The F90 is equipped with a four-cylinder 16-valve in-line SOHC 1.8L engine, bigger displacement than the previous generation 1.5L engine it replaces. Most impressively the bigger F90 weighs in close to 10kgs lighter than the old engine (F90LB: 162kg / F90XB: 166kg). This remarkable achievement means improved performance, and better balance when fitted on hulls in this category. The F90 is based on the F115B’s four-cylinder power unit. The F90’s reduction in weight and improved compactness is achieved by adopting a single overhead camshaft design (SOHC), actuating four valves per cylinder. This unique valve train design was first seen in Yamaha’s award-winning F70A, one of the most popular engines in Australia. This design allows the F90 to achieve the weight savings of a single camshaft while still achieving the smooth and efficient performance only seen in 16 valve, four-cylinder engine of this size.