Need Info on 99 KTM 250 SX!!!


Jun 5, 2001
I'm lookin at pickin up a 99 KTM 250 SX from a kid I work with that has about 3 hours on it as a temporary ride until I decide on a perminant ride. (I think he rode it up and down the street a few times and it scares him to think about putting it in the dirt!) Will be mostly riding in the desert, goat trail, and some woods. I'm quite aware the bike is all about motocross and big jumps, but it will do the job nicely till I settle into my next ride. Looking for some insight on jetting quarks, ie. settings, comments on the bike in general. Any comments would be appreciated. Thanks!!
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Jul 21, 1999
Here are the jetting specs I finally settled on for my 99 250 E/XC. This will be different from the SX in that the SX doesn't have the spark arrestor. Should be close, though.

45 pilot @ 1.5 turns out on the air screw

170-172 main jet

NOZH (KTM needle) needle in the 2nd leanest clip (2nd from the top)

Stock slide

This is running at about 1000' most of the time. Summer temps. Pump 92
premium at 40:1 with yamalube 2R. It ran well for me with no spooge on both
the stock exhaust setup and a full FMF setup (M21 or M29 pipes w/TCII).

You may still get some spooge depending on your premix. One of my riding
buddies has the exact same bike and doesn't like Y2R so he tried a bunch
of other 2 stroke oils. They all spooged with this jetting anywhere from
not bad to really bad. He finally went to Y2R and it cleaned it up. His
bike still ran well with this jetting and was not fouling plugs just more spooge.

With the cooler temps in the fall in the upper midwest I go to the middle clip on the needle to richen it up just a bit.

Suspension Clickers: (remember the SX has different springs and valving then the MXC/EXC)
Fork comp = 11 out
Fork reb = 11 out
Shock comp = full soft
Shock rebound = 8 out

Dynamic sag is 100mm
Static sag is 25mm
Stock springs

Modifications: Scotts SS; applied 3x clamps; Aloop Pacemaker 3 enduro
computer; Holeshot billet hyd clutch lever w/needle bearings; shorty
front brake lever; Tag and protaper bars; Moose alum hand guards;
braided steel hyd clutch line; all 3 FMF pipes; FMF Turbine Core II;
SRC 3x clamp barkbuster inner mounts; Acerbis fork and front rotor
guards; moose super tubes; Steahly offroad bash plate; Scott's
billet sharkfin; KTM solid rear rotor; Dunlopad Pro-mx rear pads;
EE and IMS Proseries footpegs; EE hyd clutch slave protector; EE rear wheel spacers; delta v-force reeds (dropped the pilot 1 after install); MSR taller, softer seat foam and seat cover; Kstyle shroud and airbox graphics; FMF swingarm graphics; clean, no spooge jetting; EE shock revalve; Flatland
Racing pipe guard; fork boots; DeVol radiator guards.

This bike was stone reliable for me. NOTHING ever went wrong with it that wasn't rider/tree/ground induced. :) I raced it for 1.5 years in enduro's and hare scrambles.
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Jun 25, 2000
I've had a '99 KTM 250 SX since late 1998. I've used it for MX and off-road. I know quite abit about the bike since I've had it for the last three years !
If you want to email me at : I'll be glad to relay everything I know.

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