Yamaha YZ250 2021 Owner's Manual

TROUBLESHOOTING7-4—Water or foreign material in fuel,degraded fuel Change fuel.Clogged carburetor air passage Clean the carburetor.Incorrectly adjusted throttle cable Adjust the throttle grip free play.Improperly synchronized carbure-torsAdjust synchronization of carbure-tors.Incorrectly adjusted pilot screw Adjust the pilot screw.Incorrectly adjusted pilot air screw Adjust the pilot air screw.Clogged pilot jet Clean the pilot jet.Loose pilot jet Tighten the pilot jet to the specifiedtorque.Clogged main nozzle Clean the main nozzle.Loose main nozzle Tighten the main nozzle to thespecified torque.Clogged main jet Clean the main jet.Loose main jet Tighten the main jet to the speci-fied torque.Bent, damaged, or worn jet needle Replace the jet needle.Cracks or damage in the pistonvalve diaphragmReplace the piston valve dia-phragm.Problem with piston valve move-ment (movement is not smooth) Replace the piston valve.Damaged or worn needle valveseat Replace the needle valve seat.Loose needle valve seat Tighten the needle valve seat tothe specified torque.Damaged or worn needle valve Replace the needle valve.Incorrect fuel level Adjust the fuel level to the properlevel.Bent, worn, or damaged starterplunger Replace the starter plunger.Incorrectly adjusted starter cable Adjust the starter cable.Clogged or damaged carburetorbreather hoseClean, repair, or replace the car-buretor breather hose.Incorrect throttle position sensorangleAdjust the throttle position sensorangle.Symptom Possible cause Actions