suspicious rust on bolt

[pstephens46]

should not be any salt water under cowling, newer run it without cowl.
the only salt water is inside cooling passages.
all Yamaha bolts, they are all stainless steel, should not be any rust.
but again, some of my hardware (stainless steel) on deck leaking rust
other bolts ok, no rust (see pic).
central electrode on this spark plug looks whiter, then rest, may be exhibiting sign of lean mix or water in combustion (third plug from left, i.e. cyl #2)
i have not used compression tester yet, but it is possible that high pressure gases in combustion chamber leak into cooling and push water past bolts?
all this stuff works in mysterious ways
will clean and control it, head gasket may be in order
thank for pointing for cracked thermostat rubber, will fix it.

Some salt always makes it way inside cowling. I rinse my engine lightly to remove it. Nice white crust on plastic covers....

[amahaork]

Yes it was rust
Yamaha not using stainless head bolts (with washers), they are nickel plated.
When reused, contact scratched and metal exposed to water.
I wash it with fresh water, sprayed everything with WD-40, let it seat dry and sprayed with lithium.
Thank you all.
Out.