The latest stupid throttle stop question...

After reading the tech article on the throttle stop removal/shortening, and after riding my 2001 WR426 last week, I believe it may be possible that my WFO sputter may be due to the "complete" removal of the throttle stop. Since it was taken out when I bought my bike, I have no reason to believe that it was shortened and re-installed. My local mechanic who prepped the bike says he removed it. Could this be why Im spitting, (WFO), instead of screaming? As stated in the tech article, "the computer gets confused at full throttle, especially at high rpm where it acts like a rev-limiter making the engine start and stop when it reaches about 9000 rpm".

I have yet to clip the "infamous" grey wire, but am finally getting into the garage on Monday to do it. Thanks for any suggestions.

Yes, that does sound like your problem. With the throttle stop removed the throttle valve opens too far and causes the sputtering effect. I had the same problem when I removed my stop. I went back trimmed it, problem solved.

I can tell you from experience, don't cut the stop using someone elses measurement. I would recommend taking your carb off triming a little at a time until you notice the slide open just to the edge of the Venturi. Not to much, not to little.

Oh, come to think of it if your bike is 01, I think you can simply order the stock 01 YZ stop...

Good Luck!

Mr T

I'd recommend fitting the YZ stop, rather than cutting the WR stop. It will take you five minutes, and be done right. Incidentally, the 2000 YZ stop fits the 2000 WR's, and I think both '99s are compatible too.


'00 WR400F, YZ Timing, FMF Power Core IV2, Renthal Bars.

I got this part # off a previos post.


Its supposed to be the YZ stop, I have not ordered mine yet though.

Thanks guys. I will order the '01 YZ stop today, and report back after its installed.

Thats the part number. Even has a little blob of threadlock already on it...

Anybody know if this will work on the '98 WR as well? Thanks


Yamaha says they dont have a part for that #. I guess it may be cause the bikes are new, they dont have them yet. Im still trying to determine via the manual, and schematic what the correct item is. I'll post again as soon as I have an answer.

I herd the part # was eithrr not on, or hard to find, on the dealers microfisch films. I also herd parts guys were mostly a few knobbies short of a full MX tire. I recall one guy saying hew was told he would have to buy the whole carb if he wanted the part! Did your dealer tell you the pn was no good?

The parts dept. went so far as to fax me the micro-view, and have me tell THEM what part # it was. Hows that for service! At least I get 15% off IF I can figure out the pn......

Anyway, I think I found the screw. I have a pic posted here:

Thanks to z4me, we have determined that this is probably it. Does anyone know the proper amount to shave off the end? It is approx 34mm long, stock.

The correct PN is 5JG-14591-00-00

for the YZ stop. It is 23mm in length, including the head. It is available, that is the right number, I already ordered and received one.

And yes, parts guys are stupid, anybody who knows, more or less, where the stop is located should spot the correct reference # on the fiche in no more than two seconds.

Thanks for the pic Wyano, Mine was gone when I got the bike, I was not sure if it went in from the top or bottom, looks like it comes up through the bottom. Now, how the hell do you fish it in there.

That is certainly it. Cut it down 8 to 10mm then check to see if your slide opens all the way. A little blue Loctite helps keep it in place.


It comes up from underneath. Take the black plastic cover off the right side of the carb, and you should be able to get at it. You might have to slacken the carb and twist it a little.

No, the 01 stop doesn't work for the 99's. Can't comment on the 00's though.

Good Luck

Huhh? I thought they were all the same, even the 250Fs???? Same carb yes / no ?

The 2000/2001 WR/YZ carbs are substantially different than the 98/99's.

Ordered the YZ stop today. This was the part # : 5GS-14591-00-00

I dont know why the number is different from what Hick posted, but I hope its right.

If its not, I guess Im out $11, and I'll just have to shave the original stop down.

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