February 26, 2024

 

GENERAL INFORMATION

Troubleshooting information provided here does not cover all the trouble symptoms, possible causes, and remedial actions. Some items may not apply depending on the model. Use this information as a guide and quick reference matrix when performing basic troubleshooting. Refer to the each chapter for detailed information on checking, adjustment, and replacement.

TROUBLESHOOTING OF ENGINE (fault code not detected)

If a fault code is detected, refer to the FUEL INJECTION SYSTEM.

Engine does not crank.

Symptom

Possible cause

Actions

Starter motor does not operate

Refer to TROUBLESHOOTING under ELECTRIC STARTING SYSTEM.

Starter motor operates, but the engine does not crank.

Starter clutch malfunction

Replace the starter clutch.

Improper oil grade (starter clutch slipping)

Change to recommended engine oil.

Stuck piston or seized crankshaft

Disassemble and check the engine. Replace defective parts.

Engine will not start or is difficult to start, but it cranks.

Symptom

Possible cause

Actions

Spark plug does not produce a spark

Refer to TROUBLESHOOTING under IGNITION SYSTEM.

Fuel not supplied

Measure the fuel pressure.

Empty fuel tank

Fill the fuel tank with fuel.

Clogged fuel tank cap breather hole

Clean the fuel tank cap.

Clogged or damaged fuel hose

Clean, repair, or replace the fuel hose.

Fuel leakage

Check the fuel passage. Repair or replace as necessary.

Clogged fuel pump

Clean or replace the fuel pump.

Cracks or damage in fuel pump

Replace the fuel pump.

Fuel pump malfunction

Refer to TROUBLESHOOTING under FUEL PUMP SYSTEM.

Failed or clogged fuel injector

Replace the fuel injector.

ECU failure

Replace the ECU.

Water or foreign material in fuel, degraded fuel

Change fuel.

Loose spark plug

Tighten the spark plug to the specified torque.

Loose cylinder head or cylinder

Tighten bolts or nuts on cylinder head and cylinder to the specified torque.

Damaged cylinder head gasket

Replace the cylinder head gasket.

Incorrect valve timing

Adjust the valve timing.

Incorrect valve clearance

Adjust the valve clearance.

Worn valve guide

Replace the valve guide.

Bent, damaged, or stuck valve

Replace the valve.

Poor contact between valve and valve seat

Reface the valve-to-valve-seat contact.

Fatigued or broken valve spring

Replace the valve spring.

Worn, damaged, or stuck piston ring

Replace the piston and piston rings as a set.

Seized or damaged piston

Replace the piston and piston rings as a set.

Worn or damaged cylinder bore

Replace the cylinder, piston, and piston rings as a set.

Incorrect idling speed or mid-to-high speed

Symptom

Possible cause

Actions

Spark plug does not produce a spark

Incorrect spark plug gap

Adjust the spark plug gap.

Worn or damaged spark plug

Replace the spark plug.

Defective spark plug cap

Replace the spark plug cap.

Defective ignition coil

Replace the ignition coil.

ECU failure

Replace the ECU.

Low fuel pressure

Measure the fuel pressure.

Fuel leakage

Check the fuel passage. Repair or replace as necessary.

Clogged fuel pump

Clean or replace the fuel pump.

Cracks or damage in fuel pump

Replace the fuel pump.

Fuel pump malfunction

Refer to TROUBLESHOOTING under FUEL PUMP SYSTEM.

Fuel not supplied

Failed or clogged fuel injector

Replace the fuel injector.

ECU failure

Replace the ECU.

Worn camshaft lobe

Replace the camshaft.

Water or foreign material in fuel, degraded fuel

Change fuel.

Contaminated throttle body or clogged internal passage

Clean the throttle body.

Incorrectly adjusted throttle cable

Adjust the throttle grip free play.

Incorrectly adjusted idling speed (idle screw)

Adjust the idle screw.

Incorrect throttle position sensor angle

Adjust the throttle position sensor angle.

Incorrect acceleration position sensor angle

Adjust the acceleration position sensor angle.

Faulty ECU

Replace the ECU.

Clogged vacuum hose

Clean the vacuum hose.

Cracks and damage in vacuum hose

Replace the vacuum hose.

Damaged throttle body joint

Replace the throttle body joint.

Loose throttle body joint

Tighten the throttle body joint bolts to the specified torque.

Clogged air filter element

Clean or replace the air filter element.

Incorrect oil level (high)

Adjust the oil level to the specified level.

Excessive noise from engine

Symptom

Possible cause

Actions

Noise heard from around cylinder head

Incorrect valve clearance (too wide)

Adjust the valve clearance.

Fatigued or broken valve spring

Replace the valve spring.

Worn or damaged camshaft lobe

Replace the camshaft.

Worn or damaged valve lifter

Replace the valve lifter and cylinder head as a set.

Worn or damaged camshaft journal

Replace the camshaft.

Worn or damaged cylinder head (camshaft journal)

Replace the cylinder head.

Noise heard from around timing chain

Worn or damaged timing chain

Replace the timing chain and camshaft sprocket as a set.

Worn or damaged camshaft sprocket

Replace the timing chain and camshaft sprocket as a set.

Worn or damaged timing chain guide

Replace the timing chain guide.

Cracked, damaged, or faulty timing chain tensioner

Replace the timing chain tensioner.

Noise heard from around piston

Worn or damaged piston ring

Replace the piston and piston rings as a set.

Worn or damaged piston

Replace the piston and piston rings as a set.

Worn piston (piston pin hole)

Replace the piston and piston pin as a set.

Worn or damaged piston pin

Replace the piston pin.

Worn or damaged cylinder bore

Replace the cylinder, piston, and piston rings as a set.

Carbon buildup in piston head and combustion chamber

Clean the piston head and combustion chamber.

Noise heard from around crankshaft

Worn or damaged crankshaft journal or crank pin

Replace the crankshaft.

Cracked, worn, or damaged balancer shaft

Replace the balancer drive gear and balancer shaft as a set.

Worn or damaged balancer drive gear

Replace the balancer drive gear and balancer shaft as a set.

Worn or damaged big end bearing

Replace the big end bearing.

Worn or damaged crankshaft journal bearing

Replace the crankshaft journal bearing.

Worn or damaged balancer shaft journal bearing

Replace the balancer shaft journal bearing.

TROUBLESHOOTING OF CLUTCH

Manual clutch

Symptom

Possible cause

Actions

Clutch slippage

Improperly assembled clutch

Reassemble the clutch.

Improperly adjusted clutch cable

Adjust the clutch lever free play.

Loose clutch spring

Tighten the clutch spring bolts to the specified torque.

Fatigued clutch spring

Replace the clutch springs as a set.

Warped pressure plate

Replace the pressure plate.

Worn friction plate

Replace the friction plates as a set.

Warped or worn clutch plate

Replace the clutch plates as a set.

Incorrect oil level

Adjust the engine oil level to the specified level.

Incorrect oil viscosity (low)

Change to recommended engine oil.

Deteriorated oil

Change to recommended engine oil.

Clutch drags

Faulty clutch spring

Replace the clutch springs as a set.

Warped pressure plate

Replace the pressure plate.

Swollen friction plate

Replace the friction plates as a set.

Warped clutch plate

Replace the clutch plates as a set.

Bent pull rod (outer pull type)

Replace the pull rod.

Worn pull rod tooth (outer pull type)

Replace the pull rod and pull lever shaft as a set.

Bent push rod (inner push type)

Replace the push rod.

Damaged or worn clutch boss

Replace the clutch boss.

Seized clutch housing bushing

Replace the clutch housing.

Improperly installed pull lever

Align the match mark on the pull lever before installation.

Incorrect oil level

Adjust the engine oil level to the specified level.

Incorrect oil viscosity (high)

Change to recommended engine oil.

Deteriorated oil

Change to recommended engine oil.

Clutch noise

Damaged or worn primary driven gear

Replace the primary drive gear or crankshaft, and the clutch housing as a set.

Loose clutch boss nut

Tighten the clutch boss nut to the specified torque.

Fatigued clutch damper

Replace the clutch housing.

Worn clutch housing bearing

Replace the clutch housing bearing.

Worn pressure plate bearing

Replace the pressure plate bearing.

TROUBLESHOOTING OF TRANSMISSION

Symptom

Possible cause

Actions

Difficult or impossible to shift transmission gear

Clutch drags

Refer to “Clutch drags”.

Improperly adjusted shift rod

Adjust the shift rod installation length.

Bent shift shaft

Replace the shift shaft.

Foreign object in a shift drum groove

Remove foreign object from shift drum groove.

Damaged shift drum

Replace the shift drum.

Seized shift fork

Replace the shift fork and shift fork guide bar as a set.

Bent shift fork guide bar

Replace the shift fork guide bar.

Foreign object between transmission gears

Remove foreign object from transmission gears.

Seized transmission gear

Replace the seized gear and the axle as a set.

Improperly assembled transmission

Reassemble the transmission axle assembly.

Jumps out of gear

Incorrect shift pedal position

Adjust the shift pedal position.

Improperly returned stopper lever

Replace the stopper lever spring.

Bent or worn shift fork

Replace the shift fork.

Shift drum incorrect axial play

Replace the shift drum.

Worn shift drum groove

Replace the shift drum.

Worn transmission gear dog

Replace the transmission gear.

Transmission noise

Damaged or worn transmission gear

Replace the transmission gear.

Worn main axle spline

Replace the main axle.

Worn drive axle spline

Replace the drive axle.

Worn bearing

Replace the bearing.

TROUBLESHOOTING OF COOLING SYSTEM

Symptom

Possible cause

Actions

Overheating

Carbon buildup in piston head and combustion chamber

Clean the piston head and combustion chamber.

Clogged engine cooling water passages

Check and clean the engine cooling water passages.

Incorrect oil level

Adjust the oil level to the specified level.

Incorrect oil viscosity

Change to recommended engine oil.

Inferior oil quality

Change to recommended engine oil.

Low coolant level

Add recommended coolant to the specified level.

Damaged or leaking radiator

Replace the radiator.

Faulty radiator cap

Replace the radiator cap.

Clogged radiator fin

Clean the radiator fin.

Bent or damaged radiator fin

Repair the radiator fin or replace the radiator.

Damaged or faulty water pump

Replace the water pump.

Damaged hoses or pipes

Replace the hose or pipe.

Improperly connected hoses or pipes

Connect the hoses and pipes properly.

Damaged throttle body joint

Replace the throttle body joint.

Loose throttle body joint

Tighten the throttle body joint bolts to the specified torque.

Clogged air filter element

Clean or replace the air filter element.

Brake drags

Check the brake system and repair or replace faulty parts as necessary.

Incorrect spark plug gap

Adjust to the specified spark plug gap.

Incorrect spark plug heat range

Replace the spark plug with the one of the specified type.

Faulty ECU

Replace the ECU.

Noise from water pump

Contact between the water pump housing cover and impeller

Disassemble the water pump and replace faulty parts.

Worn water pump housing bearing

Replace the water pump housing bearing.

TROUBLESHOOTING OF BRAKE

Symptom

Possible cause

Actions

Poor performance of disc brake

Worn brake pad

Replace the brake pads as a set.

Worn or deflected brake disc

Replace the brake disc.

Air in hydraulic brake system

Bleed the hydraulic brake system.

Brake fluid leakage

Check the hydraulic brake system and repair or replace faulty parts as necessary.

Incorrect brake fluid level (low)

Add brake fluid to the specified level.

Stuck brake caliper piston

Replace the caliper piston seal.

Stuck brake caliper and slide pin

Lubricate the caliper slide pin.

Loose union bolt

Tighten the union bolt to the specified torque.

Damaged brake hose and brake pipe

Replace the brake hose and brake pipe.

Oil or grease on the brake disc or brake pad

Clean the brake disc or brake pad.

Insufficient lubrication of brake lever or brake pedal pivot

Lubricate the brake lever or brake pedal pivot.

TROUBLESHOOTING OF SUSPENSION

Symptom

Possible cause

Actions

Front fork is hard

Bent or damaged inner tube

Replace the inner tube.

Bent or damaged outer tube

Replace the outer tube.

Damaged or worn slide metal

Replace the slide metal.

Bent or damaged damper rod

Replace the damper rod.

Bent wheel axle

Replace the wheel axle.

Incorrect oil viscosity (high)

Change to recommended fork oil.

Incorrect oil level (high)

Adjust to the specified oil level.

Improperly adjusted spring preload (hard)

Adjust the spring preload.

Improperly adjusted rebound damping (hard)

Adjust the rebound damping.

Improperly adjusted compression damping (hard)

Adjust the compression damping.

Front fork is soft

Fatigued or broken fork spring

Replace the fork spring.

Incorrect oil viscosity (low)

Change to recommended fork oil.

Incorrect oil level (low)

Adjust to the specified oil level.

Improperly adjusted spring preload (soft)

Adjust the spring preload.

Improperly adjusted rebound damping (soft)

Adjust the rebound damping.

Improperly adjusted compression damping (soft)

Adjust the compression damping.

Leaking oil from front fork

Bent, damaged, or corroded inner tube

Replace the inner tube.

Cracked or damaged outer tube

Replace the outer tube.

Improperly installed oil seal

Replace the oil seal.

Damaged oil seal lip

Replace the oil seal.

Incorrect oil level (high)

Adjust to the specified oil level.

Loose damper rod assembly bolt

Tighten the damper rod assembly bolt to the specified torque.

Damaged damper rod assembly bolt copper washer

Replace the damper rod assembly bolt copper washer.

Cracked or damaged cap bolt O-ring

Replace the cap bolt O-ring.

Rear suspension is hard

Bent or damaged rear shock absorber rod

Replace the rear shock absorber.

Bent swingarm pivot shaft

Replace the swingarm pivot shaft.

Damaged or worn swingarm bearing or bushing

Replace the swingarm bearing or bushing.

Damaged or worn relay arm bearing

Replace the relay arm bearing.

Damaged or worn connecting arm bearing

Replace the connecting arm bearing.

Improperly adjusted rear shock absorber spring preload (hard)

Adjust the spring preload.

Improperly adjusted rear shock absorber rebound damping (hard)

Adjust the rebound damping.

Improperly adjusted rear shock absorber compression damping (hard)

Adjust the compression damping.

Rear suspension is soft

Oil leaking from rear shock absorber

Replace the rear shock absorber.

Gas leaking from rear shock absorber

Replace the rear shock absorber.

Fatigued or damaged rear shock absorber spring

Replace the rear shock absorber.

Improperly adjusted rear shock absorber spring preload (soft)

Adjust the spring preload.

Improperly adjusted rear shock absorber rebound damping (soft)

Adjust the rebound damping.

Improperly adjusted rear shock absorber compression damping (soft)

Adjust the compression damping.

Oil leaking from rear shock absorber

Bent, damaged, or corroded rear shock absorber rod

Replace the rear shock absorber.

Damaged oil seal lip

Replace the rear shock absorber.

TROUBLESHOOTING OF STEERING/HANDLING

Symptom

Possible cause

Actions

Handlebar wobble

Loose lower ring nut

Tighten the lower ring nut to the specified torque.

Worn bearing or bearing race

Replace the bearing and bearing race as a set.

Warped front fork

Repair or replace the front fork.

Bent front wheel axle

Replace the front wheel axle.

Incorrect tire pressure

Adjust to the specified tire pressure.

Worn, deformed, or incorrect tire

Replace the tire.

Heavy steering

Lower ring nut is tightened too tight.

Tighten the lower ring nut to the specified torque.

Bent lower bracket

Replace the lower bracket.

Broken bearing or bearing race

Replace the bearing and bearing race as a set.

Incorrect tire pressure

Adjust to the specified tire pressure.

Front wheel vibration

Loose spoke

Tighten the spoke and adjust the runout.

Damaged or worn wheel bearing

Replace the wheel bearing.

Worn, deformed, or incorrect tire

Replace the tire.

Loose wheel axle or wheel axle nut

Tighten the wheel axle or wheel axle nut to the specified torque.

Loose wheel axle pinch bolt

Tighten the wheel axle pinch bolt to the specified torque.

Incorrect front fork oil level

Adjust to the specified front fork oil level.

Rear wheel vibration

Loose spoke

Tighten the spoke and adjust the runout.

Damaged or worn wheel bearing

Replace the wheel bearing.

Worn, deformed, or incorrect tire

Replace the tire.

Loose wheel axle nut

Tighten the wheel axle nut to the specified torque.

Loose swingarm pivot shaft

Tighten the swingarm pivot shaft to the specified torque.

Bent or damaged swingarm

Replace the swingarm bearing.

Damaged or worn swingarm bearing or bushing

Replace the swingarm bearing or bushing.

TROUBLESHOOTING OF CHARGING SYSTEM

Symptom

Possible cause

Actions

Battery is not charged

Refer to TROUBLESHOOTING under CHARGING SYSTEM.

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