Honda CRF450L 2019 Owner's Manual & Off-Road Handbook page 172

If Your Engine Quits or Won't Start
SYMPTOM: Engine starts, but runs poorly.
POSSIBLE CAUSE WHAT TO DO
idles roughly, too fast, stalls Check engine idle adjustment (page 80). If the problem persists, see
your dealer.
overheating Check the coolant temperature indicator. Refer to If the High Coolant
Temperature Indicator Lights, page 170.
runs erratically, misfires May damage catalytic converter. See your dealer.
blubbers (rich fuel mixture) See your dealer.
sooty exhaust (rich fuel See your dealer.
mixture)
detonates or pings under If applicable, switch to the recommended octane gasoline (page 60) or
load change your brand of gasoline. If the problem persists, see your
dealer.
afterfires (backfires) May damage catalytic converter. See your dealer.
pre-ignition (runs on after May damage catalytic converter. See your dealer.
ignition switched OFF)
166
Taking Care of the Unexpected