Fuel Mixture for 40hp Johnson

[j_Rilett]

Hey I bought a 14' starcraft with a 40 Johnson on it last fall (after it was too late to take out on the water). I'm getting it ready for the water, I just dont know what the fuel mixture should be. I'm hearing 50:1, but would like to confirm this...

 

[Joe Reeves]

Re: Fuel Mixture for 40hp Johnson

Regardless of the year of that 40hp (you didn't say), the mixture is indeed 50/1 .

 

[1946Zephyr]

Re: Fuel Mixture for 40hp Johnson

Most guys here will say, 24:1 on motors 1964 and earlier and 50:1 on the later ones. However, I don't see any design differences in any of the models, with the exception of the crank size and heads on the 1960 - 61's. The two early models had the compression releases on the heads. You might post a model number so we can narrow down what year motor you have.

 

[JB]

Re: Fuel Mixture for 40hp Johnson

The cutoff that OMC published in 1964 was 1964; all earlier than that get 24:1, all '64 and later get 50:1. OMC and BRP have both second guessed that a few times, but mostly to change some earlier models to 20:1 and 16:1.

Joe, however , is correct that the 40s (RD series) even as early as 1960 were equipped with all "frictionless" bearings and can probably run 50:1 with no risk. I trust Joe.

I am more inclined not to outguess the maker and would use 24:1 in Models RD-22 to RD-25, 50:1 in RD-26 and later.

All 2 stroke outboards of any age must use TC-W3 rated oils.