Four Stroke Series - Midrange Features & Benefits Multi-Port Precision Electronic Fuel Injection, on the F50 and up, delivers the optimal fuel/air mix to each cylinder for easier starting, faster acceleration, and better fuel economy. Single throttle valve is a simple, lightweight design allowing for quick and easy adjustment. The air silencer box on the F75 and F90 reduces intake air noise to a minimum with the use of a highly pourous nylon cloth that soaks up the niose making these engines whisper quiet while the surge tank reduces air turbulence for smoother operation. Composite Intake Manifold - The long tube intake tracks are tuned to increase air flow increasing low end and midrange torque performance resulting in a more powerful hole shot and increased acceleration. The air silencer box reduces intake air noise while the surge tank reduces air turbulence for smoother operation. Top-Mounted Flywheel keeps sensitive electrical components out of the water. The Microcomputer Ignition, adjusts timing to maintain optimum engine performance, economy and durability under all conditions. Single Overhead Cam on F50 and F60 models, provides a more compact, lightweight design especially important in mid-range four strokes.     Double Overhead Cam Design features fewer moving parts than conventional single overhead design, for greater reliability on F75 and above. The Multi-Function Tiller Handle, optional on F25 through F115, gives you fingertip control of starting, shifting, steering and throttle. Yamaha's Variable Trolling Speed feature, optional on the F50, F60, F75 and F90 tiller handle models, allows the operator to stay on the fish by selecting the preferred rpm, (in 50 rpm increments). Our Three Year Limited Warranty protects every Four Stroke. All Yamaha four strokes exceed Federal EPA 2006 emission requirements. The 50hp and up have earned a California C.A.R.B. three-star rating. The Fresh-water Flush Device enables you to flush the engine without starting the engine. Yamaha's Exclusive YDC-30 Alloy is the most corrosion-resistant base material in the industry. Our Lightweight and Compact DOHC designed F115 received the "Motor Boat and Sailing" award for innovation. Yamaha is Dedicated to Helping create a cleaner environment through advances in outboard technology.