I have a 2005 CRF150F with the idle issue (common topic it seems). I have read a lot of posts regarding this issue and most point to dirty, clogged pilot jet (my pilot jet and hole are clean). Here is a video link to my symptoms.
Bike is jetted 42/115 with main needle set at 4th groove from the top.
Pilot (air/fuel) screw 2 turns out
Freshly cleaned and oiled K&N filter
FMF exhaust.
What I did so far: Carburetor stripped and ultrasonic bath cleaned (pilot jet cleaned twice at this point), inspected carb to head manifold and seals, inspected intake rubber boot. Replaced pilot (air/fuel) screw rubber o-ring.
The symptoms are:
0 choke - bike will not idle, and sputters heavily with throttle applied.
1/2 choke - idles fine, and sputters slightly with higher throttle input.
full choke - idles and revs perfectly.
Any ideas what would cause this?
Thanks