operating rpm for 2 stroke 90hp merc?

[nosfedgta]

I am new to outboards and Have some questions. Is there a recommended cruise rpm for a 2003 90hp 2 stroke merc? I know full throttle rpm is 5500 rpm or so. I was just curious if there is a rule of thumb when cruising long distances?

Drew

 

[robert graham]

Re: operating rpm for 2 stroke 90hp merc?

Mine is a Yamaha 90HP 2 stroke so should be similar. The best cruise RPM for fuel economy is 3500RPM, just up good on plane and running about 25MPH. Check this site for more info: Yamaha Outboard Performance Bulletins, plug in your boat/motor combination for info regarding MPH, MPG, GPH at various RPM's. A boat will run best efficiency while up on plane, not plowing through the water at slow speed, guess it makes sense, but I used to think that just going slow meant good miles per gallon.

 

[jasonbailey]

Re: operating rpm for 2 stroke 90hp merc?

It really depends on: prop pitch, how fast you want to go, and how much fuel you want to consume. I have the same motor, a little newer, on a 18' tri hull. I usually cruise in the 4,000-4,200 RPM area and fuel consumption is not too bad. On a calm day pulling tubers, doing a lot of hole shots, and running WOT it will gulp the fuel.

 

[nosfedgta]

Re: operating rpm for 2 stroke 90hp merc?

not to worried about the fuel consuption. Its very good on fuel compared to my old blackmax 175 lol... I just fish in a lot of tournaments and want to get to places quickly. I have been cruising about 5000rpms. Just wondring if that was too high for long periods of time.

Right now it has a 4 blade alum prop.. its 13diam and 21 pitch. I am a car guy so like I said im new to outboards and just dont want to hurt things. I know that in my car im not going to cruise anywhere at 5000rpms for long periods of time ...lol