Quote Originally Posted by Droll-l6 View Post
Found some pictures .

First a power ported piston, then a non PP cylinder (Merc 1400, 1972), last picture shows a PP cylinder .
Mercury used power ports on the 1973 > 1977 Merc 1500 ( + 1500XS up to 1978 ), 1978 > 1981 Merc 1400 ( basically the same as the 1500 ), 1982 >1988 115hp ( prop shaft rated, only minor differences from the 140/150hp models ) .

Arne Kjetil
these are just like some of my 700x/650xs internals,but pistons have 2/3 rings.....why ..less drag???????????better seal????