Um, so what's the "yes" part?
When I've washed the bike and run it afterwards, the excess water seems to spin out of the holes in the clutch cover pretty quickly. I do have stainless springs and screws and a red anodized cover, but a stock basket and plates. How about the bearing for the pushrod? Is that prone to water damage?
Did a search on this and figured I'd resurrect this old thread vs. start a new one.
Yes is "I have ridden in the rain with an open cover"
No is "there is no negative affect in performance or wear"
In addition to my FHE (limited to two years of open cover) I have confirmed with mechanics including BCM. No Duc shop or wrench has expressed even the slightest reservation (beyond the cosmetic matter of rusting springs).
Funny, I just talked to my mechanic about this subject just before we got rain in LA.
We were looking at an old beat-up M900 with a vented clutch cover. The pressure plate was just awfully dirty and I think it was stock. He basically said there is nothing to worry about. Rain, snow and even some sand getting into your vented clutch won't effect the engine in any major way. I hear the bikes in the Paris-Dakar Rally have vented clutch covers.