From 1985 the RX 125 gained a front disc brake in place of the drum, while keeping the rear drum, telescopic fork and monoshock rear end.
| MODEL | APRILIA RX 125 1985 - 1987 |
| Year | 1985 - 1987 |
| Engine Type | Single cylinder, two-stroke |
| Displacement / Capacity | 124.8 cc / 7.6 cu in |
| Bore X Stroke | 54 x 54.5 mm |
| Compression Ratio | 11.5:1 |
| Cooling System | Liquid cooled |
| Max Power | 24.8 kW / 33.3 hp @ 10750 rpm |
| Max Torque | — |
| Ignition | — |
| Induction | Carburettor |
| Start System | Electric and kick |
| TRANSMISSION SPECS | |
| Lubrication | — |
| Gear Box | 6 Speed |
| Clutch | — |
| Final Drive | Chain |
| CHASSIS SPECS | |
| Frame | Steel frame |
| Front Suspension | Hydraulic telescopic fork |
| Rear Suspension | Swingarm with single shock absorber |
| Front Brakes | Single disc |
| Rear Brakes | Drum |
| DIMENSION SPECS | |
| Overall Length | — |
| Overall Width | — |
| Overall Height | — |
| Seat Height | — |
| Wheelbase | — |
| Ground Clearance | 300 mm |
| Dry Weight | 91 kg / 201 lbs |
| Wet Weight | — |
| WHEEL SPECS | |
| Front Tyre | 3.00-21 |
| Rear Tyre | 4.00-18 |
| FUEL SYSTEM | |
| Fuel Capacity | 8.5 Litres / 2.2 US gal |
| Fuel Consumption | — |
| Top Speed | 130 km/h / 80.8 mph |
From 1985 the RX 125 gained a front disc brake in place of the drum, while keeping the rear drum, telescopic fork and monoshock rear end. Its liquid-cooled 125 cc two-stroke made around 33 hp and the bike still weighed only about 91 kg dry, giving it a top speed near 130 km/h and a strong reputation among Italian enduro riders.
