4 stroke engine for hydroplane?
 

I've always been a sailboat/kayak kind of guy but am thinking of
building a small hydro with my 12 year old. I know little about
outboards but was wondering if I could use a 4 stroke on this boat (9.9
horse on 8 foot Minimax). I would buy used and can live with the price
difference. The 6 horse evinrude kicker (early 80's vintage?) I have on
my 20 foot sailboat is easy and cheap but you dont have to be a rocket
scientist to see it puts out the emissions. So the question is, besides
cost and weight (20 pounds?), what do I loose if I were to use a 4
stroke on this little racer? Also,any good books out there that I could
use to educate myself about these motors?
Jeff