Aprilia STX 125

Make Model	Aprilia STX 125
Year	1984
Engine	Two stroke, single cylinder
Capacity	124 cc / 7.6 cu in
Bore x Stroke	52.8 mm x 57mm
Compression Ratio	14.5;1
Cooling System	Liquid cooled
Induction	Ø28 mm Dell'Orto PHBH AS
Ignition	Electronic
Starting	Kick
Clutch	Multi-disc oil bath
Max Power	13.8 kW kW / 18.5 hp @ 8000 rpm
Transmission	6 Speed
Final Drive	Chain
Frame	Double cradle tubular steel
Rake	28.5°
Trail	87 mm / 3.4 in
Front Suspension	Marzocchi Ø32 mm fork, non-adjustable
Rear Suspension	Swingarm with single shock absorber
Front Brakes	Single Ø240 mm disc
Rear Brakes	Ø160 mm Drum
Front Tyre	100-90 -16
Rear Tyre	100-90 -18
Dimensions	Length: 1370 mm / 53.9 in
Seat Height	800mm / 31.5 in
Dry Weight	113 kg / 249 lbs
Top Speed	130 km/h / 81 mph

Overview

Presented at the Milan Show in November 1983, and marketed from March 1984 Aprilia was now moving forward to the limit in this category: more powerful and more beautiful than the ST 125 from which it derives directly, the STX immediately became a bestseller.

The STX immediately presents itself as more mature and not only for the presence of the windshield and front toe. The pearl white with red and black inserts is certainly modern and the comfortable saddle is now enhanced with the Aprilia logo on both sides. The oil tank is immediately in front of the headstock and the plug is easily accessible, being located just before the petrol cap.

The instrumentation is the same as with the ST. The electric controls are now Italian (CEV) manufactured, although, in the opinion of the writer, are perhaps a little less pleasant than the Magura previously installed on the TS.

Engine

The ST's Hiro engine remains virtually unchanged. According to data collected at the time, it gain in terms of power output is about 0.5hp or 18.48hp at 8500rpm instead of 18.07hp to 8250rpm. Not bad considering the limited interventions and the fact that the mixer "eats" a little more 'power.

More radical, however, assistance where all transmission gear ratios have been lengthened and decreased the secondary reduction ratio and in sixth, from 1:8.04 to 1:7.77; the maximum speed however, due to increased power and new gear ratios increased from 126.8 to 129.7 km / hour.