Market Segment:
High-performance sport ATV, positioned for racing and aggressive recreational riding.
Competitors:
Honda TRX450R, Suzuki LT-R450, Kawasaki KFX450R.
Vehicle Highlights:
Known for its potent 5-valve titanium cylinder head engine, lightweight design, and aggressive styling, the YFZ450S was a dominant force in its class.
Manual Benefit:
Provides essential information for maintaining peak performance, diagnosing issues, and executing repairs on the 2004 Yamaha YFZ450S.
Engine Management:
Combustion specs, fuel system, lubrication, cooling, intake, exhaust, spark plug, CDI, ignition coil.
Powertrain:
Transmission, gearbox, drive train, clutch (including charging clutch), con rod, crankshaft, camshaft, cylinder, piston, rings, cams, primary reduction gear, shaft.
Chassis And Body:
Wheel and steering system, frame, sub-frame, body and fender assembly, handlebars, seat, fuel tank, oil tank, skid plate, decals, plastic body panels.
Electrical:
Electrical system, starter, stator, magneto, flywheel, battery, rectifier, charge system, switches (start, kill, switch, button), wiring diagram.
Brakes And Suspension:
Brakes, brake pads, rotor, hydraulic system, suspension (front and rear), struts, swingarm, axle, boots.
Diagnostic And Troubleshooting:
Advanced level troubleshooting, error code analysis, problem identification and resolution for various systems.
Maintenance:
Routine maintenance, lubrication schedules, fluid changes (oil, coolant), filter replacement, air filter cleaning.
Repair And Overhaul:
Engine installation/removal, complete engine overhaul, transmission rebuild, carburetor adjustment/rebuild (including jetting), clutch service, brake system repair, steering system overhaul.
Component Replacement:
Replacement of pistons, rings, gaskets, bearings (wheel, gearbox), sprockets, chains, lamps, bulbs, throttle cables, water pump, starter motor, kickstart mechanism, thermostat.
Depth:
Detailed step-by-step instructions, torque specifications, critical notes, cautions, and warnings for all repair procedures, suitable for professional mechanics and advanced DIY enthusiasts.
Engine Type:
4-stroke, liquid-cooled, DOHC, 5-valve, Titanium cylinder head
Bore X Stroke:
95.0 mm x 63.1 mm
Compression Ratio:
11.4:1
Horsepower Estimate:
Approx. 45-50 HP (at crankshaft, manufacturer's estimate)
Torque Estimate:
Approx. 30-32 lb-ft (manufacturer's estimate)
Carburetion:
Keihin 37mm flat-slide carburetor with TPS (Throttle Position Sensor)
Fuel Type:
Unleaded gasoline, minimum 87 octane
Oil Type:
Yamalube 4 (or equivalent) 10W-40 API SG or higher
Oil Capacity:
1.90 L (2.01 US qt) with oil filter change
Coolant Type:
Permanent type anti-freeze coolant (50/50 mix with distilled water)
Coolant Capacity:
1.3 L (1.37 US qt)
Ignition System:
CDI (Capacitor Discharge Ignition)
Starter:
Electric starter and a mechanical decompression system/kickstart lever.
Transmission Type:
Constant mesh 5-speed sequential
Clutch Type:
Wet, multiple-disc, cable operated, assisted clutch
Gear Ratios:
1st: 2.438 (29/10), 2nd: 1.765 (30/17), 3rd: 1.333 (28/21), 4th: 1.111 (20/18), 5th: 0.917 (22/20)
Final Drive:
O-ring sealed chain
Gear Oil Type:
Yamalube 4 (or equivalent) 10W-40 API SG or higher
Gear Oil Capacity:
0.55 L (0.58 US qt)
Safety Features Overview:
Designed for experienced riders, emphasizes rider skill and responsible operation; lacks electronic driver aids common in modern vehicles.
Braking System:
Hydraulic disc brakes front and rear with braided stainless steel lines for enhanced feel and performance.
Chassis Design:
Strong, lightweight aluminum frame and sub-frame for stability and handling.
Control Features:
Wide handlebars for leverage, ergonomic seating position.
Engine Oil Change:
Every 10 hours of operation or monthly, whichever comes first (severe use); Every 20 hours or 3 months (normal use).
Air Filter Cleaning:
Clean every 5-10 hours or more frequently in dusty conditions.
Spark Plug Inspection:
Inspect every 10 hours of operation.
Chain Lubrication Adjustment:
Lubricate every 10 hours, adjust tension every 20 hours.
Engine Oil Specification:
Yamalube 4 (or equivalent) 10W-40, API SG or higher.
Coolant Specification:
Permanent type anti-freeze (50/50 mix with distilled water).
Common Concerns:
Potential for carburetor jetting to require adjustment for optimal performance at different altitudes/conditions; some early models may have had clutch or transmission wear concerns under extreme racing use; overheating if cooling system is not properly maintained.
Typical Parts:
Carburettor kits, oil filters (e.g., Yamaha 3XF-13440-00-00), pistons, gaskets, brake pads, sprockets, chains, wheel bearings, tires, oil.
