1993 Johnson 40 J40EETB

[boben2830]

I am wanting to make this motor a 50 hp.I have done so far, 50 carbs with 49D hs jets, upper carb #31 ls jet, lower carb # 29 ls jet, 50 reed stops, CCMS fiberglass reeds. I have seen no performance gains after these mods. Plugs are QL78YC I looked on CDI website and they recommend QL77JC4 plugs. I spoke to OMC ( BRP ) about the 50 head ( p/n's ) are different. I ordered a 50 head and found no differences in any diminsions. This motor has low hours and sat up for years. The seller ( Freshwater Outboards ) rebuilt top end ( 0.020 ) over, new rods, pistons, bearings & seals. New water pump and gearcase seals. Am I missing something here? Any help would be greatly appreciated, Bobby..

 

[steelespike]

Thats a 25% increase.I'm taking a guess there are some fairly serious port work perhaps both size and timing.
Have you compared exhaust system parts?
Did you do any research to see what it would cost to simply trade up?
What was the wot rpm and gps speed before?Prop size, wide open throttle rpm and speed now?
Have you checked timing advance?

 

[steelespike]

Did a little research Present day 40 and 50 hp Evinrude Etec kind of apples and oranges but interesting. Fastest 40 was 32.6 w a13 7/8 X 17 @ 5425 slowest was 26.2 with a13 7/8 X 13" at 5700.
fastest 50 was 34.9 w 137/8 X 19 all similar aluminum boats all SS props. slowest was 30.7 w 13 1/4 X 15" at 5775. These are a different ratio 2.6 something
I think yours is 2.42. Roughly speaking your "50" would make about 36 with a 19" prop at 5500 rpm.

 

[gm280]

I don't know for certain, but I would think that doing all that and buying the different parts as such, that you would have come out cheaper by buying a 50 and even then the engine would probably last longer and probably get better gas mileage as well. Don't know that for certain, but I would assume so... JMHO!