I have a 1997 gs with the 717 I believe or 720. I cleaned the carb and it ran for about 5 minutes like crap then shut off. Would not start again. Since this has happened I have went through this thing too to bottom. New fuels hoses cleaned and rebuilt the carburetor, checked the fly wheel key the stator the rectifier and made sure the RV was in time. Hooked an external fuel tank up to Mae sure it was getting fuel. The ski has 115 compression both cylinders. It will not start. Has sparks great spark. Has fuel and oil. I don't get it. Spray starting fluid in the carb won't even spit or sputter. Sometimes when cranking it's like it comes to a dead stop tho and thumps. But not like it wants to fire. I'm at a loss here I work on boats on a daily basis and I've never been this lost. Any input would help