how does water get into a cylinder?

[BottomLine]

Yamaha has acknowledged problems with the 300 HPDI's on the back of Contenders. Water escapes from the transom bait well and makes it way into the air intake of the motors. Yamaha has since come out with a "Water Intrusion Kit" that your authorized Yamaha dealer will install under warranty. Also make sure your motor is not mounted too low. Not related to water, there was also an updated oil pump kit that Yamaha released. You must not use old gas that has not been properly stabilized and keep up with your filters. Remember you are squeezing 300 HP from a motor that 2 guys can lift and carry. It's vital that you maintain the motors & filters, watch your gas and most importantly, make sure they run 5500 rpms wide open, and run them wide open often.