In 2004, the ET4 was one of the two entries of the ET Series of scooters released by Vespa, a subsidiary of Italian auto manufacturer Piaggio; the other entry was called the ET2. Indeed, the 2004 models share several components. The 2004 Vespa ET4, however, was designed and marketed as the more advanced version of the two.
The main distinguishing factor of the 2004 Vespa ET4 is its engine, which is a four-stroke single-cylinder (thus the number “4” as part of the scooter’s designation). It displaces at 150 cubic centimeters and generates 11.26 horsepower. Using a single overhead camshaft configuration, the engine has two intake valves on its lone cylinder. The bore and stroke of the engine are measured at 2.5 by 1.9 inches (63 by 49 millimeters), and the compression ratio is 11.1 to 1. A carburetor is in place for blending air and fuel for the engine, and drivers can choose to start the engine with the manual kick starter or electric starter provided by Piaggio.
Each engine on the 2004 Vespa ET4 is hooked up to a Continuously Variable Transmission, or CVT. The main advantage of this automatic gearbox is the ability to shift through an unlimited number of gear ratios for the increased efficiency of the engine. The end result is a significantly improved fuel economy. Like its ET2 counterpart, the 2004 Vespa ET4 comes with a 2.4-gallon (9-liter) gas tank. Piaggio recommends premium fuel for optimal performance of the scooter.
Each 2004 Vespa ET4 is made of steel, a material employed to give the scooter its sturdy structure. Parts adorning, covering, or protecting the bike include front and rear fenders, fork guard, and side cover. Piaggio gives the 2004 ET4 a center stand for the convenience of parking the scooter anywhere. The seat, a one-piece vinyl unit, provides enough space for the rider and just one passenger. Digital instrumentation at the front of the scooter consists of a clock, speedometer, and fuel level warning gauge. For storage, the ET4 has a rear rack and lockable under-seat and helmet compartments. Also included are a halogen headlight and a pair of rearview mirrors for increasing visibility, particularly for blind spots or night time.
Each 2004 Vespa ET4 uses a 7.9-inch (200-mm) front hydraulic disc brake and a 4.3-inch (110-mm) rear drum brake for its braking ability. This gives it an advantage over scooters that use all-drum brake layouts. Its suspension, instrumental for absorbing bumps during driving on rougher terrain, comprises a tie rod made of steel at the front and a single-sided swing arm at the rear of the scooter.
The 2004 Vespa ET4 shares some of the physical measurements of its less powerful ET2 counterpart. It has a 69.4-inch length, 26.4-inch width, and 50.4-inch wheelbase, with a seat height of 31.7 inches. Also, like the 2004 ET2, the 2004 edition of the ET4 has 10-inch aluminum wheels and tubeless Pirelli® tires. However, at 236 pounds, the ET4 is 20 pounds heavier.
The sibling of the 2004 Vespa ET4, the 2004 ET2, shares the same attractive features: a lightweight yet strong build, good fuel economy, and satisfactory engine power. However, for an upgrade of the ET2, particularly for its power, it is recommended to bump up to the ET4.