Good afternoon Gentlemen!

I�ve just finished putting my (formerly) trusty old Stihl FS 36 back together after cleaning the carburettor, and I couldn�t help noticing that the Fuel Cap on my machine doesn�t appear to have a vent-hole in it�

So, the obvious question that begs is - If the Caps on these units don�t have a hole in them, how are their Fuel Tanks managing to breathe?

Just as an odd aside - the underneath of the Cap looks a little like a Cap would normally look if it was going to have a vent-hole on top somewhere, even though there isn't one(?)

Many Thanks in advance,
Mike.