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2002 KTM 125sx Engine Tuning Problem

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Hello all...

I have a 2002 ktm 125sx. I am having a carburetor/ignition problem I am hoping someone can help me out with. The bike develops a stutter/sputter/intermittent misfire at 1/4 - 1/2 throttle when accelerating gradually or holding throttle in this range. It disappears when under load, going uphill, or accelerating aggressively. The bike is basically stock except for a Turbine Core 2 silencer.  I have jetted and adjusted the carb (including the float level) for my elevation (5280ft) and temperature as per the service manual (5000-7500ft, 61-78 deg. F), fuel mix 50:1 @ 98 oct. The spark plug looks perfect (light chocolate brown), and have great compression numbers. I just got this bike and this problem was present when I got it so I went through the top end and cleaned/adjusted everything to spec (control flap side clearance, piston ring end gap, dimensions x=0mm and z=43mm, etc.) I changed out the spark plug with 2 new plugs with no effect and have tried a few different float levels,  and although after doing all this, the problem cleared up a little bit, but VERY VERY minimally. The spark plug socket has a little bit of wear but fits snug, the cable shows 0.2 ohms resistance and is screwed in tight at both ends with good connection. So... Where to look next? Reeds? The reeds look to be ok but have only looked at them with the reed block still mounted to the engine. Stator? All the electrical connections are good but have yet to pull there cover and rotor to look at the stator. Coil? Ignition module? Muffler bearings? Blinker fluid? I am kinda at a loss at the moment. My mechanical background is pretty extensive... Bachelors degree in mechanical engineering, MMI grad, KTM lead mechanic at a dealer for 3 years, etc., although I haven't turned a wrench on a motorcycle for about 4 or 5 years now and am a little rusty and have forgotten most everything I knew about 2 strokes. I use to own this exact same year and model bike about a 10 years ago, and I never had ANY tuning problems like this one. Could use a fresh perspective with this one... Thanks.

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two things come to mind.

Jetting-ALL KTM 2st have a too rich rich needle on the bottom causing surging into the mid range and low end sputter. Need to change the needle to cure this.

PV control arm wear-the control arm wears out and the PV floats while trying to rev-see explanation of this in FAQ tips at top of first page for 2st.

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