1999 mercury 125 outboard 2+2 2 stroke

[claytonalbright]

I am relatively new to boating and trying to get some info on my boat I just bought. I am a mechanic by trade but no nothing about boats.

I just bought a 99 18? Sea ray with a 99 Mercury 125 2 stroke. The motor runs great as far as not missing a beat or anything. But it tops out at about 38 mph at around 3900 rpm. I have asked around and everyone seems to think that is low but have no idea what the issue may be.

Since I got the boat I replaced the plugs, wires, fuel filter, and cleaned the carbs which has had little effect on how the boat operates. I believe it has a 18 pitch prop.

Any info anyone has on this would be great, I just don?t want it to be running lean and damage the motor or anything.

 

[Blown Challenger]

Re: 1999 mercury 125 outboard 2+2 2 stroke

Welcome,I am also semi new to boating.I have read here that the prop size has alot to do with engine and boat speed.Hopefully some of the crusty sea hags will chime in. lol

 

[claytonalbright]

Re: 1999 mercury 125 outboard 2+2 2 stroke

I have heard the same thing but i would think that the motor would still turn the 5200 rpm's just would not have the speed. But i am not sure. I don't want to take it to the shop.

 

[1stout]

Re: 1999 mercury 125 outboard 2+2 2 stroke

sounds like the diameter of the prop is too much for the hull, it should be running around 5200 at WOT as you stated. The best thing to do when new to propping is to find a prop shop that will allow you try different props until you find the right one. You pay a little more but at least you aren't stuck with a prop that doesn't work with your boat. There is a lot to choosing a prop, google search it, I don't feel like typing a novel here.

 

[Blown Challenger]

Re: 1999 mercury 125 outboard 2+2 2 stroke

I guess its good the guy I bought my boat from gave me 5 ss props.But none on the motor so now I get to go and spend the day prop testing.lol

 

[leach0369]

Re: 1999 mercury 125 outboard 2+2 2 stroke

I also have a 18ft Sea Ray but I have a 135 2 stroke. At WOT I only go 5300 RPM' s and around 43mph depending on the trim level I have it at.. I have a SS prop and it is a 17 degree..

I guess its good the guy I bought my boat from gave me 5 ss props.But none on the motor so now I get to go and spend the day prop testing.lol