converting a 1993 25hp - 20hp

[merc61]

Hi all very new here looks like a great site!
I am in need of some info on converting a 1993 25hp outboard motor down to a 20hp, We race outboards here and have found a nice 25hp mercury(1993) and the limit is 20 hp.
Any and all help would be greatly appreciated

[boats.net]

No not sure never tried it.

[merc61]

Quite sure people have done the conversion the other way.making a 25 out of a 20, just need to know what is involved carb , restricter plate etc.

[merc61]

seriously no one on a mercury forum knows the difference between a 20 and 25hp early 90's mercury outboard?

[pfysch]

Converting 25 to 20

Check the carburetor parts list at Mercury. Take note of the main jet sizes. For example the 18 hp jet smaller than the 25. Change jet? Find a model year That Mercury made a 20 hp and a 25.
Perhaps other modifications are required.
Good luck

[Ski]

You might want to keep in mind that carb jetting is in relation to the air flow and just throwing smaller jets in it will just make it run lean. If your racing I'd just throw on some 20 Hp decals on the cowl and start winning.