Force 120 l-drive plug fouling

[boaterino]

Having issues starting my force 120 l-drive. I had it running last night after it was warmed up for about 3-5 minutes. Mechanic helped me adjust timing. Ran great in driveway and had new plugs. Took it to water yesterday and after that 3-5 min driveway run and trying to start it in water, first plug was fouled with a grey substance. I recently replaced the exhaust gasket. Is this indicate of water in gas or motor? Maybe needs a head gasket? Is there a way to test the exhaust gasket seal?

 

[jerryjerry05]

Grey gunk, possible exhaust and unburned fuel/oil???
The way I tested my exhaust: get a snake camera and run it through the top piston when
it's all the way back and the ports are open.

Do a compression test.
The timing was it done right?

 

[Redbarron%%]

Sometimes gray gunk is aluminum from a burned piston. I had this problem myself.
Check with a USB camera. compression check etc.