I have a gen V 502. Over the winter I had my starboard motor rebuilt and the port motor tuned up with new plugs, rotor, cap and plug wires. Port Motor now has a loud knock to it. Any ideas? Thanks

crossed plug wires.. go over the firing order..

Checked plug wires, they are correct. I did find water oil mix on inside of valve covers, but not on dip stick.

rotor not pushed down all the way?

you did use a mr43t plug rite??? make sure you did not use a ts plug,,it has a extended tip..then their are longer plugs that will screw in and hit the piston..

I will have to check. I had a marine shop do the tune up while my other motor was getting rebuilt,