On Fri, 28 Nov 2008 08:30:06 -0500, Dana M. Hague
wrote:

On Thu, 27 Nov 2008 09:37:54 -0500, "Peter Dohm"
wrote:

IIRC, snowmobiles are/were derived from chain saws--which required an engine
light enough for a man to carry and use as a hand held tool. That made them
an obvious choice for another application were light weight was the most
critical factor--even at the cost of reliability and maintenance
intervals...

I've never heard that, seems unlikely... they are really very
different, except for both (along with outboard motors) being
2-strokes. All for the same reason of light weight.

-Dana
Some of the first ultralights DID run chainsaw motors - just like the
go-cart crowd. Some of the small aircooled outboard engines were also
used - and some early snowmobiles also used a converted aircooled
outboard. (horizontal twin Johnson Snow Cruiser and OMC)