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150sx jetting for fmf

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i just purchased a fmf factory fatty and shorty silencer for my 2014 150x. I also bought the JD jet kit with 2 different needles and a few main jets. I am rebuilding it and putting all this on it for next season and was wounding what jet and needle i should install. i live in wisconsin so I'm about 500-600ft above sea level. 

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i just purchased a fmf factory fatty and shorty silencer for my 2014 150x. I also bought the JD jet kit with 2 different needles and a few main jets. I am rebuilding it and putting all this on it for next season and was wounding what jet and needle i should install. i live in wisconsin so I'm about 500-600ft above sea level.

I agree with the above post. I put a PC setup on my 150 and ran the jetting by the chart in the manual, it was spot on.

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Really? Thanks guys. I just assumed it would be a lot richer than stock.

Yep, really...:)

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Doesn't anybody read anything anymore?  

 

The JD jet kit has VERY explicit instructions on how to jet for altitude and temperature, so I don't understand why the OP is even asking the question.  Just follow the directions, which tell you exactly which jet/needle/clip position to start with, and how to change them to fine tune the jetting.  By the way, James (JD) responds very rapidly via email if you do have any issues.

 

Secondly, if you are using a JD kit, which the post clearly states, no one should be advising the OP to use the ktm jetting specs in the manual unless he is tossing the JD needles.  Every JD needle I have seen (including the one in my KTM) is much thicker than the stock needle, so it needs a much larger main jet to compensate for the needle thickness.  Running the main jet specified in the manual with a JD needle is a recipe for a major top-end meltdown due to super lean conditions.  If you are running JD needles, you need to use main jets in the range his instructions specify.

Edited by rpt50

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I have been emailing back and forth with the company. They recommended a 175 main. 38 pilot. And blue needle with the clip in #4 slot from top. The stock jet is a 180 main. 40 pilot.

So I asked why they have it so lean and they say it's because of how there needle is designed.

After I had my carb all apart and was ready to re jet I open the kit. That's when I discovered that A. The kit does not contain any pilot jets and B. Doesn't even come with a small enough main that they recommend. So I conclude that either JD has no idea what there talking about or I got a junk product. So I have decided to return the kit

Either way I decided to jump it up to a 182 main and leave everything else stock including the needle. The bike is a rocket now but the plug looks slightly lean. I think I will jump up to a 185 and see what I got.

Edited by Jakeshallow27

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I have been emailing back and forth with the company. They recommended a 175 main. 38 pilot. And blue needle with the clip in #4 slot from top. The stock jet is a 180 main. 40 pilot.

So I asked why they have it so lean and they say it's because of how there needle is designed.

After I had my carb all apart and was ready to re jet I open the kit. That's when I discovered that A. The kit does not contain any pilot jets and B. Doesn't even come with a small enough main that they recommend. So I conclude that either JD has no idea what there talking about or I got a junk product. So I have decided to return the kit

Either way I decided to jump it up to a 182 main and leave everything else stock including the needle. The bike is a rocket now but the plug looks slightly lean. I think I will jump up to a 185 and see what I got.

That's interesting. I usually do my own jetting, but when a bike gives me trouble, I have ordered JD kits. Maybe ten years ago I ordered one for a CR Honda and it was awesome. I also ran one in my 09 ktm. But maybe a year ago I ordered one for an RM 125 and had similar issues to what you have described. The instructions referred to a pilot jet size that was not even in the box, and when I emailed they seemed confused about what should have been included. I ended up buying my own jets to get it sorted, and I just figured it was just one bad kit since they worked well in the past. Maybe their quality has really slipped! Edited by rpt50

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That's interesting. I usually do my own jetting, but when a bike gives me trouble, I have ordered JD kits. Maybe ten years ago I ordered one for a CR Honda and it was awesome. I also ran one in my 09 ktm. But maybe a year ago I ordered one for an RM 125 and had similar issues to what you have described. The instructions referred to a pilot jet size that was not even in the box, and when I emailed they seemed confused about what should have been included. I ended up buying my own jets to get it sorted, and I just figured it was just one bad kit since they worked well in the past. Maybe their quality has really slipped!

At least I'm not the only one this has happens to. I was thinking maby I just have terrible luck. Anyone else use JD jet kits and notice a big difference between there needle and the factory one

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i know this is an old post but i just bought a fmf fatty and shorty for my 2014 150sx today and went out to test.

 

Tried with stock jetting first 180 man ,N1EJ 3rd clip, 40 P , 2 turns AS 

 

Seemed crisp and clean but powerband was very narrow with no topend at all! started to think the shorty was a huge mistake. 

 

Then I found a post on ktmtalk from a guy who put the same pipe and silencer on his 2013 150sx and did alot of jetting testing.

 

He ended up with

25 degrees Celsius/sea level to 500ft

 

190 main 

blue jd needle 4th clip 

42 pilot

air screw 1 1/4

 

I had the jd kit so i tried it 

25 degrees Celsius/2200 feet

 

Holy shit it was awesome right from the get go this things a rocket now and it sounds sweat too.

 

I rode a buddies stock 2014 150sx back to back and it was smoother but burbly and not even close to as responsive. 

 

My 150sx now feels explosive like my 05 yz125 but with more everywhere. I  absolutely love the 05-present power-band and have wished my throttle response off the bottom on my 150sx was the same and now it is pretty dam close.

 

Now i just need to get the suspension upto par.

 

$500 a lot for pipe and silencer but it was worth it.

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