The 1997-98 RS 125 keeps the 1995-style bodywork with three-spoke wheels, aluminium twin-spar frame and 40 mm upside-down fork.
| MODEL | APRILIA RS 125 1997 - 1998 |
| Year | 1997 - 1998 |
| Engine Type | Single cylinder, two-stroke, reed valve (Rotax 123 listed for 1997, Rotax 122 for 1998) |
| Displacement / Capacity | 124.8 cc / 7.6 cu in |
| Bore X Stroke | 54 x 54.5 mm / 2.13 x 2.15 in |
| Compression Ratio | 12.5:1 |
| Cooling System | Liquid cooled |
| Max Power | 1997: 23 kW / 31.3 PS @ 11500 rpm; 1998: 18 kW / 24.5 PS @ 10500 rpm (also quoted as 25.4 kW / 34 hp @ 11000 rpm) |
| Max Torque | 1997: 20.4 Nm / 15.0 lb-ft @ 10800 rpm; 1998: 17 Nm / 12.5 lb-ft @ 9500 rpm |
| Ignition | — |
| Induction | 1997: Dell'Orto VHSB 34 LD carburettor; 1998: Dell'Orto PHBH 28 BD carburettor |
| Start System | Electric |
| TRANSMISSION SPECS | |
| Lubrication | — |
| Gear Box | 6 Speed |
| Clutch | Wet multi-plate |
| Final Drive | Chain |
| CHASSIS SPECS | |
| Frame | Cast aluminium twin-spar (bridge) frame |
| Front Suspension | 40 mm upside-down fork, non-adjustable, 120 mm / 4.7 in travel |
| Rear Suspension | Aluminium swingarm, single shock with linkage, adjustable preload, 120 mm / 4.7 in travel |
| Front Brakes | Single 320 mm floating disc, 4-piston axial caliper |
| Rear Brakes | Single 220 mm disc, 2-piston caliper |
| DIMENSION SPECS | |
| Overall Length | 1960 mm / 77.2 in |
| Overall Width | 780 mm / 30.7 in |
| Overall Height | 1090 mm / 42.9 in |
| Seat Height | 810 mm / 31.9 in |
| Wheelbase | 1345 mm / 53.0 in |
| Ground Clearance | 135 mm / 5.3 in |
| Dry Weight | 115 kg / 253.5 lbs |
| Wet Weight | 144 kg / 317.5 lbs |
| WHEEL SPECS | |
| Front Tyre | 110/70-17 |
| Rear Tyre | 150/60-17 |
| FUEL SYSTEM | |
| Fuel Capacity | 13 Litres / 3.4 US gal (incl. 3 L reserve) |
| Fuel Consumption | — |
| Top Speed | 1997: 151 km/h / 93.8 mph; 1998: 155 km/h / 96.3 mph |
The 1997-98 RS 125 keeps the 1995-style bodywork with three-spoke wheels, aluminium twin-spar frame and 40 mm upside-down fork. The changes were mostly in the engine bay: outside Italy the older Rotax 123 stayed in use until about 1997 before the revised Rotax 122 took over, and German data for 1998 shows a smaller PHBH 28 carburettor with a lower listed output. With Biaggi gone to Honda his colours were dropped, and Harada and Rossi replica schemes were offered from 1998.
