Segment:
Lightweight Dual-Sport / Supermoto
Target Audience:
Adventure riders, commuters, urban riders seeking a versatile and robust machine.
Competitors:
KTM 640/690 Enduro/Duke, Honda XR650L, Suzuki DR-Z400S/SM, Kawasaki KLR650.
Engine Type:
Liquid-cooled, 4-stroke, SOHC, 4-valve single-cylinder.
Fuel Delivery:
Electronic Fuel Injection (EFI) for most markets, ensuring precise fuel metering and emissions control.
Suspension Type:
Long-travel telescopic front forks and adjustable rear monoshock for off-road capability (XT660R) or stiffened for road performance (XT660X).
Engine:
Complete overhaul, diagnosis, tuning, lubrication, cooling, fuel system (injection/carburetion, depending on market variant), exhaust system.
Transmission:
Gearbox inspection, repair, clutch system, final drive (chain/sprockets).
Chassis:
Frame inspection, suspension (front forks, rear shock absorber), steering system, wheels, tires, brake systems (front/rear discs, calipers, master cylinders, hydraulic lines), electrical system (wiring diagrams, battery, charging system, ignition, lighting, instrumentation).
Maintenance:
Regular servicing, oil changes, filter replacements, chain adjustment, brake fluid changes, coolant checks, spark plug replacement, valve clearance checks.
Repair:
Engine rebuilds, gearbox overhauls, suspension component replacement, brake caliper rebuilding, electrical component diagnosis and replacement, bodywork repair.
Troubleshooting:
Diagnostic procedures for common and uncommon faults, fault code interpretation (if applicable), electrical troubleshooting charts.
Depth:
Comprehensive, suitable for DIY mechanics and professional workshops. Covers everything from routine maintenance to complete engine and transmission rebuilds. Includes detailed torque specifications and diagnostic procedures.
Bore X Stroke:
100.0 mm x 84.0 mm
Compression Ratio:
10.0:1
Engine Cooling:
Liquid-cooled
Valve Actuation:
SOHC, 4 valves per cylinder
Starting System:
Electric Start
Horsepower Est:
47.3 HP @ 6000 RPM
Torque Est:
60.8 Nm @ 5250 RPM
Fuel Injection:
Yamaha Electronic Fuel Injection (YEC-FI), dual throttle valves
Fuel Tank Capacity:
15 Liters (approx. 3.96 US gallons)
Recommended Fuel:
Unleaded gasoline, 95 octane (RON)
Ignition:
TCI (Transistor Controlled Ignition)
Type:
5-speed constant mesh
Clutch:
Wet, multiple-disc, cable operated
Final Drive:
O-ring sealed chain
Gear Ratios:
Detailed gear ratios are provided within the manual for accurate performance analysis and diagnostics.
Transmission Fluid Spec:
Refer to manual for specific type and capacity; typically a high-quality motorcycle gear oil is recommended.
Crash Safety:
Motorcycles are not typically rated by organizations like NHTSA or Euro NCAP. Safety primarily relies on rider skill and adherence to maintenance.
Braking System:
Hydraulic dual disc front brake, hydraulic rear disc brake. ABS was not a standard or common option for these model years.
Lighting:
Halogen headlight, LED taillight, incandescent turn signals. The manual details electrical system diagnostics for lighting.
Frame Construction:
Steel diamond frame providing robust support.
Dashboard:
Digital LCD instrument cluster displaying speedometer, tachometer, odometer, trip meters, fuel gauge, clock, and warning lights. Detailed diagnostic information is accessible via the manual.
ABS Availability:
Not typically equipped with ABS during this production run. Manual focuses on mechanical and hydraulic brake system maintenance.
Diagnostic Ports:
OBD-II diagnostic connector for EFI system analysis, covered extensively in the manual.
Oil Change Interval:
Every 5,000 km or 6 months, whichever comes first (refer to manual for precise interval based on usage).
Air Filter Cleaning:
Every 5,000 km, or more frequently in dusty conditions.
Spark Plug Replacement:
Every 10,000 km.
Valve Clearance Check:
Every 10,000 km.
Brake Fluid Change:
Every 2 years or as recommended by condition.
Engine Oil Type:
Yamalube 4 (10W-40) or equivalent API SG or higher, JASO MA certified (refer to manual for exact specification).
Coolant Type:
High-quality ethylene glycol-based antifreeze mixed with distilled water (50:50 ratio). Refer to manual for specific Yamaha coolant or equivalent.
Brake Fluid Type:
DOT 4 hydraulic brake fluid.
Common Wear Items:
Clutch plates, brake pads, fork seals, wheel bearings, exhaust gasket, fuel pump diaphragm (in some cases).
Performance Quirks:
Some owners report a slight hesitation or stuttering at specific RPMs, often resolvable with ECU remapping or fuel system adjustments detailed in advanced sections of the manual.
Electrical Notes:
Check battery terminals for corrosion; ensure proper grounding. Wiring harness integrity is crucial for reliable EFI operation.
Yamaha Motorcycles:
Yamaha Motor Company is a Japanese manufacturer with a long and distinguished history in motorcycle production, known for innovation and performance across various segments, including off-road and sport motorcycles.
Xt Series:
The XT designation has a storied history in Yamaha's dual-sport lineup, tracing back to the original XT500. The XT660 lineage continued this tradition, offering a more modern and powerful single-cylinder package for riders seeking versatility.
Manufacturing Location:
Primarily manufactured in Japan by Yamaha Motor Company.
Production Years:
2004-2008 for this specific manual coverage. The XT660 platform continued in various forms and markets beyond 2008.
