Hesitation in Lower RPM after rebuild


Apr 17, 2002
I own a 1994 KDX 200 and absolutly love it. My son recently bought a 1985 XR 200 (I should have bought him a kdx 200). It smoked, but ran good. I just put it together after replacing the rings, valves and Manifold (cracked). I adjusted the valves and bought a new air filter for it. It runs great from about 500 rpms to the top, but has a real bad hesitation from idle to 500 rpms. The hesitation get's better if I turn the airscrew out, but it is still there after over 4 turns out. ( I was told it should be 1.5 - 2 turns out). I remember the airscrew controls from idle to low rpms, but couldn't remember where the needle valve with clip, pilot or main jet control in the RPMs. With the needle valve, should I move the clip from 3rd to say 1st position to make it lean. I also have a fresh sparkplug and gas. Being that the airscrew has to be turned out over 4 turns to run sort of OK at lower rpms I would think it is runnig too lean. I need to check the sparkplug. I also think the person before me who owned it made some adjustments to the carb to keep it running with all the problems it had with bad rings and valves. :(


Aug 31, 2006
I believe that's backwards. Turning the air screw OUT leans the mix. I didn't think they had any further effect beyond 2 turns out. Maybe you're unseating the thing? Anyway IF it's a pilot jet issue, I think it would be a leaner jet thats needed. (if I'm mistaken, someone will let us know I'm sure!)

John Harris

Apr 15, 2002
I am confused, are we talking about the kdx or the xr? If we are discussing the xr, this is the wrong forum and if I remember correctly (not absolute at my age) 4 stroke carbs work differently from 2 stroke carbs and the "air" screw on a 4 stroke actually regulates the fuel rather than the air. In either case you are out of adjustment range and pilot jetting inside the carb needs to be changed. Cheers John
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