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Kawasaki Vulcan 750 Troubleshooting Guide

Photo courtesy of Evan "The Bulldog" Breyn - VROC #485

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Scroll down, or pick an ailment from this list...

 Engine Doesn't Start, Starting Difficulty
 Poor Running at Low Speed
 Poor Running or No Power at High Speed

Poor Running in general

 Overheating
 Over Cooling
 Clutch Operation Faulty
 Gear Shifting Faulty
 Abnormal Engine Noise
 Abnormal Drive Train Noise
 Abnormal Frame Noise
 Oil Pressure Warning Light Goes On
 Exhaust Smokes Excessively
 Handling and/or Stability Unsatisfactory
 Brake Doesn't Hold
 Battery Problems




Engine Doesn't Start, Starting Difficulty:

Starter motor not rotating:

Starter lockout or neutral switch trouble
Starter motor trouble
Battery voltage low
Relays not contacting or operating
Starter button not contacting
Wiring open or shorted
Ignition switch trouble
Engine stop switch trouble
Fuse blown

Starter motor rotating but engine doesn't turn over:

Starter clutch trouble

Engine won't turn over:

Valve seizure
Cylinder, piston seizure
Connecting rod small end seizure
Connecting rod big end seizure
Transmission gear or bearing seizure
Camshaft seizure
Balancer bearing seizure

No fuel flow:

Fuel tap vacuum hose clogged
Fuel tank air vent obstructed
Fuel tap clogged
Fuel line clogged
Float valve clogged

Engine flooded:

Fuel level in carburetor float bowl too high
Float valve worn or stuck open
Starting technique faulty
(When flooded, crank the engine with the throttle fully open to allow more air to reach the engine)

No spark; spark weak:

Battery voltage low
Spark plug dirty, broken, or maladjusted
Spark plug cap or high tension wiring trouble
Spark plug cap not in good contact
Spark plug incorrect
IC ignitor trouble
Neutral, starter lockout, or side stand switch trouble
Pickup coil trouble
Ignition coil trouble
Ignition or engine stop switch shorted
Wiring shorted or open
Fuse blown

Compression low

Spark plug loose
Cylinder head not sufficiently tightened down
Cylinder, piston worn
Piston ring bad (worn, weak, broken, or sticking)
Piston ring/land clearance excessive
Cylinder head gasket damaged
Cylinder head warped
Valve spring broken or weak
Valve not seating properly (valve bent, worn, or carbon accumulation on the seating surface)
Hydraulic lash adjuster damaged (worn, seizure, or spring broken)
Hydraulic lash adjuster oil passage clogged

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Poor Running at Low Speed:

Spark weak:

Battery voltage low
Spark plug dirty, broken, or maladjusted
Spark plug cap or high tension wiring trouble
Spark plug cap shorted or not in good contact
Spark plug incorrect
IC ignitor trouble
Pickup coil trouble
Ignition coil trouble

Fuel/air mixture incorrect:

Pilot screw maladjusted
Pilot jet, or air passage clogged
Air bleed pipe, bleed holes clogged
Pilot passage clogged
Air cleaner clogged, poorly sealed, or missing
Starter plunger stuck open
Fuel level in carburetor float chamber too high or too low
Fuel tank air vent obstructed
Carburetor holder loose
Surge tank duct loose

Compression low:

Spark plug loose
Cylinder head not sufficiently tightened down
Cylinder, piston worn
Piston ring bad (worn, weak, broken, or sticking)
Piston ring/land clearance excessive
Cylinder head gasket damaged
Cylinder head warped
Engine not sufficiently warmed up after lash adjuster installation
Valve spring broken or weak
Valve not seating properly (valve bent, worn, or carbon accumulation on the seating surface)
Hydraulic lash adjuster damaged (worn, seizure, or spring broken)
Hydraulic lash adjuster oil passage clogged

Backfiring when decelerating:

Vacuum switch valve broken
Air suction valve trouble
Coasting enricher trouble

Other:

IC ignitor trouble
Carburetors not synchronizing
Carburetor vacuum piston doesn't slide smoothly
Engine oil viscosity too high
Drive train trouble
Final gear case oil viscosity too high
Brake dragging
Air suction valve trouble
Vacuum switch valve trouble
 
 

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Poor Running or No Power at High Speed:

Firing incorrect:

Spark plug dirty, broken, or maladjusted
Spark plug cap shorted or not in good contact
Spark plug incorrect
IC ignitor trouble
Pickup coil trouble
Ignition coil trouble

Fuel/air mixture incorrect:

Starter plunger stuck open
Main jet clogged or wrong size
Jet needle or needle jet worn
Air jet clogged
Fuel level in carburetor float chamber too high or too low
Bleed holes of air bleed pipe or needle jet clogged
Air cleaner clogged, poorly sealed, or missing
Surge tank duct poorly sealed
Water or foreign matter in fuel
Carburetor holder loose
Fuel tank air vent obstructed
Fuel tap clogged
Fuel line clogged

Compression low:

Spark plug loose
Cylinder head not sufficiently tightened down
Cylinder, piston worn
Piston ring bad (worn, weak, broken, or sticking)
Piston ring/land clearance excessive
Cylinder head gasket damaged
Cylinder head warped
Engine not sufficiently warmed up after lash adjuster installation
Valve spring broken or weak
Valve not seating properly (valve bent, worn, or carbon accumulation on the seating surface)
Hydraulic lash adjuster damaged (worn, seizure, or spring broken)
Hydraulic lash adjuster oil passage clogged

Knocking:

Carbon built up in combustion chamber
Fuel poor quality or incorrect
Spark plug incorrect
Coasting enricher trouble

Miscellaneous:

Throttle valve won't fully open
Carburetor vacuum piston doesn't slide smoothly
Brake Dragging
Clutch slipping
Overheating
Engine oil level too high
Engine oil viscosity too high
Drive train trouble
Final gear case oil viscosity too high
Air suction valve trouble
Vacuum switch valve trouble
Balancer mechanism malfunctioning
 
 

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Overheating:

Firing incorrect:

Spark plug dirty, broken, or maladjusted
Spark plug incorrect
IC ignitor trouble

Fuel/air mixture incorrect:

Main jet clogged or wrong size
Fuel level in carburetor float chamber too low
Carburetor holder loose
Air cleaner clogged, poorly sealed, or missing
Surge tank duct poorly sealed

Compression high:

Carbon built up in combustion chamber

Engine load faulty:

Clutch slipping
Engine oil level too high
Engine oil viscosity too high
Drive train trouble
Final gear case oil viscosity too high
Brake dragging

Lubrication inadequate:

Engine oil level too low
Engine oil poor quality or incorrect

Gauge incorrect:

Water temperature gauge broken
Water temperature sensor broken

Coolant incorrect:

Coolant level too low
Coolant deteriorated

Cooling system component incorrect:

Radiator clogged
Thermostat trouble
Radiator cap trouble
Thermostatic fan switch trouble
Fan relay trouble
Fan motor broken
Fan blade damage
Water pump not turning
Water pump impeller damaged
 
 

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Over Cooling:

Gauge incorrect:

Water temperature gauge broken
Water temperature sensor broken

Cooling system component incorrect:

Thermostatic fan switch trouble
Thermostat trouble
 
 

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Clutch Operation Faulty:

Clutch slipping:

No clutch lever play
Friction plate worn or warped
Steel plate worn or warped
Clutch spring broken or weak
Clutch release mechanism trouble
Clutch hub or housing unevenly worn
Clutch inner cable catching

Clutch not disengaging properly:

Clutch lever play excessive
Clutch plate warped or too rough
Clutch spring compression uneven
Engine oil deteriorated
Engine oil viscosity too high
Engine oil level too high
Clutch housing frozen on drive shaft
Clutch release mechanism trouble
Clutch hub locknut loose
 
 

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Gear Shifting Faulty:

Doesn't go into gear; shift pedal doesn't return

Clutch not disengaging
Shift fork bent or seized
Gear stuck on the shaft
Gear position lever binding
Shift return spring weak or broken
Shift return spring pin loose
Shift mechanism arm spring broken
Shift mechanism arm broken
Shift pawl broken

Jumps out of gear:

Shift fork worn
Gear groove worn
Gear dogs and/or dog holes worn
Shift drum groove worn
Gear positioning lever spring weak or broken
Shift fork pin worn
Drive shaft, output shaft, and/or gear splines worn

Overshifts:

Gear positioning lever spring weak or broken
Shift mechanism arm spring broken
 
 

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Abnormal Engine Noise:

Knocking:

IC ignitor trouble
Carbon built up in combustion chamber
Fuel poor quality or incorrect
Spark plug incorrect
Overheating

Piston slap:

Cylinder/piston clearance excessive
Cylinder, piston worn
Connecting rod bent
Piston pin, piston holes worn

Valve noise:

Engine not sufficiently warmed up after lash adjuster installation
Hydraulic lash adjuster damaged (worn, seizure, or spring broken)
Air in hydraulic lash adjuster
Metal chips or dust dammed in hydraulic lash adjuster
Engine operated in red zone
Valve spring broken or weak
Camshaft bearing worn

Other noise:

Connecting rod small end clearance excessive
Connecting rod big end clearance excessive
Piston ring worn, broken or stuck
Piston seizure, damage
Cylinder head gasket leaking
Exhaust pipe leaking at cylinder head connection
Crankshaft runout excessive
Engine mounts loose
Crankshaft bearing worn
Primary gear worn or chipped
Camshaft chain tensioner trouble
Upper or lower tension spring trouble
Camshaft chain, sprocket, guide worn
Air suction valve damaged
Balancer gear worn or chipped
Balancer shaft position maladjusted
Balancer bearing worn
Balancer coupling rubber damper damaged
Oil pump chain, sprocket worn
 
 

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Abnormal Drive Train Noise:

Clutch noise:

Weak or damaged rubber damper
Clutch housing/friction plate clearance excessive
clutch housing gear worn

Transmission noise:

Bearings worn
Transmission gears worn or chipped
Metal chips jammed in gear teeth
Engine oil insufficient

Drive line noise:

Bevel gear bearings worn
Bevel gears worn or chipped
Bevel gears maladjusted
Rear wheel coupling damaged
Insufficient lubricant
 
 

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Abnormal Frame Noise:

Front fork noise:

Oil insufficient or too thin
Spring weak or broken

Rear shock absorber noise:

Shock absorber damaged

Disc brake noise:

Pad installed incorrectly
Pad surface glazed
Disc warped
Caliper trouble

Drum brake noise:

Brake linings overworn or worn unevenly
Drum worn unevenly or scored
Brake springs weak or broken
Foreign matter in hub
Brake not properly adjusted

Other noise:

Bracket, nut, bolt, etc. not properly mounted or tightened
 
 

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Oil Pressure Warning Light Goes On:

Engine oil pump damaged
Engine oil screen clogged
Engine oil filter clogged
Engine oil level too low
Engine oil viscosity too low
Camshaft bearings worn
Crankshaft bearings worn
Oil pressure switch damaged
Wiring damaged
Relief valve stuck open
O-ring at the oil pipe in the crankcase damaged
 
 

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Exhaust Smokes Excessively:

White smoke:

Piston oil ring worn
Cylinder worn
Valve oil seal damaged
Valve guide worn
Engine oil level too high

Black smoke:

Air cleaner clogged
Main jet too large or fallen off
Starter plunger stuck open
Fuel level in carburetor float chamber too high

Brown smoke:

Main jet too small
Fuel level in carburetor float chamber too low
Surge tank duct loose
Air cleaner poorly sealed or missing
 
 

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Handling and/or Stability Unsatisfactory:

Handlebar hard to turn:

Steering stem locknut too tight
Bearing damaged
Steering bearing lubrication inadequate
Steering stem bent
Tire air pressure too low

Handlebar shakes or excessively vibrates:

Tire worn
Swing arm pivot bearing worn
Rim warped, or not balanced
Wheel bearing worn
Handlebar clamp loose
Steering stem head bolt loose

Handlebar pulls to one side:

Frame bent
Wheel misalignment
Swing arm bent or twisted
Steering maladjusted
Front fork bent
Right/left fork oil level uneven
Right/left rear shock absorbers unbalanced

Shock absorption unsatisfactory:

(Too hard)
Front fork oil excessive
Front fork oil viscosity too high
Front fork air pressure too high
Rear shock absorber air pressure too high
Tire air pressure too high
Front fork bent
(Too soft)
Front fork oil insufficient and/or leaking
Front fork oil viscosity too low
Front fork, rear shock absorber spring weak
Rear shock absorber oil leaking
 
 

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Brake Doesn't Hold:

Disc brake:

Air in the brake line
Pad or disk worn
Brake fluid leak
Disc warped
Contaminated pad
Brake fluid deteriorated
Primary or secondary cup damaged
Master cylinder scratched inside

Drum brake:

Brake maladjusted
Brake linings or drum worn
Overheated
Water in brake drum
Brake cam, camshaft worn
Oil on brake linings
 
 

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Battery Discharged:

Battery faulty (e.g., plates sulfated, shorted through sedimentation, electrolyte level too low)
Battery leads making poor contact
Load excessive (e.g., bulb of excessive wattage)
Ignition switch trouble
Regulator/Rectifier trouble
Stator coil open or short
Wiring faulty

Battery Overcharged:

Alternator trouble
Regulator/Rectifier trouble
Battery trouble
Wiring faulty
 
 

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.This page last updated Saturday, October 30, 2004 12:53 AM