1996 KDX 200 Does not run right, help!

check the end of the kips shaft by the govener..

sound more like a fuel problem did you blow out the carb circuits with compressed air.

also from sitting it may have a mouse house in the silencer

you can also put a new filter in if you haven't already they tend to become solid from sitting

Get fresh gas, fresh plugs, clean out the exhaust, and work through jetting it right...

If it were me then, I would go on to the classic "fuel, air, spark" and start trying to figure out which one has gone missing at high RPM. It can get tricky though.

Based on my experience, I would pull and clean the carb again. I can't tell you how many times I have had a carb beyond pristine, put it back in, had running problems, pulled it back out, cleaned it again (sometimes seeing something, sometimes not) and put it back together to then have it run well.

I'd pull and check the petcock and full cap (vent) as well.

I'm starting with "fuel", because that is the part that is pretty much guaranteed to turn to goo and screw with a bike that has been sitting.

But you are groping in a blind room until you find it. The good news is, that on a two stroke, it's not that big a room and pretty soon you will find something...

Do you have a air vent on your fuel cap, does it make the sound of escaping air when you release it?

Remove the petcock and take a look, it could be varnished, I have had some that just needed replacing.