2015 250sx jetting "problems"

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7/17/2017 11:09 AM
Edited Date/Time: 7/17/2017 11:20 AM

Hello Vital, first poster.

I got myself a 2015 250sx in a pretty neglected shape and the jetting was all over the place, not even close to our climate. Anyway I decided to get it jetted and have been lurking in all the threads here.

Climate: Sea level, 15-25 celsius, 50-80% humidity. I know its a big range but getting jetting to "ballpark" its easier to go up/down a notch.

First I jetted according to the factory specs and it worked out pretty good. I had some spooge at the silencer, I bigger ring, not to bad to be honest but if something can be better - why not?

I found the "highest idle" and its about 2-2½ turns out.
40:1 with RON98 in Europe, pump fuel.

I found some "universal jetting" by Digger29 and installed it. 170 main, 40 pilot, NECJ at 4th clip. Spooge went away, sounded "darker" when it revved. Airscrew 2 turns out, idles but doesnt really pick up all the way to the top when I blipp the throttle. Bike bogs slightly under throttle when cold but fine when warm. No spooge.

I got some response on another forum to raise the clip to the 3rd and I did.

The bike died instantly I blipped throttle when cold. When I set the idle "high" when warm it revved out very far when I blipped the throttle but once I lowered the idle it bogged again, not until it died but still - every time. After I let go of the throttle it would also make "tick tick" sounds from the exhaust, like tiny rocks inside it. No spooge.

With both settings I can lug the bike around without any problem

Edit: I have had a main jet getting loose and it would just "blubber" and not going into the powerband so I guess I know how it feels when being waaaay to rich


7/17/2017 2:44 PM

Get the fuel mix back to OEM spec's and then see where your jetting is. I think you will find the OEM jetting will be very close to what you need.

Paw Paw


7/17/2017 5:43 PM

I ran similar set up on our 14 250sx except I was richer on pilot and main but I also went with a ktm150sx carb and a quad flow torque wing