Honda has developed GX690/GXV690, a small, high-performance, air-cooled, 4-stroke V-twin cylinder general purpose engine with an outstanding environmental performance.In this new model, the enhanced shapes of combustion chamber and port, upgraded cooling capability around the combustion chamber, and variable ignition timing effectively suppress knocking, while increasing the compression ratio to 9.3 from 8.3 of previous GX670/ GXV670, which results in 8% increase in output. Without using any catalysts, this engine with 10% of increased fuel efficiency has cleared the EPA exhaust emissions regulations. Both the decreased size of air cleaner, which was resulted from enhanced filter, and the adoption of oil filter base, which also had an oil cooler function, eliminating previous oil cooler, allowed us to reduce the total height and width of the engine, as well as the volume by 18%. The modified shape of cooling fan and fan cover, configuration of muffler, and other parts are effective to decrease the measured and perceived noises that occurred in the previous engine in operation.As new features, we have also added an hour meter and oil alert indicator to enhance the usability of engine. Furthermore, we advanced battery charging performance to offer a diverse use in working machines.
Article of Honda R&D Technical Review Vol.21 No.2 (49 - 56)