[Smackdaddy53]

Check compression, should be around 125-130 in each hole. Keep the plugs sprayed with CorrosionX along with everything else under the cowling. The bottom plug always gets rusty first if you don’t. Not sure why you have that buildup but compression test and new plugs. Don’t cheap out, buy the NGK that are specified for your motor, they aren’t expensive.

 

[Smackdaddy53]

That head has been removed and not reinstalled properly. Those bolts to hold it in are a mix of SAE SS, factory metric hardware, and it appears to be SAE zinc plated grade 3, 5, and 8...basically a hodge-podge of bullshit.

The heavy corrosion you are seeing at the base of the plugs is from the water jacket cover leaking around the plug locations. Likely, that gasket wasn't replaced along with the head gasket. order both, clean the surfaces, and reinstall. You are relegated to using the hardware sizes now in use (thought they can all be SS) as the SAE ones will have been drilled an tapped.

Good eye!

 

[Smackdaddy53]

Thank you, sir! Engines and corrosion are firmly in the wheelhouse.

I should have noticed the odd assorted bolt heads. I bet the previous owner pulled the cover and reinstalled and didn’t replace the gasket.

 

[Smackdaddy53]

It is. Roaches and 3-cylinder Yamaha outboards are the only things that remain alive after a nuclear blast.

If nukes were real that would be true! And maybe my ex wife