YZ timing with WR stock needle?

I changed to YZ timing about 2 years ago and it seems to run ok except for a bog when I snap it of idle and a little rough at 1/2 to 3/4 constanst throttle. I'm still using the stock WR needle. The good news is that I've never fouled a plug like alot of guys have here in the high altitude. Am I running too Lean? The plug is brown right on the tip but black on the bottom part.

1.) How can I get rid of the bog off idle?

2.) Should I use a different needle to go with the YZ timing?


'99 WR400

baffle and airbox lid removed

Throttle stop cut.

Grey wired disconnected

Stock Jetting except 70 main and clip moved one position leaner

Altitude: 7,000-10,000 ft in Colorado

I got rid of the bog with a P38 from factory r&d. I believe there is a mod on the board for the 98&99 WR which would save you $80. As for jetting I don't know what to say, still working on my jetting. Good luck with your fix.

No really guys I need help. Colorado guys What jetting are you running to deal with the altitude? Check the beginning of this thread for my jetting specs. Thanks in advance.

Hey man, It is still winter, should't you be skiing? At least that is what you always tell me. :)

Currently I am running DVB, 4th clip with a 45 pilot and 170 main. I have been running that for a while now. I also am not happy with the 1/8 response. I'm not fouling plugs, but it does bog quite a bit until it warms up.

I have to look it up, but I have information from James Dean suggesting a EKQ (?) needle. Problem is, I can't find it anywhere. I'll forward that info to you if I find it.


From one CO boy to another...

Two "to-do's" for you...

1. Do a search out there for the "BK mod". $15 minutes of time and $15 will permanently remove that off-idle bog. Someone has even put Home Depot part numbers for the parts you'll need to do the job! Apparently, the accelerator pump is way overdesigned for this bike. The "squirt" duration should be 0.5 sec or so. Off the shelf they're setup somewhere around 3 - 5 seconds.

2. My buddy has basically the same setup as you and is running: 42PJ/75PAJ/DRR#3/160 main/200MAJ. Really close to your setup except a bit leaner main (all other parts are stock). I'm guessing you're a bit rich on the higher end of things...thus, go down on your main jet. I'm also assuming that the DRR needle is stock in a 99 WR...so if it isnt, let me know and I'll adjust my suggestion accordingly.

2a. MUCH BETTER THAN 2. See my setup below in my "sig". Except for the YZ timing (which I havent had time to complete yet), my bike runs great! A couple of other Denver folks also run the same EKQ needle. Try it...you'll like it! By my best guess (having ridden both my friends and my own bike), the YZ timing causes his bike to pull harder thru the midrange than mine...but not nearly as much as it did before I switched to the EKQ needle. The combination of the two should absolutely rip! FYI...I've ridden this jetting at Rampart (7K - 10.5K ft) and the bike has performed flawlessly. You might want to richen it up just slightly for local Denver track riding (EKQ#4/165main?), but start with what I've got and go from there.

Hope that helps! Drop me a personal message if you want further help...


OK Kerry, I searched the archives and found the info:

James Dean suggested the following:

EKQ #3

#45 pilot

#165 main

I actually am currently at DVR #3, #45 pilot and #170 main.

Hick agrees on JDs starting point. He also suggested we not use the D tapered needle unless we have stock exhaust and airbox lid on.

Both say start with their suggestion. It will give us the get up and go we've been missing. I just can't find the EKQ anywhere.

Larry, where did you find or order the EKQ needle? Vickery is telling me they can't get it.

Now that I think of it, isn't the BK mod only for the 426's or maybe the 2000 400 and later? I thought the carbs were just different enough for the BK mod to not work for the 99 400s.

Am I crazy? I also think I remember someone posting a similar mod for the 99's. Anyone have more info on this?


Due to the different carbs, the 98/99 WR's require the "KL" mod. And I think Taffy has a mod of his own that also works. Check the archives, there's tons of info.

The "BK" mod is for '00 and newer 400/426's. Also tons of info. on this.

Search for "Taffy mod" it is probably the easiest to do for a 98/99 for the APJ timing and squirt duration.

OK guys thanks for the input. So Doug, we need to find the EKQ needle. Let me know if you have any luck. I'm also interested in doing the "Taffy mod" for the APJ. I'll post under the thread you started about that.

Dougie and Kerry,

I dug through my stuff and found my extra needle jets. Here's the PN's:

OBEKN - 5JG-14916-EN

OBEKP - 5JG-14916-EP

OBEKQ - 5JG-14916-E1

Dont let the fools at the shop tell you that's the wrong part #. Their microfiche is wrong. These three needles are actually still in their Yamaha packaging coded appropriately with the PN's and the correct markings on the needle jets. (I went thru the same headache 3 different times with the folks at the shop before James Dean steered me down the right path...).

I'm actually running an EJQ...which is a Sudco knockoff...and the closest I could get to an EKQ (only 1/2 clip richer). Their brass but do the job just fine...and are cheaper. Another option for you...just get the 1st and 3rd letters correct and adjust for any differences in the 2nd letter by changing your clip position (as long as it's not way off).

In addition, I'm running a smaller pilot jet (the stock 42)...which you might you'll need once you make the change. First, try the EKQ needle with your 45's...and see what you think.

Do the change boys...you wont be disapointed!

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