The 503 is another well respected two-cycle engine by Rotax. The earliest reference to this engine I can find is 1986. The aircraft version was introduced in 1990.

models

• 503 UL DCDI: 50 hp (37 kW)

specifications

• In-line, two-cylinder piston engine
• Displacement: 30.3 cubic inches (496 cc)
• Bore x stroke: 72 x 61 mm