I have a 2005 Polaris Sportsman 700 EFI that has a knocking noise that bothers me because i know knocking leads to bad things (and expensive repairs). Whenever i ride it for a long stretch running around 50-55 mph or punch it and hold it for a good stretch a knocking noise comes from the engine. When i slow down to a stop it becomes much louder, but if i turn the atv off and back on the knocking goes away. Any help or suggestions appreciated.