1986-1989 Honda TRX250 FourTrax 250R Service Manual, Page 214Get this manual
TROUBLESHOOTING 9Check if engine overheats ENGINE IS NOT OVERHEATED ENGINE Ovm-EAlS Excessive carbon build-up in combustion chamber Use of improper quality fuel Mixture too lean Clutch slipping Clogged radiator Worn piston and cylinder Fuel-air mixture too lean Excessive carbon build-up in combustion chamber Ignition timing advanced too far (Faulty COl unit)
10Accelerate or run at high speed
ENGINE DOES NOT KNOCK
POOR PERFORMANCE AT LOW AND IDLE SPEEDS
CHECK 1Check ignition timing NORMAL 2Check carburetor air screw adjustment NORMAL 3Air is leaking past carburetor gasket NOT LEAKING Remove spark plug and try GOOD SPARK LEAKING-cINCORRECT-'eFuel-air mixture too lean (To correct, tu rn screw out) Fuel-air mixture too rich (To correct, tu rn screw in) Deteriorated insulator or reed valve gasket Loose carburetor CONDITION INCORRECT-cPROBABLE CAUSE Faulty COl unit Faulty pulse generator