02 150hp vmax knocking

[Bchildree]

I was out on the water the other at about 3/4 throttle when my buddy heard a knocking sound. I immediately got off the throttle and after 30 seconds or so cut it off and used my trolling motor on the way back. When it not in gear it’s almost not notisable, but once in gear it is very audible, and increases with throttle. It seems crazy for it to be blown up. The gentleman who owned it before me took insanely good care of it and it has pretty low hours for its age. The 2 stroke oil resivoure was almost full and it was still pissing water.

 

[rejesterd]

Maybe valve clatter. Try removing all the spark plugs and turning the flywheel by hand to see if you can hear/feel the knock. You might be able to narrow it down to a specific cylinder/valve pair. Or do a leak down test. If the leak down test confirms that air is leaking out of one of the vales when it shouldn't be, then you have to remove the valve cover and see what's going on.