97 Mercury 115hp offshore problems

Jhwaco

Cadet
Joined
Jul 13, 2019
Messages
18
I had major tune up couple years back on my mercury 115hp with 17 pitch 3 blade. . When they did a compression test they said one of the cylinders was a little low and they said they made the carb rich for that cylinder. The problem I’m having is max rpm on the engine is 5000 on the water WOT. It runs fine and very dependable but struggles on my 19 ft challenger with power takes awhile to plain out top speed is 35, another issue is trim on the boat it seems like it almost has to be trimmed down to get a speed ride or it bounces bad in the water. I thought about trying 15 pitch 4 blade. Any suggestions to get rpm or is rpm needed or try a 4 blade I really am against complete rebuild on it.
 
Last edited:

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
38,471
Do the compression test today.-----Or remove the exhaust cover to inspect pistons and rings.----About 25 bolts to take out.
 

flyingscott

Fleet Admiral
Joined
Apr 8, 2014
Messages
8,152
Your motor has an rpm range of 4750-5250. How did they make the mix richer only the top 2 carbs are adjustable. Have you tried moving weight to the front of the boat.
 
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