I thought stainless steel didn't rust... on the left side of my bike, just behind the primary (towards the inside of the engine block) there is a single bolt in there that is all rust. Is this typical of said bolt? (I know, I know, this thread is useless without pics... If needed, I will post one.) I'd like to know how to clean this up (cannot have rust on my Harley!) If I replace it, is this common in that it will just do it again? Will a chrome cap protect it?

 

Yep, stainless steel will corrode. It is just stain-less.
A completely rusted head on a stainless bolt is unusual however.
The discoloration you are seeing may be just a "patina" and not
corrosion.

Bluing and rust remover from a gun shop will remove the rust
but some discoloration will remain.

 

A chrome cap will hid it (the rust)... I painted mine black.

 

What does that bolt go to? Is it easy to take out to clean up & paint?

 

Stainless steel will rust. What makes you think the bolt is stainless? Check it w/ a magnet--bet it's chrome-plated steel.

 

Battery leak?

 

I don't know... I sprayed some rattle can paint into the cap and used a small brush.

 

It's not chrome though...

 

Sorry, an assumption on my part, as the OP mistook it for stainless. There are many steel coatings and platings in everyday use. Anyway, most common stainless steels are virtually non-magnetic, thus EZ to ID w/ a magnet (my point). If the magnet easily attaches itself, then it's steel.

 

Oh, okay. I'll check it out. So if it's magnetic, it CAN rust?