Introduction

Sport scooter of the second generation with liquid cooling

The model "Aprilia - SR 50 Stealth (LC, 1997, ZD4MZ)" is a sporty 50 cc scooter from 1997 and part of the second generation of the SR 50 series.
With the "Stealth" designation, Aprilia introduced a version featuring a striking new design and, for the first time, factory-installed liquid cooling.
It was aimed at young riders looking for a scooter that combined a sporty appearance with enhanced performance and modern everyday usability.

Model history

Second generation with technical upgrades

The SR 50 Stealth (ZD4MZ) marks a turning point in the history of the SR series: starting in 1997, the model received a major overhaul including a new frame, revised bodywork, and a liquid-cooled engine.
The name "Stealth" stood for a more angular and dynamic look that clearly distinguished it from earlier versions.
This generation ushered in a new era in the 50 cc sports scooter segment, offering technical features previously reserved for premium models.
The SR 50 Stealth entered a growing competitive market with rivals from Yamaha, Peugeot, and MBK also offering performance-oriented 50 cc scooters.

Technical details

Engine and performance

The Aprilia SR 50 Stealth (1997, LC, ZD4MZ) is equipped with a liquid-cooled single-cylinder two-stroke engine with a displacement of 49 cm³.
Thanks to liquid cooling and an improved intake system, the engine delivers better thermal stability and more power reserves compared to earlier air-cooled versions.
Output is around 3.4 kW (approx. 4.6 hp), with a restricted top speed of about 45 km/h depending on local regulations.
Power is transmitted via a continuously variable CVT automatic transmission for smooth acceleration and easy operation.

Chassis and brakes

The chassis is based on a newly developed frame offering improved rigidity and handling.
At the front is a telescopic fork; at the rear, a single shock absorber ensures adequate damping.
The braking system was significantly upgraded compared to earlier models: a 190 mm front disc brake and – for the first time – a rear disc brake provide excellent stopping power.
With a dry weight of approximately 92 kg and a wheelbase of around 1,285 mm, the Stealth remains agile but offers more stability than the first generation.
Tyres in size 130/60-13 emphasize the sporty character and ensure good grip.

Design and variants

Striking appearance with "Stealth" character

The SR 50 Stealth featured a unique body design with sharp lines, integrated indicators, and aerodynamic fairings.
Typical color options included black, silver, blue, and red combinations, often with bold "Stealth" lettering and racing-style graphics.
The model was exclusively available with liquid cooling and thus clearly stood apart from the still-offered air-cooled standard version.
No official limited or special editions are documented for the 1997 model year – customization was usually achieved through aftermarket parts and accessories.
The SR 50 Stealth was sold in many European markets and remains a popular model among scooter enthusiasts to this day.