Merc 115 "sweet spot"

[izzybird]

Was considering putting an '84 merc 115 on my pontoon boat, as the motor was free. Reading some posts on here I'm coming to the conclusion that these motors don't like to "putt around". I don't plan on running this thing more than about half throttle, think it will ruin it? Just rebuilt it, don't want to do it again.

 

[Yepblaze]

Re: Merc 115 "sweet spot"

Just prop it accordingly, and it should be OK.

Accordingly for you application may take it well into it's max RPM at WOT.

Also you may want to consider minimal cup in the propeller design to allow some considerable slip.

 

[jimmbo]

Re: Merc 115 "sweet spot"

Prop it to run between 5500 and 6000 rpm and it should be ok. These motors run best above 3000-3500 rpm. They run ok below that , they just run real good above that. They idle very smooth;y too. Just use fresh gas and a good TC-W3 oil @ 50:1 and it will live a long life.