25 hp mercury looking for performance tips

[andrew81]

i have a 2000 25hp mercury, i'm looking for some tips to get a few more ponys . i've already opened reeds, drilled exhaust. i run a flat bottom 15ft plywood boat that weighs about 100lbs. dont get me wrong i'm already running around 40mph with this thing, but i'm racing with the 20hp johnsons(older style). they seem to be able to do alot more modifying. i know theyve got alot more cubes than me . but i'm running very close to them. and a couple more hp would put me by them. the johnson boys are giving me a hard time about the mercurys, and i'de like nothing better than to rub it in there faces when i get by them? any tips?

strong merc fan

[Tim Weber]

Raise the motor on the transom. Most Jon boats have a 15" transom. You can add a whole 1" under it easy. I did this on my fishing rig and I have the same motor.

Make sure its parallel to the bottom of the boat. You may want to slightly kick the motor out. You have to be careful or you will porpise.

Tim

[Sonny]

a sleeper?

Get a piece of aluminum plate and make an adapter plate for your tower housing and bolt a racing gearfoot on it....run the motor high enough on the transom that the center of the prop shaft is flush or maybe a half inch under the bottom of the boat...lol... that should wake her up...lol...leave the powerhead alone, you'll just ruin it if you start goof'n with it.

[David_L6]

i have a 2000 25hp mercury, i'm looking for some tips to get a few more ponys . ......i'm racing with the 20hp johnsons(older style). they seem to be able to do alot more modifying. i know theyve got alot more cubes than me .
strong merc fan

I believe that a 2000 model 25 horse Merc is a 24 cubic inch loop charged motor. "Older style" 20 horse Johnson? How old? When I think of an old 20 horse Johnson/Evinrude I think of the 22 cubic inch cross flow motors. Your Merc should spank 'em as is.

Mill the head a bit to up your compression. Other than that props and set up is where you should be looking.

[andrew81]

mill the head? do you mean planing? because these motors dont have "heads" they are a split block engine. the 20 johnson i'm running against is about mid to late 80s style i'me not sure what they have for cubes but i know they run the same 'big block' as the 30hp, and with a simple carb change there running 30hp. my motor is quite lazy out of the hole i'm not sure if its the modifying i did or just needs tuning. it seems to have a bit of a bog down low, but once the boat plains there seems to be lots of power there. i think if i could keep up with the boys out of the hole i'd go by them. they usually get me the first 50 feet. some times i get dicouraged and feel like getting a 55hp. but i cant do that till i concour the 20, 25 class.

strong merc fan

[David_L6]

mill the head? do you mean planing? because these motors dont have "heads" they are a split block engine. the 20 johnson i'm running against is about mid to late 80s style i'me not sure what they have for cubes but i know they run the same 'big block' as the 30hp, and with a simple carb change there running 30hp. my motor is quite lazy out of the hole i'm not sure if its the modifying i did or just needs tuning. it seems to have a bit of a bog down low, but once the boat plains there seems to be lots of power there. i think if i could keep up with the boys out of the hole i'd go by them. they usually get me the first 50 feet. some times i get dicouraged and feel like getting a 55hp. but i cant do that till i concour the 20, 25 class.

strong merc fan

OK, now I understand which motor you have and see what you're up against. I doubt that anything short of nitrous is going to give you the power boost you need.