LarryCO jetting EKP


I got a chance to test out the jetting with the EKP needle. It is awesome! I tested it at 8000 feet and there is absolutley no bog, no backfiring and no hesitation. The bike pulls in all ranges without any problems. My new settings are in my signiture.

Wicked Crash,

What needle clip position and main are you running with at 8,000 feet.

Way cool amigo! Glad you like it!

Suggestion for ya...try clip position #3 and go up slightly on the MJ (say 155). Might run even better for ya, especially now when it's cooler. Should improve that midrange and top end even more...

In the summer (below 10K ft), I've been running a 150MJ and clip position #3 on that EKP...above 10K and I switch to the EKQ. See my sig for specifics...

Now all I need to do is to find some time to come ride with you... LOL




I'm running it at #2 clip position and 148 Main Jet (see signiture).

I was trying my summer jetting done at Texas Creek this past weekend (6400 ft) and the main jetting was perfect. But, the bike was hard to start and the bike would have a hanging idle issue. It would rip once I got off that pilot circuit. And ideas on what I could try? I did open up the fuel screw to about 2 1/2 turns, but was afraid to open it up more, thought I might lose the screw. I was thinking of increasing the pilot from a 38/60 to a 40/72 but move the needle down one more position. But I'm already at the second clip position.



It sounds like you are on the right track. Do you have the PAS at 60 (in your post) or 65 (in your signiture)? If the PAS is at 60, I would go to a 65 and leave the PJ at 38. If it is at 65 then I would richen up the pilot jet to a 40 and leave the PAS at 65 and see how that works. It definatly sounds like you are a bit lean on the pilot circuit.

I was down at Texas Creek on Saturday with my dad. We had to leave a little early though since the radiator hose somehow got cut on his KLX. Were you there with the group with the two tone green Dodge?

The PAS was set at 60. Just looking for a good setting so it's not so touchy.

Yes, that was us down there with the big red flat bed with the green dodge. What did you think of the area? Not the best area I have been riding in, but I think it's still better than riding Pueblo with all the junk people have been dropping out in the fields. There were alot of people down there that day, wasn't sure who anybody was.


I find the bikes hard to start at elevation with a 38. I have a 42 and I never have trouble starting, I use this setup from Pueblo to the top of the Continental Divide. Seems to work well in combination with other jets.

I like Texas Creek a lot better than Pueblo to play around. Most of the time though, I will turn south at Texas Creek and continue on to Rainbow Trail. The parking lot at Texas Creek was full, but we didn't run across many other riders. I wondered where they were all riding.

I'll have to agree with you on the hard starting. I felt it was WAY too lean.. I always had to use the hot start knob just to get it running. Another thought, since my bike is a 98, could Yamaha have changed the CDI mapping in later years? I have tried a 40 and a 42 pilot before with a small adjustment on the PAS. The bike started great, but just ran like crap down lower. Seemed to really have no throttle response, just pure bog... I did try different clip position. Could the needle be effecting the pilot circuit, I thought it couldn't????


The only bog I experience is right after idle to like 1/16-32 throttle, I haven't done the BK mod yet, so I attribute the bog to this. It isn't even enough of a problem to do the mod. I an in no way a jetting Jedi, but the setup in my sig has been working very well for me. This if for MX and trails.

Doesnt the Hot Start knob lean the mixture out ie. provide more air ...... ?

I would have thought this would indicate a rich condition if you had to use the hotstart lever to start ...

Do you mean the choke knob? Like Kiwi said, the hot start knob when pulled provides for a leaner mixture. If you have to pull the hot start knob every time to start it even when cold, I would guess that the pilot circuit is way too rich. I know that this is different than what I said before, but if you have to start it with the hot start button when it's cold, I don't think it's too lean. I'm not sure what all was changed between 98 and 02, I thought Yamaha switched carbs somewhere in there but maybe not. The needle should have little to no effect on the pilot circuit. You might want to completely clean the carb if you haven't already, clogged passages in the carb might be causing trouble.

Running a 38PJ/65PAJ with a __P needle causes me absolutely no fits during starting...and that's using the stock '01 starter jet (whatever # that is). I DO know that some folks were talking about leaning out the starter jet to assist with starting, but I've found that I dont need this.

If you're running a 38PJ/60PAJ, you're probably too rich using that P needle. Try a 65PAJ...or better yet, buy an adjustable pilot air screw from Sudco...and you can adjust it until it's right for you.

I believe that the needle DOES impact the pilot circuit, but only on startup/idle. It's the diameter of the needle (__P, etc.) that affects the pilot circuit. But again, given what you've described, you're too rich using a 60PAJ with that 38PJ and EKP...try a 65PAJ and go from there. Dont give up on the 38PJ...I've tested quite a bit and have found it to be MUCH BETTER than running say a 42PJ/75PAJ (stock on a '01).

My $0.02...

Good luck boys! And may the snow's melt soon!


Yes, it was the Hot start knob, not the choke. It's just funny, I know the hot start ciruit should inject air directly into the cylinder to lean out the mixture in case of dumping the bike, but that's the only way that it would start. But from the hanging idle condition, that would mean the pilot ciruit is way too lean..

Also, I have the adjustable pilot Air screw, that's what I was calling the PAS. If I increase from a 60 to 65 on the PAS, wouldn't that allow more air in the mixture and leanout the pilot even worse? I wish I new of a place on the web were I can get a degree on carb theory and jetting mystisism :)...

Could the YZ timing that I have done, changed any other setting that are needed? Just shooting in the dark here.

Thanks guys for all your help,


I just removed the carb and verified that the PJ/PAS was a 38/65. Also removed the plug, this was jet black indicating a rich condition. This would explain the need to lean the carb with the Hot Start button. But it doesn't explain the extremely high idle condition that couldn't be controlled with the fuel screw.


Just noticed something with your jetting. Perhaps that Vortip you've got on the end of your pipe is causing the that, the jetting tests I've done were all with a stock, uncorked exhaust (no Vortip...although, I think I'd like one someday to quiet the beast down a bit).

When you say you have a hanging idle, that means it's too lean to me and you'd want to turn out your fuel screw a bit to compensate (up to 2/5 turns out max). Although, if the ONLY way you can start your bike (hot or cold) is via hotstart, then that would tell me that your bike is too rich on the pilot circuit. Dont know what to say here, other than perhaps trying to yank off the vortip and seeing what that does. If your bike starts to run/start better with the 38/65/EKP, that's some more info to pass along to someone that may have the solution for ya. Also, if you turn the fuel screw all the way in, does your bike stall? It should. I'd also want to verify the number of turns out from fully seated that your PAS is set at. Perhaps you have the wrong # of turns out to equate to a 65PAJ...I cant remember offhand what a 65PAJ equates too...have it written down at home...might do a search online in TT to verify...

I'm putting more stock in the "cant start my bike even cold without the hotstart" description and am betting that you're too rich with that Vortip...and assuming all else checks out (listed above), I'd try a 38PJ/70PAS and go from there. If you try these suggested tests and dont resolve the problem, I'd post the issue under separate cover to make sure the "super guru's" see it...

Let me know how it turns out..


"I've tested quite a bit and have found it to be MUCH BETTER than running say a 42PJ/75PAJ (stock on a '01)"

Larry, man you must be picky, :), because I can't see how it could run any better? Starts first kick 99% of the time and I have little to no bog or hesitation 0-1/4 throttle. What do you mean by runs better? Thanks for the clarification.

PS. I have an aftermarket pipe.


You might be on to something here. When you remove that airbox lid and the baffle, you create a lean condition because more air is flowing thought the system. By introducing the Vortip into the equation, I richend the system again. I should be able to move from a 65 to a 70/75 on the PAS to compensate the the Vortip. I'll try it when I get home tonight. I would expect other people will have the same issue if they try your jetting if they purchase the new Yamaha insert from Gyr-t.

Thanks Again, I'll report back the findings later on, so if somebody else has the same issues, they'll hopefully find some answers in a TT search of the forum.



By "better", I mean that the bike feels more responsive (i.e. snappier) when blipping the throttle. I like this better than the "other camp" that believes in larger PJ/PAJ's. Seems to work better for me when trail riding and wanting to loft the front to clear rocks, logs, your friend who crashed in front of you, etc. Just a personal preference I suppose...


I admittedly have no experience in jetting changes required to support aftermarket pipes (i.e. your Vortip). I've only had an uncorked stock exhaust and have been too poor to go buy a different (quieter) pipe. So let me know how it turns when I finally get my wife to stop buying pets and same some coin, I'll be getting one myself! :)

Good luck


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