Re: Mercury 1999 25 hp 2 stroke power head
Pretty much any 25, 2-stroke from 1985-now. All the bolts patterns are the same, everything. The only difference in the year models is in the 90's they began using "mercosil" cylinders, and the older ones had chrome lined bores. Everything else is the same though. I would get a 90's model powerhead, that way if something did happen and you had to have it rebuilt, you can have the cylinders bored. If your looking at the back of the motor, look on the right side of the #1 cylinder and you will see "mercosil" stamped on the block, thats the one you want.