<P> 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 technical superiority and efficiency 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 , increased low end torque , and smoother operation . </P>
<P> 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 technical superiority and efficiency 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 , increased low end torque , and smoother operation . </P>
when did yamaha start making 4 stroke outboard motors
when did yamaha start making 4 stroke outboard motors
1984
1984