Valve cover - corroded body of the bolt

Hi Team,

I bought my xr650r over 2 years ago, recently i decided to take the valve cover off and clutch basket to get a better look of its health...

Anyway when i took of the valve cover one of the long bolts right hand side (exhaust end) was pretty rusty / eaten up .... it was only one bolt of the many that holds the valve cover... I also had a similar looking bolt at the clutch cover ...

Just wondering what would cause this corrosion when the bolt is nicely sealed inside the head...? all other bolts look good.

Thanks


Pat

Corrosion is water, you go swimming often with your bike?
Clean or renew bolt, then reassemble with some anti seize copper compound.

and be careful tightening the long bolts on the covers - use a torque wrench as they snap easily.