Yamaha YZ250X 2022 Owner's Service Manual page 247

Symptom
—
Possible cause
Water or foreign material in fuel,
degraded fuel
Clogged carburetor air passage
Incorrectly adjusted throttle cable
Improperly synchronized carbure-
tors
Incorrectly adjusted pilot screw
Incorrectly adjusted pilot air screw Adjust the pilot air screw.
Clogged pilot jet
Loose pilot jet
Clogged main nozzle
Loose main nozzle
Clogged main jet
Loose main jet
Bent, damaged, or worn jet needle Replace the jet needle.
Cracks or damage in the piston
valve diaphragm
Problem with piston valve move-
ment (movement is not smooth)
Damaged or worn needle valve
seat
Loose needle valve seat
Damaged or worn needle valve
Incorrect fuel level
Bent, worn, or damaged starter
plunger
Incorrectly adjusted starter cable
Clogged or damaged carburetor
breather hose
Incorrect throttle position sensor
angle
9-4
TROUBLESHOOTING
Actions
Change fuel.
Clean the carburetor.
Adjust the throttle grip free play.
Adjust synchronization of carbure-
tors.
Adjust the pilot screw.
Clean the pilot jet.
Tighten the pilot jet to the specified
torque.
Clean the main nozzle.
Tighten the main nozzle to the
specified torque.
Clean the main jet.
Tighten the main jet to the speci-
fied torque.
Replace the piston valve dia-
phragm.
Replace the piston valve.
Replace the needle valve seat.
Tighten the needle valve seat to
the specified torque.
Replace the needle valve.
Adjust the fuel level to the proper
level.
Replace the starter plunger.
Adjust the starter cable.
Clean, repair, or replace the car-
buretor breather hose.
Adjust the throttle position sensor
angle.