Having spent some time messing with air cooled engines, I can say that
while they do offer advantages, they are no panacea. It's just hard to
remove enough heat using air alone, so they tend to run hot, and it's
even more difficult to provide even cooling, so some parts run a lot
hotter than others. The air cooled VW's and Porsche's are fun for sure,
and granted they are relatively simple to work on, but the catch is that
they *need* to be worked on frequently.
