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MotoLibrary Score
48/100Balanced
Power/Weight
0.33 hp/kg
Top Speed
160 km/h
Engine
125 ccm
Technical Overview
1998 Yamaha ST 125 Technical Analysis & Specification Breakdown
Positioned in Yamaha's sport motorcycle lineup, the 1998 Yamaha ST 125 features a 125 cc (7.6 cu in) liquid-cooled single cylinder, two-stroke configuration. In factory specification, peak output is rated at 36 HP (26.3 kW), transferring power to the rear wheel through a 6-speed gearbox and chain final drive. With a specific output of 288 HP per liter, the engine character is placing it firmly in high-revving supersport territory where top-end breathing dominates.
On the scales, the ST 125 measures 110 kg (243 lbs) dry, translating to a power-to-weight ratio of 0.33 HP/kg (3.06 kg per horsepower). The 10-liter (2.6 US gal) fuel tank paired with a rated consumption of 8 L/100 km provides an estimated theoretical range of roughly 125 km (78 miles) between fill-ups, while factory top speed is listed at 160 km/h (99 mph).
Specific Output
288 HP/L
Power-to-Weight
0.33 HP/kg (3.06 kg/HP)
Theoretical Range
~125 km (78 mi)
Engine
Displacement125.0 ccm (7.63 cubic inches)
Engine TypeSingle cylinder, two-stroke
Engine DetailsSingle cylinder, two-stroke
Power36.0 HP (26.3 kW))
Fuel SystemCarburettor. Mikuni
Fuel ControlPort control
Ignitionelectronic
LubricationOil injection
CoolingLiquid
Max RPM11000
Transmission
Gearbox6-speed
Final DriveChain (final drive)
ClutchWet plate
Performance
Top Speed160.0 km/h (99.4 mph)
Fuel Consumption8.00 litres/100 km (12.5 km/l or 29.40 mpg)
Greenhouse Gases185.6 CO2 g/km. (CO2 - Carbon dioxide emission)
Use this page to compare this motorcycle by its real specifications, not only by model name. Focus on the details that affect fit, comfort, handling, range and ownership.
Power
Compare engine output with similar motorcycles if acceleration, highway use or two-up riding matters.
Weight
Compare weight carefully because it affects low-speed handling, parking and confidence.
Fuel Capacity
Fuel capacity helps estimate touring range and how often you may need to stop.
Brakes
Brake setup is worth comparing if you ride in traffic, mountains or with a passenger.
Suspension
Suspension details can matter for comfort, road feel and long-distance riding.
Transmission
Transmission and final drive affect maintenance, smoothness and everyday usability.
