was running across the lake at 5800 rpms lost rmps motor shut down heard a knocking noise pulled spark plugs today one plug look like it was melted just wanted to confirm what i think happen.

If you pull a spark plug and find a flat electrode or melted metal you have a problem. It could be as simple as a thrown piston ring that has thrashed one cylinder. If your's did what happened to my Engine when it knocked to a hault and stoped running before I could get out of the gas... it has detonated and took aout all six pistons/ cylinders.

Have a Certified Outboard Mechanic look at it... Good Luck!

Detonation.

Not good. What kind of motor? low octane or old fuel, water in fuel, oil injection problems, heat and timming all can cause an outboard to self destruct. A lot has been said about problems from not letting the outboard warm up enough before taking off and adding a large water seperator filter because of our fuel now days.

If that is silver metal on the spark plug.....Bad ju-ju. piston melt down....knocking? Better hope that a bearing did'nt give up. If it did,,,,there went the crank and a rod to boot.......(PS. You were problably fishing my spot on OH Ivey)