Motorcycle Repair: Honda Goldwing oil frothing, honda goldwing, coolant loss

Question
My 1984 Goldwing, with 73,000 miles, suddenly started having intermittent lifter clatter that progressively got worse after the initial event.  The noise would start on the left side of the engine and then pass on to the right, then start the process all over again.  Then, it might clear up and not show up for another 100 miles.  
 On a recent ride it was quiet for about 80 miles and then suddenly reappeared.
 Finally, it got so noisy that it was apparrent that ALL the lifters were flat. (Yes, I have changed oil and filter and made sure the oil level is not overfilled.) It literally sounded like someone driving rivets!
 I ended up taking all the lifters out and bleeding them (they all had lots of air in them).  This totally fixed the problem...for about 200 miles, then it reappeared intermittently on the right side only.
 When I pulled the oil filter after one event, the oil was foamy.
 I suspect an air leak somewhere on the intake side of the oil pump...but how can this be?  Is there any part of it exposed to atmosphere?  Also, the question "why is it intermmitent" and "how does it self-heal" only to reappear?
 There is no oil loss from leakage or burning.  There is no coolant loss or any contamination of the oil. The oil pressure light never comes on, even when the engine is hot and idling.  The filter is always clean...no metal, etc. I change oil regularly and the motorcycle is ridden regularly and gently.
 I have always used 10W40 Castrol but recently changed to 20W50 Castrol without any noticeable improvement of the problem.
 Thank you for any help you might be able to give.

Answer
Hi Ronald,

Have you tried switching back to a lighter viscosity oil? Does the problems exist with lighter oils?

Flothing is normal with this engine. Air in the lifters is a result of excessive air in the oil.

I suggest trying different brands and viscosities of oils until you find a combination that works.

I return tech information files by email. There was no email address with your question as requested and explained in my instructions.

Respectfully,
Mark Shively