Rivera Primo® has championed the British SU® carburetor in modified form for the Harley motorcycle for over 40 years, in fact that's how the original Rivera Engineering® got started in the motorcycle industry! The SU® provides smooth, even power and torque throughout the entire power band, with excellent cold-start characteristics, and drive-ability. Although originally intended for automobile use, the SU® carbureter has proven to be unmatched in performance when adapted for use on a carbureted American V-Twin. The SU® gives added potential over the entire rpm range, where other carburetors fail to perform. In the 70's a documented comparison of all after-market carburetors against Rivera Primo's® now famous SU® conversion, the SU® easily dominated the field and things have not changed much in the land of carburetion since then. A comprehensive look at the Eliminator® SU® and it's features will give some insight as to why the SU® works so well with the Harley V-Twin. A wide margin of superiority means you will realize more power, at the same time attain significantly improved mileage with this very popular carburetor conversion.
Of the many beneficial features of the SU®, the variable Venturi is the most profound. Most carburetors are designed and operate with a fixed Venturi. The venturi creates a low pressure area at the main jet. This in turn pulls fuel through the jet, which atomizes as it is delivered into the airstream. The amount of air drawn through a fixed Venturi is directly proportional to motor speed. As air velocity varies, so does the "low" pressure area, and its ability to extract and atomize gasoline in an efficient manner. To offset this deficiency in other carburetor designs, many compensating or multi-jet devices have been tried in an effort to minimize this negative aspect of the fixed venturi. The unsuccessful results are history. While some are designed around the variable Venturi design, the Rivera Primo® Eliminator® II conversion is the most efficient manifestation of this principal. With the Eliminator® II, fuel/air requirements of the motor dictate Venturi size, which increases automatically as demand increases. The resulting constant velocity maintains a relatively stable low pressure area over the main jet for maximum fuel extraction, and optimum fuel atomization. The result is superior throttle response at all rpms, better fuel economy, at the same time efficiency is improved meaning more horsepower and torque available to the rider.
The Rivera Primo® Eliminator® II SU® carburetor has been designed to exploit the advantages gained by containing the main jet, and float chamber in a common concentric housing (the domed chamber), which results in a carburetor that is especially beneficial to a carbureted VTwin motor. This concentric float is not easily affected by inertial forces as the motorcycle lean while turning, while starting and stopping. The Eliminator® II SU® carburetor from Rivera Primo® is an extremely consistent carburetor, and the concentric float adds to it's predictability. Another outstanding feature of the Eliminator® II is the sophisticated function, yet simple design of its fuel viscosity compensation device. Fuel viscosity affects air / fuel mix. Fuel viscosity is directly related to ambient air temperature, and with the Eliminator® II, a bi-metallic lever is immersed in the contents of the float bowl. Even small variations in temperature adversely affect the mix in a standard carburetor. The Eliminator® II compensates for minute changes in air temperature by moving the main jet, via the bi-metallic lever. This movement actually tunes the air / fuel mix in a very beneficial manner. For further consistency, the jet-needle is retained in the correct position by a spring. No other carburetor is endowed with the features, sophistication, consistency, predictability, and tuneability of the Eliminator® II SU® from Rivera Primo®. The result is unequaled performance, economy, and reliability. The Eliminator® II has been, and continues to be the only real state-of-the-art carburetor for your American V Twin motorcycle.
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