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Motorcycle R&D Center, Honda R&D Co., Ltd.New Mid Concept Series Development Project

Key technologies that make the New Mid Concept Series the most fuel-efficient crossover bikes in their class

●Stoichiometric combustion at low engine speeds, including idle
 Numerous strategies for improving the fuel economy of motorcycle engines have been tested, especially in small models. Such strategies include ●improving combustion efficiency, ●reducing internal resistance, and ●eliminating wasteful fuel use. However, ●achieving stoichiometric combustion at low engine speeds, including idle was a major factor contributing to the success of the New Mid Series in becoming the most fuel-efficient of large sport-touring bikes, and was the first such achievement in a large Honda motorcycle.
●Delivery of the optimum ratio of air and gasoline
 Burning gasoline under ideal conditions—in other words delivering air and gasoline to the cylinders at an appropriate ratio—is an effective way not only to improve fuel efficiency but also to generate cleaner exhaust gas. This optimum ratio of air to gasoline is called the stoichiometric ratio (optimum air-fuel ratio) ; theoretically this ratio is 14.7 grams of air to 1 gram of gasoline. Developers of the New Mid engine aimed to achieve combustion at this optimum air-fuel ratio (stiochiometric combustion) at all engine speeds.
 In short-stroke, high-revving engines, which have been mainstream in conventional large motorcycles, engine speed tends to stabilize more easily when stoichiometric combustion takes place at low speeds close to idle. As a result, these engines have been typically tuned to a richer (lower) mixture of air to fuel, which tends to make fuel efficiency worse.
 Engines in the New Mid series have a longer stroke and experience peak power at low engine speeds. This, coupled with modifications to the shape of the combustion chambers, valve timing, and other areas, allowed Honda to achieve stoichiometric combustion at low engine speeds—the first for a large Honda motorcycle engine—and achieve the best fuel economy among large crossover bikes currently on the market.
●Achieving the highest fuel economy (27.9 km/L, WMTC test cycle (see note)) while retaining power performance equivalent to motorcycles in the same class at everyday speeds
 Developers of the New Mid Concept Series set a numerical target of 27.0 km/L or more, as measured by the WMTC test cycle, to achieve their best-in-class fuel-economy goal. To meet this target, they employed a number of friction and weight reduction technologies in the engine.
Note: The WMTC test cycle is used in Europe for motorcycle emissions and fuel efficiency certification. It more closely simulates actual riding conditions compared to the test cycle used in Japan (constant speed of 60 km/h on a flat surface).

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