Segment:
Beginner/Youth Off-Road Motorcycle
Target Audience:
Young riders, beginner motocross enthusiasts, recreational trail riders.
Key Competitors:
Honda CRF50/70, Suzuki JR50/80, Kawasaki KLX100/110.
Vehicle Design Philosophy:
Compact, user-friendly, durable, and easy to maintain for young riders.
Benefit To Owner:
Empowers owners to perform essential maintenance, diagnose issues, and conduct repairs, saving time and money while maximizing the motorcycle's lifespan and performance.
Engine:
Engine teardown, assembly, inspection, troubleshooting, specifications (carburetor, ignition, cooling, lubrication).
Transmission:
Gearbox inspection, disassembly, assembly, clutch operation, troubleshooting.
Chassis And Frame:
Frame inspection, suspension (front forks, rear shock), steering system, wheel bearings, swingarm.
Electrical System:
Wiring diagrams, lighting system, ignition system components, battery, charging system, starter system.
Braking System:
Front and rear brake system service, adjustment, troubleshooting, fluid specifications.
Fuel System:
Fuel tank, fuel lines, carburetor service, tuning, specifications.
Exhaust System:
Exhaust pipe and muffler service, inspection.
Bodywork And Plastics:
Body panel removal, installation, fender, seat, handlebar components.
Maintenance:
Routine service checks, oil changes, filter replacements, chain adjustment, lubrication points.
Troubleshooting:
Systematic diagnostic procedures for common and uncommon issues, fault finding charts.
Repair:
Step-by-step repair instructions for all major components and systems.
Disassembly And Assembly:
Detailed instructions for complete teardown and reassembly of the motorcycle.
Specifications And Measurements:
Torque values, clearances, tolerances for all serviceable parts.
Depth:
Comprehensive, covering from basic owner maintenance to full engine rebuilds and electrical diagnostics.
Engine Type:
Four-stroke, SOHC, Air-cooled
Bore X Stroke:
47 mm x 51.1 mm
Carburetor Model:
Mikuni VM17 (typical)
Ignition System:
CDI (Capacitor Discharge Ignition)
Starting System:
Kick starter
Horsepower:
Approx. 7-8 HP (est. at crankshaft)
Torque:
Approx. 6-7 Nm (est. at crankshaft)
Fuel Type:
Unleaded Gasoline
Fuel Tank Capacity:
3.5 Liters (0.9 US gal)
Oil Type:
Yamalube 4 (or API SE, SF, SG or SH Standard, SAE 10W-30) or similar motorcycle specific 4-stroke oil.
Oil Capacity:
0.9 Liters (0.95 US qt)
Transmission Type:
Constant mesh, 4-speed
Clutch Type:
Wet, multi-plate
Gear Ratios:
Detailed ratios available in manual (e.g., 1st: 2.833, 2nd: 1.706, 3rd: 1.235, 4th: 0.913)
Shifting Mechanism:
Clutch lever and foot shifter
Transmission Oil Type:
Yamalube 4 (or API SE, SF, SG or SH Standard, SAE 10W-30) or similar motorcycle specific 4-stroke oil.
Crash Test Results:
N/A (Off-road motorcycle, not subject to DOT/NHTSA crash testing)
Braking Type:
Drum brakes front and rear
Throttle Limiter:
Often features a throttle limiter screw for parental control (serviceable via manual).
Handlebars:
Knuckle guards often included or optional for hand protection.
Exhaust Heat Shield:
Present to prevent burns.
Engine Oil Change:
Every 1000 km (600 miles) or 6 months, whichever comes first. More frequent changes recommended for hard use.
Air Filter Cleaning:
Every 500 km (300 miles) or as needed in dusty conditions.
Spark Plug Inspection:
Every 1000 km (600 miles).
Chain Lubrication Adjustment:
Every 500 km (300 miles) or more frequently in wet/dirty conditions.
Valve Clearance Check:
Every 4000 km (2400 miles) or 24 months.
Engine Oil Grade:
SAE 10W-30 (API SE, SF, SG, SH or higher recommended)
Brake Fluid Type:
DOT 3 or DOT 4 brake fluid (for drum brake systems, typically mineral oil is not used, confirm with manual for specific brake type if hydraulic is present).
Common Wear Items:
Tire wear, brake pad/shoe wear, chain and sprockets, spark plug fouling, carburetor needle wear.
Carburetor Issues:
Clogged jets, vacuum leaks, improper idle adjustment leading to rough running.
Engine Starting:
Difficult starting can be due to fuel issues, ignition problems, or improper carburetor settings.
Suspension:
Fork seals can leak over time, rear shock absorber may lose damping.
Manufacturer:
Yamaha Motor Company
Heritage Focus:
Long-standing reputation for performance, innovation, and reliability in motorcycles and other powersports vehicles.
Predecessor:
Yamaha PW50, TT-R50 (though TT-R90 introduced a slightly larger displacement for growing riders).
Key Design Changes Around 2001:
While the core design remained consistent, minor updates in graphics, plastics, and potentially carburetor jetting may have occurred around this period.
Production Years:
Circa 2000 - 2007
Manufacturing Location:
Japan (primarily)
Industry Recognition:
While specific awards for the TT-R90 are not widely publicized, it is recognized as a popular and reliable entry-level off-road motorcycle by enthusiasts and riding schools.
Owner Satisfaction:
Generally high due to its durability, ease of use, and low running costs.
Emissions Certification:
Typically meets US EPA standards for off-highway recreational vehicles of its era.
