As you might have read in another posting of mine, 4-strokes give better fuel economy
than 2-strokes because the low speed jet on a 4-stroke is very small and only allows
the minimal required fuel through it. The down side, as I mentioned before, is that
this tiny jet is more subject to clogging. This latter problem can be overcome by
proper maintenance, which includes not leaving gas sit for long periods in the carburator.
Certainly all the newer gasolines with additives don't help. Yamaha recommends not
using gasohol, but it's almost impossible to avoid it.

Sherwin D.


wrote:

Another thread concerning a 9.9 hp got me wondering what to use to
power a boat I will build. It needs to be up to 75 hp.

Does a 4 stroke really give noticeable increase in mpg?
Are 4 strokes really finicky compared to 2 strokes (I mean reliability).