yamaha started making 4 stroke outboard motors in 1976.
when did yamaha start making 4 stroke outboard motors?
1976
although four stroke outboards have been sold since the late 1920s, particularly roness and sharland, in 1962 homelite introduced a commercially viable four cycle outboard a 55-horsepower motor, based on the 4 cylinder crosley automobile engine. this was called the bearcat that was later purchased by fischer-pierce who are the makers of boston whaler for use in their boats because of their advantages over two strokes. in 1964, honda motor co. introduced its first four-stroke powerhead. in 1984, yamaha introduced their first four-stroke powerhead. these motors were only available in the smaller horsepower range. in 1990 honda released 35 hp and 45 hp four-stroke models. they continued to lead in the development of four-stroke engines throughout the 1990s as us and european exhaust emissions regulations such as carb (california air resources board) led to the proliferation of four-stroke outboards. at first, north american manufacturers such as mercury and omc used engine technology from japanese manufacturers such as yamaha and suzuki until they were able to develop their own four-stroke engine. the inherent advantages of four-stroke motors included: lower pollution (especially oil in the water), noise reduction, increase fuel economy, and increased low rpm torque.
outboard motor
the union internationale motonautique (or "uim", headquartered in europe) sanctions many different hydroplane categories of hydroplane powerboat racing. international uim f-125, f-250, f-350 and f-500 circuit powerboat races are very popular in europe, asia, and the united states. uim's o-series hydroplane formula circuit racing events are some of the most prestigious professional racing outboard (pro) hydroplane events in the world. national powerboat racing teams compete for national and international titles in these hydroplane racing circuits. the american power boat association (apba) sanction similar pro class national title events in the united states. professional f-series world cup title powerboat races are held at europe, united states, and western asia race site locations every year. equivalent apba pro classes are 125cch (uim o-125), 175cch (uim o-175), 250cch (uim o-250), 350cch (uim o-350), 500cch (uim o-500), 750cch (apba only), and 1000cch classes. pro classes using 500cc and larger displacement racing motors must be equipped with an enclosed re-enforced capsule, a certified racing harness restraint system, and a self-contained oxygen system for the driver. the faster classes of pro hydroplanes (with straightaway speeds from around 75 to 120 miles per hour) use 2-cycle outboard motors running highly filtered methanol race fuel mixed with a pure castor or synthetic castor-based lubricating oil. all methanol-fueled and gasoline-fueled pro racing outboard motors are direct drive (no gear reduction) and equipped with high performance, motorcycle racing style magneto ignition and carburetor systems. 125cc through 1000cc pro series hydroplanes are not entry level classes in outboard powerboat racing. investment costs are moderately high compared to similar apba stock and modified outboard racing classes. k-pro (an apba entry class) is the only pro hydroplane class running modified, recreational outboard motors; all other pro hydroplane classes use 2-stroke outboard motors designed and manufactured specifically for pro circuit racing purposes. entry level classes for the pro series classes are gasoline-fueled k-pro (apba sanctions only) and osy-400 (sanctioned by both uim and apba.) international uim teams have a formal crew that usually consists of family members, motor mechanic, hull builder sponsor, and owner/driver team in order to be successful at racing international f-125 through f-500 circuit hydroplanes. some hydroplane hull builders sponsor more than one team in a formula series circuit. pro outboard hydroplane hulls are constructed with lightweight wood, composite, and hybrid (wood/composite/aluminum) materials. outboard performance craft hydroplanes (sometimes called "tunnel boats") are a different racing series of uim and apba outboard powerboat classes. limited hydroplane racing classes are inboard-engine powered boats that use high performance gasoline fuel.
hydroplane racing