Yamaha Outboards 115HP VMAX SHO VF115XA. The I-4 V MAX SHO 115 is Yamaha’s fastest 115-hp four stroke, ever, with a top speed of nearly 51 mph.* On top of its impressive speed, it features tech unheard of in its class, including a long-track intake system, free-flow exhaust and knock sensor. Still it’s 10 pounds lighter than a competitor’s two stroke.