Originally Posted by tomcfitz
I'll try that, but I'm fairly convinced that the idle screw isn't the problem, as i doesn't run correctly even above idle, and it was idling fine, even a little high, and the screw as not been adjusted at all since.
Check for loose cylinder/head nuts. Make sure that the carb is both pushed all the way onto the manifold and tight. Check the spark plug for looseness and fouling.
And when you can, give us some more info such as; pre-mix oil brand/type and ratio, spark plug brand/type, etc.