I use Fuchs Silkolene V-twin 20-50 and have not noticed any undue valve train noise.
A fully synthetic oil alternative for an extra £10 per oil change is Motul 7100 4T 20W-50. It meets Harley Davidson V-Twin specifications. I have used this since the first oil change (almost 12,000 miles ago) and have had no excessive valve train noises either.
http://www.opieoils.co.uk/p-913-motul-71...with-ester.aspx
