I have a 2007 Kawasaki Ultra LX with 30 hours which I have just purchased. I weight 110kg's (250 pound) and my daughter is only 45kgs(very small). The Ski's top speed is only 72 klm (45m/h) surely this should go a lot faster with than this. Is the weight a big factor ?? the tank was only half full as well. And what should it do speed wise, and what should I look for if it is a fault??