Max rpm merc 50 4 stroke

[nubote]

Can someone tell me the max rpm for my "new to me" 2006 merc 50 hp 4 stroke motor on a Princecraft pro165sc.

I have ordered a manual for it, but I tried out the boat and motor yesterday, and found the rpm could go well above 6000. The previous owner told me that the boat had trouble getting on plane when he got it, and the dealer put a new prop on it. I'll have to get the numbers off the prop next to see what pitch the prop is.

[cyber16]

I have the 2004 efi 4st and if you look on the stamp tag on the motor yours should say 6000 rpm, i run mine around 5750-5850 as that is where it hits its rated HP, simply backed off the throttle a tad
I use a 13p prop on a Alumacraft competitor 170, this prop will get me right at 5950/6000 wot

[jrdonicht]

Motor Specs
Manufacturer: Mercury
Model: "EFI"
Year: 2006
Horsepower: 50.0
Cylinders: 4
Type: 4 stroke
Gear Ratio: 1.83:1
Min WOT RPM: 5500
Max WOT RPM: 6000
Spline Count: 13
Drive Type: Outboard

[nubote]

OK, thanks guys. I found the stamp on the motor mount now. 6000.

So does "Min WOT RPM: 5500" mean if it makes less than 5500 your prop pitch is too high, and "Max WOT RPM: 6000" means prop pitch too low? Or, if it's above 6000 or below 5500 at WOT, you have the wrong prop?

[jrdonicht]

You are correct on all. cyber 16 is running in the ideal range

[yarcraft91]

I have the same year and model motor. I found a 13 pitch Black Max (3-blade) or Spitfire (4-blade) aluminum prop was ideal for my 16.5' Alumacraft Lunker SC. Mine is a 76" beam boat.

[bob888]

Are you sure your tach is accurate?

In 2008 had a new 60 hp merc four stroke installed. Before prop testing I had the mechanic hook up their computer to my motor to determine how accurate my tach was. When my tach read 6400 rpm the motor was acually running at 6000 rpm.

My Merc 60 hp four stroke has a max recommended RPM of 6000. At 6200 it is supposed to beep and at 6400 shut down. I've run at 6400 RPM and never got a beep, let alone a shut down.