All 2st Jetting Chat - Need Help? Post Your Questions Here

It only "FINE" tunes the carb off idle. Your pilot jet , slide, and needle are what tunes just off idle. You honestly should get some help with this. It is a bit of a science. You should be able to start with the idle mixture screw at about 1- 1.5 turns out. Screw in and out till you achieve maximium idle speed then reset your idle to correct idle speed of about 1200 rpm.

I had my '02 WR250 jetting pretty well dialed in. Ran good, could feel the bottom to mid, and mid to top. When I first got it, it spooged so bad, that it covered the back of my jersey.

I went with:
380 Main
Stock Needle - raised clip one position
32.5 Pilot

This weekend I decided to toss in the JD kit that I had forever. I mainly was interested to see what the JD needle would do

JD kit recommended:
410 Main
Red Needle - middle position
32.5 Pilot - which I already had in

Installed per directions, but used 400 Main instead.

Rode it Sunday at Brown's camp a little, unfortunately did not get a good feel from the changes.
The temp. was definitely colder. With the changes the idle was way high. Took a bit to remember how to adjust it. One good thing was just a tad bit oil spotting on end silencer tip.

Thanks for your replies...

The needle was set in the middle position. I lowered the needle one position (raised the clip 1), and this seemed eliminate my bog in the mid... Runs MUCH stronger... Wondering if I should try one more just to see the outcome....

Do a plug check. You might not like the outcome if you don't. Can you say "SEIZURE" ?

I will do that, thank you...

I'll throw this out there for the WR250 owners; Don't get misled by the large pilot jet sizes that the 125 and 300 guys are running in their Mikunis. I just edited my post in the 2t data base after going from a 32.5 pilot to a 30. When I think of the guys that have pitched their Mikunis for Keihins probably because the Mikuni circuits overlap a lot and it's easy to adjust the wrong circuit and not get the results. My experience on my 250 is to get a pilot in that will allow the air screw to be ideal at or close to 1 turn out. If you have to go out close to 2 turns or raise the slide to get enough air to idle you are affecting the needle and it's ability to properly meter the mid then you adjust the needle which affects the upper end into the main and you're chasing your tail. I was happy with my jetting with the 32.5 pilot but bought a 30 pilot just to see what it would do, after switching to the 30 the bike will idle as long as you like in gear or neutral, is a matter of fact yesterday I stopped with my bike idling put it on the kickstand and picked up a pocket full of golf balls got back on the bike and cruised away without a hint of the plug trying to load up. (I live next to a golf course and there is always golf balls appearing in my practice area.) It idled good before but not good enough to get away with that.

+1 with the 30 pilot. I have also had the same results.

Thanks for that info
I have always wanted to try a 30 pilot. Probably even less spooge. May have to get from online jet place, local dealer said 32.5 was the smallest they had

My local dealer (independent shop) had all the way to 27.5, so tell your dealer to order it.

Will do, thanks

I got my 30 pilot from Halls in Springfield.

Thanks lankydoug

hello! I use my red JD needle in the leanest clip pos. down to 50F at sealevel. Runs perfect with that and a 40 or 42 pilot and 175 main. Keihin PWK that is.

Johnny

Thanks for the reply... Like Vinduro recomended, I'm gonna do a plug check tonight, and adjust, or leave as is from there... Haven't ridden in almost 2 weeks ! Get to ride 2 of the next 3 days tho!!

I have been running a 38mm PWK Airstriker (Screw cap) in my 1996 WR125 & have the following jetting.

Main - 180
Pilot - 40
Slide - 7
Needle - NOZI - 2nd from top
A/S - 1.5 turns out
Fuel - 40:1
Sea level to 500 mtr
Dynoport pipe & muffler

It runs good from bottom & pulls hard in the midrange & screams up top. I was hoping to gain a little more from off the bottom.
I am looking at installing a 36mm PWK Airstriker (Screw cap) to help this but I am unsure of the jetting that is required for the smaller carb.
I have 3 questions ;
1.What jets should I run in the smaller carb? Richer or leaner?
2.Can any one tell me the float height of the later model PWK carbs. The ones with the 2 screws on top & the TPS on them. Not the screw cap PWK's.
3.Is there a noticable difference in performance between the screw cap PWK A/S & the Newer style PWK A/S (TPS)
Any help would be appreciated.

Check out my specs in Jetting. Mine is a 2011 WR150 and the carb is a 36mm PWK Airstriker (KTM).

I cannot give the jetting for the latests PWK style carb! but I have been trying a 36mm and a 39mm on two different bikes
The 36 is so far proving to be the better choice for tight going but still retains just about the same top end, on flat out tests the 39 gives a top end of 76mph the 36 gives 74mph over a measured distance so not a lot in it
The 36 pulls through the range much cleaner/smoothly gives far more fuel range and goes a long way to cure the phantom midrange bog
main 175
slide 5.5
needle nozi (I think as I have tried many)
pilot 45 as its cold here but could go a tad leaner
Not sure if this is of any help but I fitted carb dividers to the inlet side (home made) to both carbs and they made a big difference at all low throttle situations and pulled far harder than stock

Thanks guy's for your help,
I swapped the 38 for the 36 today & jetted it like this
main - 180
pilot - 38
Slide #6
Needle - NOZH-4
A/S - 1.0
Fuel - 40:1
temp - 32'C /85 % humidity

The bike started first kick, it was a bit rich to start with & was smoking & spooging a bit & a little bludder just off the bottom. Once into the mid it started to pull well, smoother than the 38mm PWK (Screw cap). When the main/needle kicked in she started to bog again. Once into 4th gear the bog seemed less, clicking 5th was a little better, 6th was about the same & feeling fat, then the bike started to foul the plug & I backed off until it cleared & the bike improved.
I wound out the Air Screw another half turn to 1.5 & that cleaned up the bottom end bog with less smoke at idle & crisper but I ran out of light to continue testing. I pulled the plug & it was wet & black. So I'm thinking I'm maybe too rich on the main or the float level is too high.

Dwight, I noticed you are running the same main in the 38 & 36 so I thought I'd do the same in mine but I think it is too rich for the 36 especially with the high temps & humidity we have here at the moment. What float level are you running in the 36?
I might go down to a 178 or 175 main & do a plug chop tommorrow to see how the main is running.
Was the 38mm PWK an older screw cap style or a newer one like the 36mm(TPS) you have on?

I was using the original 1996 WR125 airbox rubber & a modded 1998 WR125 inlet manifold together with an 08 VForce3 reed block for the 38mm PWK (Screw cap) Carby. I had to install an airbox rubber from a 1999 WR 250 to gain the length for the shorter 36mm PWK(TPS) carby(16mm shorter), this also allowed me to run the standard manifold for the 08 VForce 3 reed block.
Now it lines up the inlet tract a lot straighter between the airbox & reeds, not so many turns for the air to get around now.
One drawback is the carby is now tilted forward from level a fair bit now. I wonder if this is causing the high float level/rich condition? I set it so the valve closed when the float was level with the base of the carby.

I'd love to try a newer style 38mm PWK on it & compare the two newer style carb's, when I can get my hands on one!

I am running a 175 main in my 36mm. 35 pilot. A/S - 2 turns out. Needle NOZH -#3. 6 slide.
12mm on float. I suggest about 14mm. Someone pointed out that 16-18 was norm. Mine was much lower originally.

Would a richer slide give a bit more fuel in the middle or mainly just the bottom third? Currently I have a 30 pilot with the chy16-61 needle in the third clip. Last ride it got around 44 degrees and there was a bit of a hole in the middle that had not been there before in warmer temps. It just made it harder to pull onto the pipe. I might try putting a half clip spacer for the needle but I also thoght of trying the #4 slide (I have the 5 now). I have to be careful though as the bottom end gets rich easy. The 30 pilot was super rich and the NW gathering when it was in the 60s. It felt real good on the very bottom yesterday so I am wondering how much a richer slide will change the bottom end.