This is taken from the evo manual, also here is a link to manual
http://www.horizonhobby.com/ProdInfo...inesManual.pdf

Low- Speed SetRight Needle Valve Correction
Should the low- speed SetRight needle valve
need to be adjusted outside the factory-
established parameters, follow these steps:
A. Loosen the setscrew found on the ring of
the SetRight assembly to which the
adjustment bar is attached.

B. Rotate the needle valve itself (small
slot- headed screw inside the blue ring of
the SetRight assembly) clockwise to lean the mixture or counter clockwise
the mixture as desired.

C. Retighten the setscrew on the ring of
the SetRight assembly and you have
re- established a new range of motion.