EKP Needle?????????

I wish DRbillZ were around to answer this. I bet he knows something about this needle. He was the one that told everyone how to fix that off-idle bog.....turn your fuel screw out one more turn.

When it's cold outside? Or when the bike is cold?Sounds like you're saying that you have an off-idle bog AND it's idling rough/wanting to stall while trying to warm up. Is this correct? Don't think about an EKP needle at this point. You need to make it run on the idle circuit first(idle-approx 1/8 throttle). Sounds like it's starving for fuel down there. With the colder weather, it takes more fuel to start because the air is more dense and the fuel doesn't atomize as well. You got your airbox restrictor removed? What is your current jetting? You can search the archives too.

pilot jet?

fuel screw turns?

main jet?


Pilot jet and fuel screw, write stuff down so you know where yo're at and what you have done. With that pipe you should be running at least a #48 pilot jet. Start there. What altitude and temp.?

[ December 29, 2001: Message edited by: Hotler ]

After you fix the slow jet and fuel screw problem you still will benefit from a faster taper needle and way bigger main jet. EKP works for others it should work for you with that exhaust setup. Look at the jetting survey and pick out your riding conditions like altitude and temp and go from there but also consider the 01 YZ426 STOCK ( OBEJ'P) OR OPTION NEEDLE( EKP).

The stock is yamaha PN 5JG-14916-JP-00. The option is 5JG-14916-EP.

Ballistic member 2553 seems to have the hot setup including the 100 air jet, for his area. Check out his thread.

I have the stock but modified muffler and use the OBEJ'P needle with 160 main 48 slow and it really woke up the off idle and mid range. I have the new option (ekp)needle and 100 air jet now and hope to try ot out next week. It may be too much for my exhaust system but probably not for the Yosh unless you are at altitude.

I have a 2001 DRZ 400 with full Yosh pipe and bike runs strong (except off idle bog and cough/ stall while idiling when cold). Would the EKP needle benefit me? What could I expect?

Altitude is 1000' - 5000' and temp is between 45 - 80 degrees. Jetting is 48 pilot and 160 main, the clip is in the middle position. Bike seems to cough worse when I open fuel screw. Fuel screw is open 1 turn out and airbox lid removed. When I hold throttle steady at about 1/8 open, this is when it coughes and stalls most often. Any ideas??????

You may have already done this: Warn the bike up; at idle, turn the fuel screw in until it almost dies, (1/8 turn out?). Then, turn the the fuel screw out and the rpm's should increase, and keep turning until they decrease again. Note where the highest rpm's are and set it there. You should be somewhere between 1 and 3 turns out. If you not within this range, the slow jet is wrong. However since you are coughing at 1/8 turn on the throttle, this is when the needle is starting starting to take over, my guess is that you need to raise the needle a clip or two.

If the bike has been sitting around for a while (3 or so weeks), the jets can get gummed up and will cause the condition that you are having. This just happened on my XR.

By the way, I put in an EKP a few weeks ago and thought it was the best improvement I could have made.

[ December 31, 2001: Message edited by: Jim65 ]


Have you removed the coast enricher device? It's the little diaphram thing on the left of the carb that's always in the way. When I first removed mine I followed a photo posted on the board showing BOTH of the carb connections capped off. My bike did similiar off idle hesitation you describe. One of the capped things is an air jet. This needs to remain OPEN.

I ran a rubber hose up out of the way. This really helped idle, starting and off idle response. YMMV.

I ride from about 500 ft to 5000ft.

155 main

48 pilot

stock air jet

needle clip one up from bottom

2 1/2 turns out of fuel screw

Air box top removed

Stock pipe drilled out (8 holes in first baffle)

I just spent four straight days in the Mojave

riding at around 2 to 3,000 feet. Did full throttle plug checks and all looks really good.

Good power everywhere compared to stock,still

fairly good fuel economy (an issue in the desert with the stock tank) Bike starts well hot or cold, idles well and is pretty responsive right off the bottom at low RPM's.

Good luck, and thanks to everyone else for all the great tips.


CITY BIKE San Francisco

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