Pontoon Boat & Deck Boat Forum

I am thinking of changing my 1999 Mercury 115 out for a 1986 Mercury 135 hp on my 24' pontoon with 3rd toon added. My top speed with the 115 is 22mph. I don't have a tachometer yet so I don't know if I could get more out of the 115 with a prop change. My 115 needs a new lower unit so I am thinking of getting a bigger engine to get more out of the 3rd toon but not sure if 135 hp would be a noticeable difference. What do you think?

depends on when Mercury switched to prop rated HP, that wasn't mandatory until 87-88' a 135 crank rated would be around 120hp prop rated. A triple tube, even without strakes, should be able to push 27-28mph propped properly unless its a really long and heavy pontoon. Under-skinning is highly recommended also and would make more a difference than an extra 20hp.

Thank you

The engine I was looking at turned out to be no good so now looking at a 2000 Suzuki DT140. Anyone running this engine on their toon? I am also planning to underskin at the same time that I swap engines.

If I go with the Suzuki I assume I will have to change my controls or will the Quicksilver controls work?

If I were you, I'd

1) install a tach
2) play around with props (and maybe even motor height) until I was hitting the max RPM's for my motor with two people on board and an average load
3) record my max speed several times with GPS
4) underskin and repeat GPS measurements
5) then and only then, decide if I wanted to invest in a new motor

I've heard great things about Suzuki's. Only drawback I am aware of is fewer shops repair them.

Good luck.

I failed to mention that the main reason I'm looking at motors is my 115 has a bad vibration at slowest speed. I assume it needs new lower unit which can cost as much as a complete motor. I would prefer to stick with Mercury but the Suzuki seems like a really good deal for the age and horsepower.

You can't go wrong with that Suzuki. Those motors are bullet proof.

That's great to hear because I went ahead and got it.