Troubleshooting - Honda CRF450R 2017 Owner's Manual & Competition Handbook

Table of Contents

Troubleshooting

The items that are serviceable using this Manual

are followed by the page number reference in

parenthesis. The items that require use of an

official Honda Service Manual are followed by an

asterisk (*).

ENGINE DOES NOT START OR IS HARD TO START

CHECK

POSSIBLE CAUSES

INCORRECT

1. Check the spark

• Incorrect spark plug heat

plug condition

range

(P.64)

• Incorrect spark plug gap

• Dirty air cleaner element

CORRECT

WEAK OR

2. Try spark test*

• Faulty spark plug (P.64)

NO SPARK

• Fouled spark plug (P.64)

GOOD SPARK

• Faulty ECM*

• Broken or shorted spark

plug wire

• Faulty alternator*

• Faulty ignition coil*

• Faulty engine stop

button*

• Loose or disconnected

ignition system wires

• Faulty CKP sensor*

• Faulty regulator/rectifier*

• Faulty condenser*

3. Check the PGM-FI

INCORRECT

• Faulty PGM-FI system

system (P.7)

(P.9)

CORRECT

4. Check the fuel

INCORRECT

• Faulty fuel pump*

pump operation

• Clogged fuel pump filter

and inspect the fuel

(P.44)

flow*

CORRECT

5. Check the fuel

INCORRECT

• Faulty PGM-FI system

injector operating

(P.9)

sound

• Faulty fuel injector

CORRECT

6. Test cylinder

LOW

• Valve clearance too small

compression*

• Valve stuck open

• Worn cylinder and piston

CORRECT

ring*

• Damaged cylinder head

gasket

• Improper valve timing*

• Seized valve

7. Start by following

ENGINE

• Insulator leaking

normal starting

STARTS BUT

• Improper ignition timing

procedure

SOON STOPS

(Faulty ECM or CKP

sensor)*

• Fast idle knob stuck open

or damaged

• Fuel contaminated

ENGINE LACKS POWER

CHECK

POSSIBLE CAUSES

1. Check the wheel

INCORRECT

• Brake dragging

spin smoothness

• Worn or damaged wheel

bearings

CORRECT

• Bent axle shaft

• Drive chain too tight

2. Check the tire

INCORRECT

• Faulty valve core

pressure (P.107)

• Punctured tire

CORRECT

3. Check the engine

NO GOOD

• Clutch slipping

speed change

• Improperly adjusted

accordingly when

clutch lever freeplay

clutch is engaged*

(P.59)

• Worn clutch discs/plates

GOOD

(P.62)

• Warped clutch discs/

plates (P.62)

• Weak clutch springs*

• Sticking clutch lifter

• Additive in engine oil

4. Check the engine

NO GOOD

• Dirty air cleaner element

speed increase

• Clogged muffler

• Fast idle knob stuck open

GOOD

or damaged

• Restricted fuel fill cap

breather tube

• Restricted fuel flow

5. Check the engine

YES

• Worn piston and cylinder*

knocking when

• Use of poor quality fuel

accelerate or run

• Excessive carbon build-

the engine at high

up in combustion

speed

chamber

• Ignition timing too

advance (Faulty ECM)*

• Lean fuel mixture

6. Check the ignition

INCORRECT

• Faulty ECM*

timing*

• Faulty CKP sensor*

CORRECT