Screw both H & L fully in, then 2 full turns out will give you an approx factory setting.
From there start her up, throttle fully open turn the H screw clockwise until she is revving at max then give her about 1/8th turn more, this will drop the revs slighty but give you better torque when it hits the green stuff.
L adjustment, easy, just move the screw until its going hard again, then it will be a case of moving the idle screw so the head isnt spinning.
This should give you a a fairly decent set up moving from idle to max without any bogging.
Hope Ive not confused you.
Andy
PS if your machine still has the plastic caps on the H and L screws cut them off, they are only there for fuel emission standards when it left the factory, they are more of a nuisance then anything and no real carb adjustment can take place with them on. Removing them should not effect warranty, however if the machine is still new then double check.
andy, May 2009