1985-1986 Honda ATC250R Shop Manual, Page 234Get this manual
TROUBLESHOOTING
t Check oil levelAlso check
oil for contamination TRANSMISSION IS FILLED TO PROPER LEVEL
SYMPTOM
PROBABLE CAUSE
OIL LEVEL INCORRECT-1(1) Oil level too high (2) Oil level too low (3) Contaminated oil
10Check if engine overheats
ENGINE IS NOT OVERHEATED
11Accelerate or run at high speed
ENGINE DOES NOT KNOCK
ENGINE OVERHEATSi(1) Excessive carbon build-up in combustion chamber (2) Use of improper quality fuel (3) Mixture too lean (4) Clutch slipping ENGINE KNOCKSt(1) Worn piston and cylinder (2) Fuel-air mixture too lean (3) Excessive carbon build-up in combustion chamber (4) Ignition timing too advanced (Faulty COl unit)
POOR PERFORMANCE AT LOW AND IDLE SPEEDS