crankcase breather attached to a catch tank?
Someone who knows what they are talking about will be along soon....

Correct mate-crankcase breather.

John

Why is mine just black plastic then? Is there any gain (apart from looks) to changing it?

None ... unless you're Casoli :D

ouch but true, it should gain you 4bhp, and there should be less gyroscopic forces interfering with the giggling pin which in turn will balance the weight on the thrutchet grunger. I have 3 fitted to my bike.:P