I was riding the other day and my Doo was running bad anyhow because I had yet to replace fuel lines and rebuild the carbs. It was running ok and then it lost a lot of power and wouldn't even plane out and I babied it back to the dock. I just figured it was the bad fuel lines dirty carbs. I rebuilt the carbs and changed the fuel lines, took it to the lake today and it wouldn't even move. Came home and checked compression, none on the rear cyl. Should I just start by taking the head off and seeing what I find? Any help or suggestions would be great.