I was going to ask if you were in a salt air climate, but you are in Westlake CA so it is somewhat dry there. If you are cruising PCH all of the time, you could have developed corrosion under the paint. If you do not know the history of the 2005 bike, it may be that the previous owner did some paint touch up on the heads, and the paint he used was not heat resistant. I am in Camarillo, and ride PCH every day, and none of my MVs have that issue.
Yeah, I can't imagine it's something like that either. It seems to me that it's some sort of electrical corrosion or somehow that cylinder is heating up more than normal through convection or something. That being said, I never expected the paint to blister like that if that's the issue.
It might be time to get a used 910r engine and do a heart transplant. ;-)
I have a 2005 Brutale S that I bought second hand a few months ago and its got quite a alot a places on the engine where the paint has peeled or flaked off . Just litte bits where the paint has blistered and come off. I didn't notice it until I detailed it , and now I see it all the time . Engine has no rust , it looks like its aluminium . I live in Sydney Oz but the bike came from Ireland in 2009 , I was thinking that maybe because it gets cold there it was a hot/cold issue . The bike had only done 9500 km but lots of that could have been track days , who knows . It doesn't look the best and it's got me thinking about pulling the engine out and painting when I have the money or the know how . In all other respects the bikes great , 113 rwhp with Arrow full 4 to 1 and PCIII .
Looks like some caustic cleaner was used, all the blistering is on the downhill sides of surfaces.
Either that or the metal wasn't cleaned well before painting....do the blisters pop and flake off? or are they hard, in which case it may just be a rough casting.