The standard length is M6x25 and the longer ones (marked in red) are M6x40.
|yellow: M6x16, blue: M6x48 but with M8-shaft|
The starter solenoid cover is held on with one M6x16, one M6x25 and one M6x70.
The clutch adjuster cover is held on with one M6x16 and one M6x55.
I know this is probably a somewhat unexciting post, but if you like me tried to work out which bolt goes where and what size/length it is, this may eventually come in handy.