJIJJJHJJHHQYesSassaFA, it's an oil in frame..1100cc in but with no return obvious.. Just had a full top end rebuild, airline has been used to clear what I can access!!!!

Edited by Stitchyg

I could rip it all back down again, but was thinking the oil pump was shot, but there's oil getting to the top end, ripped into the engine from both sides, oil present, but there would be, it's all in the sump!!!! Top end must just be pressure fed by the crank etc Can I air push via the piddling oil filler????

Not sure. I'd rip the engine apart. There may have been a gasket put on backwards, blocking a passage.

I have slippage and noise when shifting in lower gears on my 96 Yamaha warrior.What could this be

The pin that's on the end of the shafts that shifts the gears. The shaft/pin needs replaced

Where exactly is pin located.

The oil return is sorted!! A simple split O'ring on the oil filter housing. The bottom right one allows for the oil to return to the oil tank/frame. Without a good seal it all empties into the sump..

On the shaft(s) for shifting. You'll have to split the case.

I cant post a question, and i cant edit my profile....any help?

How do I post something on here

I need a new carb for my 98 wr400,old one shot.anywhere i can fill my head full of info? I heRd. Newer. From yz how new? And other mods, thanks

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