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Could anything else be causing this

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2 races ago about 1 lap into my harescramble, my bike starting dying at anything under 1/8 throttle. struggled thru the raced, obviously. Got it home and tore it apart to find my System Racing Fuel Screw seemed to have been backing out, looks like the lower o-ring had deteriorated.

So, I put a new o-ring on. Rode at the house some, no noticeable problem.

Got to my next race (yesterday). 2 laps in, it started it again. I havent' torn in to it yet today to see what the fuel screw is looking like.

MY thoughts..This fuel screw is brass and aluminum. I put the new 0-ring on on bottom groove of the brass part. The aluminum part has about 3 grooves in it. Looking at their picture on the website (http://www.systemtechracing.com/category_s/47.htm). Looks like I should have the o-ring on the aluminum part.

so seeing as I've had this bike (05' KTM 450EXC) for about 3yrs now with zero FS problems, I've had the quick adjust fuel screw in for at least 2yrs. I'm guessing this o-ring is my problem.

Is there anything else I should be looking at. I don't want to travel all weekend long to run 2 laps and load back up again:banghead:

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I put the stock back in tonight. I've played with everything from 1 to 4 turns out. I still dont' get a completely clean acceleration on blipping the throttle.

The spring is intact.

the only major thing I know has changed has been the weather has been about 15° warmer the last 2 races, but that wouldn't explain why I haven't had to change it over the last 2 years.

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Let me add this nugget. I adjusted the valves back in December. I put well over 100miles of trail riding on this bike before this problem started up, though.

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