In the service manual pertaining to evaporative loss systems, it states that the cap will allow air in.
One way vented, I guess.
What I don't know if if this is true for Ca. models only.
I know this probably just adds to the confusion on this issue,
but thought it worth mentioning.
I noticed that last night while pondering what to do with
the ELS on a bike that lives in Mo.

Said Molly to James, that's a fine motorbike. Richard Thompson