Honda Develops a Powerful, Fuel-efficient 700cc Engine for Midsize Motorcycle

TOKYO, JAPAN – September 26, 2011 – (Motor Sports Newswire) – Honda Motor Co., Ltd. has announced the development of a new motorcycle engine with powerful torque in the low- to mid-speed range and top class, fuel-efficient environment performance, along with a second-generation Dual Clutch Transmission. This new engine is a liquid-cooled, 700cc, 4-stroke, in-line, 2-cylinder engine that fits into the mid-class range (displacement between 500 and 750cc) popular in Europe. Fuel economy exceeds 27km/L, (1) best in the mid-class range, and achieves an approximate 40% (2) improvement over other sports models in its class.

This new engine can be coupled with a newly developed lightweight, compact second-generation Dual Clutch Transmission, featuring a smooth, direct feel and excellent transmission efficiency, in addition to a 6-speed manual transmission.

This new engine will be mounted on three models based on different concepts, which are slated for exhibition at EICMA2011 (69th International Motorcycle Exhibition) to be held in November in Milan, Italy.

Honda developed this new motorcycle engine in order to realize a set of motorcycles based on its new concept of offering outstanding fuel efficiency in the mid-class while delivering powerful, throbbing torque in the normal range for touring and urban riding.

Development was performed to meet these requirements:

  • An engine that is easy to handle with plentiful torque in the range normally used, and which also delivers a pleasant, throbbing feel during sporty rides
  • Top-class, fuel-efficient environmental performance best suited for the next-generation mid-class engine
  • A lightweight, compact design that allows more freedom in the body layout and – provides highly convenient space

Honda determined the engine layout after examining a variety of engine types from numerous perspectives and decided on an in-line, 700cc, 2-cylinder engine with a 62 degrees forward lean (cylinder assembly angle). To meet a wide variety of uses, two transmissions can be coupled with this engine: the second generation of Honda’s innovative Dual Clutch Transmission, and a 6-speed manual transmission.

Main Features of the New Engine

I. Higher combustion efficiency and lower friction

A wide variety of low friction technologies that aid better fuel economy are incorporated: To improve fuel efficiency through better-controlled combustion while realizing a powerful ride in the low- to mid-rpm ranges, the bore-stroke ratio is set at 73 x 80mm. An ideal combustion chamber shape and optimum valve timing also contribute to achieve stable combustion. Resin coating is applied to the pistons, and lightweight aluminum material is employed for the first time in a motorcycle in the friction-reducing roller rocker arm.

II. Uneven-interval firing and uniaxial primary balancer

Adoption of uneven-interval firing with a 270 degrees phase crank and uniaxial primary balancer help realize an engine with a pleasant throbbing feel that also reduces vibration.

III. Branch intake port inside the cylinder head, valve timing

The layout of a branch intake port inside the cylinder head was chosen to have only one intake channel for two cylinders. This design creates deliberate interference between the two cylinders’ intake processes to achieve precisely calculated changes to combustion timing.

In addition, to change the valve timing between the two in-line cylinders with one camshaft, the specifications provide for a cam with two timing routines for the intake valve. Through these measures, subtle combustion changes can be generated to give the engine a delightful, pulsating feel.

IV. Exhaust emission purification system

V. Second-generation Dual Clutch Transmission

The Dual Clutch Transmission, developed for the first time by Honda for motorcycles and installed on the VFR1200F, is now lighter and more compact through a simplified hydraulic circuit and other design enhancements. A learning function has been added to each selected running mode to detect a variety of riding environments from city streets to mountain passes and automatically performs the most suitable shift control. Although it is an automatic transmission, the Dual Clutch Transmission delivers fuel economy on a par with manual transmissions as a result of its excellent transmission efficiency.

(1) WMTC mode (Honda calculations)

(2) Honda calculations

(3) PGM-FI (Programmed Fuel Injection System) is a Honda registered trademark

(4) Honda calculations

About Honda

Honda Motor Co., Ltd. is one of the leading manufacturers of automobiles and power products and the largest manufacture of motorcycles in the world. Honda has always sought to provide genuine satisfaction to people worldwide. The result is more than 120 manufacturing facilities in 30 countries worldwide, producing a wide range of products, including motorcycles, ATVs, generators, marine engines, lawn and garden equipment and automobiles that bring the company into contact with over 19 million customers annually. For more information, please visit http://world.honda.com .

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