1981-1984 Official Honda ATC250R Shop Manual, Page 183Get this manual
ATe 250R CHECK 9Call levelAlso check heck oil for contamination TRANSMISSION IS FILLED TO PROPER LEVEL SYMPTOM OIL LEVEL INCORRECT
TROUBLESHOOTING
PROBAB LE CAUSE
(1Oil level too high (2) Oil level too low (3) Contaminated oil
10Check if engi ne overheats ENGINE IS NOT OVERHEATED
ENG INE OVERHEATS
( 1) Excessive carbon build-up in combustion chamber (2) Use of improper quality fuel (3) Mixture too lean (4) Clutch slipping (1Worn 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)
11 Accelerate or run at high speed ENGINE DOES NOT KNOCK
ENGINE KNOCKS
POOR PERFORMANCE AT LOW AND IDLE SPEEDS