Inner diameter of the valve cover breather hose

[nurms]

I am not currently able to measure the inner diameter of that breather hose. I searched a lot of topics regarding this and it is 10mm or 13mm but which one? I am going to but breather filter for that and it would be shame if I buy the 13mm one and it does not fit.

I would appreciate if someone could provide this measurement while they are working with their bike!

[SK Racing]

It measures 11.5mm, so a 12.7mm (1/2") filter should be fine.  That reminds me that I need to get one also.

[nurms]

Thanks dude!