The wee black cap on the final drive breather... is it removable? I ask before I try and butcher it. My reason for asking is that after some rather spirited riding round central Wales last week it threw EP90 all over itself (no, it wasn't over filled ). I did a full oil service this weekend and found the final drive full of milk (!); based on the number of puddles around here water ingress was probably the cause of the EP90 egress. What I propose to do is what I used to do with my V50s: remove the cap and add a length of breather pipe sufficient to retain any EP90 fling and tucked away to prevent any water ingress.

Wasn't a few wet pants moments?

I've got completely waterproof waterproofs, I'll have you know! Actually, if I hit a big puddle hard enough (40mph+) the resulting spray hits the bottom of the fairing, migrates up the inside of my waterproofs, runs down my boot and blinds me all at the same time. I love this country.

Dai, in the not so distant past I was surprised during a final drive fluid change to discover water contamination.  It was quite a puzzle, since I live and ride in an arid environment. The water must have come from a bike washing, yet I never use high pressure and take care to avoid hosing down the final drive area.  In response to my post, someone (Inge, I believe) offered some suggested mods to the vent, which I did.  I've yet to change the final drive lube since I made the mod to the vent.  I'm hoping that when I do I'll find nothing but lube drains out.  If that proves not to be the case, I'll sure be interested in your experience with an extended vent tube.
I'm terrible at searching, but you may find the relevant posts here somewhere.

Condensation, is my guess. Although you live in an arid environment the bevel drive will have it's own microclimate inside. Given that ID is a ways inland, I hazard a guess that there's quite a temperature swing over twenty-four hours. Could also be part of my problem, of course.

[Edit] This post? https://www.k100-forum.com/t8979-k100rs-final-drive-mystery

Yes, that's the one.

Dai, in answer to your question, the black breather cap is 'just' a push fit and it should come off with a bit of leverage.

Paul.

Thanks Paul. I love how every single topic gets sidetracked...

When I changed my splines I left the final drive unit on its side for a few days and oil got into the space just below the vent.  Later air expansion blew this out of the breather as the compartment does not drain down into the main part.  I thought I had a fault but there was none.
Once that little compartment (below breather) is empty oil not longer comes out. ☺