Posted by Rick Denney on March 26, 2001 at 16:28:48:
In Reply to: Re: Deposits on valves and valve casings posted by Joe S. on March 25, 2001 at 20:41:48:
Yup, this happened with the Monel valves on my Yamaha. A couple times that first year, I buffed the valves carefully with white polishing compound, a very light touch, and absolutely making sure that the buffing wheel wasn't digging into the edge of a port. After that first year or so, the problem went away. At first, I used Al Cass, but later switched to Alisyn. I figure the polishing removed less material than lapping, but that's a guess. I haven't really had the problem since then.
As to what is actually happening, I'm no expert on galvanic corrosion, so I can neither confirm nor deny Joe's hypothesis. It passes the plausibility test, but that's about all I can say.
Rick "who ain't no chemist" Denney