KTM 250SX Keihin PWK 36 Jetting?

YZed250
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YZed250
Anyone have a baseline jetting specs for running a Keihin carb on the new KTM 250cc motor?
I'm running a stock engine with a pipe and around sea level and 100ll/91Oct mix, 50:1.
I heard the new 250 motor needs more fuel than the 2016 and older 250SX, FWIW.
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paddyB745
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paddyB745 1/17/2019 6:23pm
1/17/2019 6:23pm
Im running the 38 PWK air striker on my 17 TC250. Similar conditions. My settings now are 42 pilot, NECJ needle 3rd clip, 175 main. Also, decked the head and set the squish to .045” and it’s night and day better than stock.
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YZed250
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YZed250 1/18/2019 9:46am
1/18/2019 9:46am
paddyB745 wrote:
Im running the 38 PWK air striker on my 17 TC250. Similar conditions. My settings now are 42 pilot, NECJ needle 3rd clip, 175 main. Also...
Im running the 38 PWK air striker on my 17 TC250. Similar conditions. My settings now are 42 pilot, NECJ needle 3rd clip, 175 main. Also, decked the head and set the squish to .045” and it’s night and day better than stock.
Does it still have a hit? I love the stock power during the SoCal winter, but find myself unplugging the wire as tracks get hard or if I am on the trail.
paddyB745
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paddyB745 1/18/2019 10:03am
1/18/2019 10:03am
YZed250 wrote:
Does it still have a hit? I love the stock power during the SoCal winter, but find myself unplugging the wire as tracks get hard or...
Does it still have a hit? I love the stock power during the SoCal winter, but find myself unplugging the wire as tracks get hard or if I am on the trail.
Power is very smooth, not a huge hit and it’s super easy to ride. You can easily adjust that as well with the power valve spring. I ride a lot of off-road and motocross and the motor works great for both.
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Greenbush
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Greenbush 4/27/2021 3:18pm
4/27/2021 3:18pm
Just happened upon this post cuz I’m wondering the same.
I’m running a 185 main 48 pilot and the NE1i needle in the 2nd from the top at around 60-70 degrees seems pretty good but I feel the needle is too lean but I change the clip position and its definitely too rich I’m about 1000 feet. Curios if anybody had a better needle recommendation or jetting recommendation in general.
Cammy41
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Cammy41 5/25/2021 12:31pm
5/25/2021 12:31pm Edited Date/Time 5/25/2021 12:31pm
Im running the pwk36 on my 19 sx250
Sea level
Pro circuit system
Boyesen rad valve
38 pilot
Necj needle
3rd clip
165 main
Bart149
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Bart149 11/15/2022 8:37am
11/15/2022 8:37am
I have a 2019 and just bought a PWK36. Anyone using the NECW needle? It looks like it is a little richer?
Bart149
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Bart149 11/15/2022 8:45am
11/15/2022 8:45am
How about the power jet mine has a 85?
digger
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digger 11/15/2022 2:16pm
11/15/2022 2:16pm
Bart149 wrote:
I have a 2019 and just bought a PWK36. Anyone using the NECW needle? It looks like it is a little richer?
That NECW needle should work just fine, It’s 1 diameter size smaller/ richer. On the 250’s I sometimes like it
more the the J starting diameter.
The 85 jet your referencing, I believe,is the starting jet, and shouldn’t be messed with.
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mxstate
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mxstate 11/15/2022 2:30pm
11/15/2022 2:30pm
There's another thread on this somewhere , haven't searched for my reply
22 MC 250 GasGas
36 mm PWK, 38 pilot/165 main/NECW #3 . Bike runs very clean, smooth (as smooth a 250 2 stroke can be !)
I have a flywheel weight, and with little patience found the sweet spot for the PV adjustment once I got the jettgin to my liking.
For some time I ran the TMX and used AJ's spec and was able to go up to rather large main jet but does not feel the need with the Keihin
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Bart149
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Bart149 11/16/2022 5:34am
11/16/2022 5:34am
Thanks, I am going to give the NECW needle a try. What's your air screw at 2 turns out? I am currently running AJ's jetting. but I am tired of it pissing gas out every time you tip the bike a little. Have the same problems with the 125's we have.
mxstate
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mxstate 11/16/2022 7:02am
11/16/2022 7:02am
Bart149 wrote:
Thanks, I am going to give the NECW needle a try. What's your air screw at 2 turns out? I am currently running AJ's jetting. but...
Thanks, I am going to give the NECW needle a try. What's your air screw at 2 turns out? I am currently running AJ's jetting. but I am tired of it pissing gas out every time you tip the bike a little. Have the same problems with the 125's we have.
a/s adjustment is something you need to fine tune. I set mine at 1.5 to start, got the engine at operating temps
Next I hold the throttle a steady rpms above idle , while opening/closing the screw to find the highest rpm point.
I'm about 1 3/4 now .

digger
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digger 11/16/2022 12:34pm
11/16/2022 12:34pm
Bart149 wrote:
Thanks, I am going to give the NECW needle a try. What's your air screw at 2 turns out? I am currently running AJ's jetting. but...
Thanks, I am going to give the NECW needle a try. What's your air screw at 2 turns out? I am currently running AJ's jetting. but I am tired of it pissing gas out every time you tip the bike a little. Have the same problems with the 125's we have.
Start out with the air screw at 1.5 turns out and adjust from there.

As far as the gas leaking out when tipped over, make sure the float is set at between 7-8mm, also loop the the vent hose out of the float bowl, and hold the hose looped with a zip-ty. I do that on all of my bikes.
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Bart149
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Bart149 11/28/2022 6:07am
11/28/2022 6:07am
I live up north so it's pretty cold out. I went with a 168 Main, 42 Pilot and NECW Needle. All I have to say is WOW! It's a totally different bike. It Runs Great and started right up and no cold weather bog. With the mikuni I was mixing the gas/oil at 55:1. What mix should I use now 50:1 or 40:1?
digger
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digger 11/28/2022 8:57am
11/28/2022 8:57am
Bart149 wrote:
I live up north so it's pretty cold out. I went with a 168 Main, 42 Pilot and NECW Needle. All I have to say is...
I live up north so it's pretty cold out. I went with a 168 Main, 42 Pilot and NECW Needle. All I have to say is WOW! It's a totally different bike. It Runs Great and started right up and no cold weather bog. With the mikuni I was mixing the gas/oil at 55:1. What mix should I use now 50:1 or 40:1?
If you plan on riding that bike, throughout the winter in WI, I think that main is a little lean. I would feel more comfortable recommending a 172 as your starting point. You'll probably be using a 168-165 during the spring/summer, but everything else looks pretty OK, but that W starting diameter is right on the edge, if you start getting a hanging idle, you're going to need to richen up the needle.
Bart149
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Bart149 11/28/2022 9:12am
11/28/2022 9:12am
Ok Thanks. I will try a 172 or 175 see how it runs. It idled just fine this weekend, but it was kind warm out. What Mix ratio do you recommend? I will have to order the main jets should I try a larger pilot or needle?
digger
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digger 11/28/2022 9:25am
11/28/2022 9:25am Edited Date/Time 11/28/2022 9:26am
Bart149 wrote:
Ok Thanks. I will try a 172 or 175 see how it runs. It idled just fine this weekend, but it was kind warm out. What...
Ok Thanks. I will try a 172 or 175 see how it runs. It idled just fine this weekend, but it was kind warm out. What Mix ratio do you recommend? I will have to order the main jets should I try a larger pilot or needle?
The pilot looks good, but if you're ordering jets, it certainly wouldn't hurt to have the next sizes around what you have in there now. It would not hurt to have the next richer starting diameter in that series needle as well, which would be an NECH, or possibly even the G starting diameter as well. It's always good to have tuning options.

I use 16oz of oil to 5 gals of fuel for every bike I own, which is a 40:1 ratio. NEVER change the fuel : Oil ration to correct a jetting issue.
luke11
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luke11 11/29/2022 11:12am
11/29/2022 11:12am
Bart149 wrote:
Ok Thanks. I will try a 172 or 175 see how it runs. It idled just fine this weekend, but it was kind warm out. What...
Ok Thanks. I will try a 172 or 175 see how it runs. It idled just fine this weekend, but it was kind warm out. What Mix ratio do you recommend? I will have to order the main jets should I try a larger pilot or needle?
digger wrote:
The pilot looks good, but if you're ordering jets, it certainly wouldn't hurt to have the next sizes around what you have in there now. It...
The pilot looks good, but if you're ordering jets, it certainly wouldn't hurt to have the next sizes around what you have in there now. It would not hurt to have the next richer starting diameter in that series needle as well, which would be an NECH, or possibly even the G starting diameter as well. It's always good to have tuning options.

I use 16oz of oil to 5 gals of fuel for every bike I own, which is a 40:1 ratio. NEVER change the fuel : Oil ration to correct a jetting issue.

Thanks for that vote of confidence. I’m currently trying to jet a bike for the first time in my life and just bought manual stock jets and needle and each size either side. 
I’ve set it up as per stock settings and am going to go from there. She ran nice in the garage but we will see when I open it up.

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