Thank you to all who responded.
I like the 5/40 because I think it will circulate faster than a 10 or 15 weight at start up, which is where most wear occurs, at least that's what I've heard.
The Valk is a wonderful bike, it does everything well, easy to handle at slow speeds, comfortable, good power and has been extremely dependable - plus, I love 6 cyl bikes.
The specs on the Delo and the Rotella, both 5/40 are virtually identical and I've had no clutch problems (that I am aware of) with the Rotella that I've used. In fact the Delo 5/40 syn has less moly than the Rotella - so I don't see how it would cause a slipping issue.
My Valk (2001) just calls for an SG rated oil, says nothing about JASO ratings.
Why did I buy the Delo? Well, I know Shell is a Royal Dutch company, and Delo (Chevron) is an American Company -- I try to support American made products whenever possible.
I am not an expert on what a clutch would feel like if it slipped, would it be obvious?
RevRider