2017 KTM 150SX jetting/upgrades

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4/3/2018 11:54 AM

So I just picked up a new 2017 150sx the other day. I rode it for the first time and I was impressed with the power and the light feeling it had. The jetting was a little rich on the bottom but I think that can be fixed by moving the needle. I've read a ton of different things on jetting and using different carbs. I want to just keep the mikuni carb and get it jetted right. Does anybody have some good jetting recommendations? JD jet kit worth it? Any feedback is appreciated.

Also let me know what are some good mods to do to this bike. I'd like to do a Vforce 4 reed block and a fmf 2.1 silencer. And of course a few other bolt on goodies. Let me know if you have any tips/ tricks about this bike and what else I should do to.

Thanks.

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4/3/2018 12:30 PM

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4/3/2018 12:41 PM

Cant go wrong with what you suggested already. Only tip from me would be to fo your reeds and pipe before you jet. If you jet first youll likely end up being a tad lean after the pipe/reeds and have to rejet for it.

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4/3/2018 12:53 PM

Congrats on the bike!

My jetting was very rich until about half throttle when I got it. I tried a few different options starting with MXA's recommendations as a baseline and moved around from there. FYI I am using 40:1 with motorex premix and 93 octane pump gas. My riding consists of a combination of sand, loam, and dirt. I am an intermediate 25 year old rider, spend my time equally between racing and open practices.

I dropped the Pilot down to a 35 from a 45 stock. I messed with a 32.5 but ran the 35 for a bit of safety and piece of mind. I used the 43-74 needle in the lowest position (clip is at the very TOP of the needle so position 1). Air screw 2.5 turns out. I can't remember for sure but think I dropped to a 460 main from a 470.

Once I found this setting the bike ran so much cleaner. The throttle roll on is crisp off the bottom and after 37 hours I just did my top end and the piston was in great shape, not too lean, not too rich. I was prepared to buy the JD Jet kit if buying the pilot and main jets I mentioned didn't work out, but my bike runs very well, thus I never ended up purchasing it.

When it came time to do a chain and sprocket I added a tooth to the rear (49T sprocket) to make 3rd gear easier to carry with less clutch.

The only other thing i changed was adding a set of Pro Taper Fuzion bars in the SX race bend because I like a crossbar. THis summer I would like to get an FMF Fatty pipe. I am torn between the shorty and powercore 2.1 silencers, I see more people around me running the shorty, maybe someone with experience on both can weigh in.

My stock reeds upon inspection must have been a good batch because they were fine with no gaps, when the time comes i'll get a V-force 4.

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I'm not an actual kid
Red Bud Vet Fest 2020: https://www.youtube.com/watch?v=3gpxS0KgQFc

District 14
2017 KTM 150

R.I.P. Steel City

4/3/2018 2:09 PM

ThatOneKid wrote:

Congrats on the bike!

My jetting was very rich until about half throttle when I got it. I tried a few different options starting with MXA's recommendations as a baseline and moved around from there. FYI I am using 40:1 with motorex premix and 93 octane pump gas. My riding consists of a combination of sand, loam, and dirt. I am an intermediate 25 year old rider, spend my time equally between racing and open practices.

I dropped the Pilot down to a 35 from a 45 stock. I messed with a 32.5 but ran the 35 for a bit of safety and piece of mind. I used the 43-74 needle in the lowest position (clip is at the very TOP of the needle so position 1). Air screw 2.5 turns out. I can't remember for sure but think I dropped to a 460 main from a 470.

Once I found this setting the bike ran so much cleaner. The throttle roll on is crisp off the bottom and after 37 hours I just did my top end and the piston was in great shape, not too lean, not too rich. I was prepared to buy the JD Jet kit if buying the pilot and main jets I mentioned didn't work out, but my bike runs very well, thus I never ended up purchasing it.

When it came time to do a chain and sprocket I added a tooth to the rear (49T sprocket) to make 3rd gear easier to carry with less clutch.

The only other thing i changed was adding a set of Pro Taper Fuzion bars in the SX race bend because I like a crossbar. THis summer I would like to get an FMF Fatty pipe. I am torn between the shorty and powercore 2.1 silencers, I see more people around me running the shorty, maybe someone with experience on both can weigh in.

My stock reeds upon inspection must have been a good batch because they were fine with no gaps, when the time comes i'll get a V-force 4.

Hey thanks for all the input! I will play with the jets a little bit and move the clip to the very top. Most everything I've read, people are saying to put the clip at the very top.

Once I wear out the stock sprockets a bit, I plan on adding a tooth to the rear also.

For the silencer I have the same problem. I'm not sure if I should get the shorty or spend the extra money and get the 2.1. I cant see myself spending the money on the ti 2.1 so I'll probably go with just the stainless.

Also planning to go through the linkage and swingarm bearings to grease everything up well. Typically bikes that come from the factory aren't greased very well.

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4/3/2018 2:11 PM

kb228 wrote:

Cant go wrong with what you suggested already. Only tip from me would be to fo your reeds and pipe before you jet. If you jet first youll likely end up being a tad lean after the pipe/reeds and have to rejet for it.

That's a good point. Thanks.

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4/3/2018 3:03 PM

Make sure you keep a notebook of your settings for different temps and altitudes. Good luck with the new bike and have fun!

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4/3/2018 3:08 PM

I just picked up a new 18 150SX myself and got a JD kit to throw in it. Ive used JD kits on all the Mikunis on my CRs and they made a big difference and were really crisp and responsive. Ill report back on this thread how it runs next time I go to the track.

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4/3/2018 3:21 PM

macz400 wrote:

I just picked up a new 18 150SX myself and got a JD kit to throw in it. Ive used JD kits on all the Mikunis on my CRs and they made a big difference and were really crisp and responsive. Ill report back on this thread how it runs next time I go to the track.

Yeah let me know how it does. If I can't get the stock jetting dialed in just right then I'll probably go with a JD kit also.

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4/3/2018 3:50 PM

Factory fatty works very well on the 150. Vforce doesn't ads any power, but helps with jetting and reliability.

On our 125 we went leaner pilot and needle and richer on the main.

Amazing fun bike to ride

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4/4/2018 5:25 AM

Hi I have a 17 150sx have spent a lot of time setting it up the best place to start with your motor / card set up is the head the squish band needs adjusting and put the F1 moto performance power valve arms in to stop the power valve from jamming. The FMF pipe with powercore 2 or stock muffler work good on the 150 a bit more over rev.the float height in the mikuni is to high from stock that needs to be fixed before you do your jetting I was running a 27.5 Pilot and 460 to 470 maim it’s very hard to get the dogy spot jetted out of the bottom end a BR8ECM plug helped clean it up a bit. I have a PWK 38 airstriker on now one of the best things I have done to the bike don’t waste your time with the mikuni. And put a 47t on

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4/4/2018 5:42 AM

The red , yellow, and green power valve springs from the 250 and 300’s will go in the 125/150 i’m Testing the red spring at the moment

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4/4/2018 6:41 AM

Nap wrote:

Hi I have a 17 150sx have spent a lot of time setting it up the best place to start with your motor / card set up is the head the squish band needs adjusting and put the F1 moto performance power valve arms in to stop the power valve from jamming. The FMF pipe with powercore 2 or stock muffler work good on the 150 a bit more over rev.the float height in the mikuni is to high from stock that needs to be fixed before you do your jetting I was running a 27.5 Pilot and 460 to 470 maim it’s very hard to get the dogy spot jetted out of the bottom end a BR8ECM plug helped clean it up a bit. I have a PWK 38 airstriker on now one of the best things I have done to the bike don’t waste your time with the mikuni. And put a 47t on

Do you lose any bottom going with the powercore 2? I like the idea of more over rev with the powercore but don't want to sacrifice too much bottom to get there. Have you tried the powercore 2.1 at all?

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I'm not an actual kid
Red Bud Vet Fest 2020: https://www.youtube.com/watch?v=3gpxS0KgQFc

District 14
2017 KTM 150

R.I.P. Steel City

4/4/2018 7:15 AM

I have the powercore 2 and stock 150 muffler thay are the same length 13.5 inches long the Fmf is a bit lighter I think the pipe is just making the difference the bottom end felt the same mid to top pulls longer . But the jetting will play a big part in the way it feels to I got the Fmf because the stock pipe got damaged

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