The RipCurrent S has 750W, but the CrossCurrent S has 650W Why is that?

The has a physically larger motor and as a result can handle more power. It’s also heavier with bigger tires. So it needs a little more power to reach our performance targets. 

The RipCurrent S has a larger motor and, as a result, can handle more power. The bike is also heavier and uses larger tires, meaning that more power is required to reach performance targets.