Evinrude 50hp - Rust on Top Spark Plug

[Kiwi]

After a few months sitting in the shed when I went to start my '73 50hp Evinrude (50372r) it would not fire and sounded like it was turning over slower than usual on the starter. When I took the upper spark plug out there was rust on it. I cleaned both plugs with a wire brush. The next try it burst into life. I've run it in a tank to warm it up and last weekend took it to the lake and its running fine. However I'm really worried that water is getting inside or could it just be condensation (I'm doubtful on that though)

Any suggestions ?
Thanks

 

[boobie]

Re: Evinrude 50hp - Rust on Top Spark Plug

Do a compression test on it. If that's okay, run it.