50:1
Need to know if its 2 or 4 cycle.
The dry weight of a 1983 model, 40hp Mercury outboard, is 156lbs.
The dry weight of the Mercury outboard FourStroke 40 HP boat motor released in 2005 is approximately 250 pounds. Later versions of this motor are slightly lighter.
0d161839
The 1997 model, 40 hp Yamaha, requires a 50:1 ratio. This is roughly one pint of 2 cycle oil to six gallons of fuel.
50 to 1 according to my mechanic
An Oil Injected motor will have a separate Oil Resevoir, so mixing Oil and Gas is not required, and in fact inadvisable.
I would say one per spark plug.
The plug gap for a 1995 model, 40 hp Mercury is .035 in.
A 40 hp Mercury outboard, serial number 5897057, would have been manufactured in late 1981.
For the 1995 model 40 hp Evinrude, mix at a 50:1 ratio.
I have a 1996 Mercury 4 cylinder 40hp with 125 Psi across all 4 cylinders. I also have a mid 80s Mariner/ Yamaha 40hp 2 cylinder with 123 Psi both cylinders. I'm not sure what factory specs are, but maybe this would help.