Fuel Efficency

[kevinwd1]

I recently got a 28hp 1962 Johnson 2 stroke outboard going .I took it for a for a long run to check reliability and fuel consumption .The result was the motor keep going for two hours with no problems and used about 6.6 gallons (25 liters) and did approximately 46miles (75klm).I don't think that’s to bad but was wondering when 2 stroke outboards started getting more fuel efficient. I'm thinking of looking around for a cheap motor to fix up(might have caught the bug) . May look at newer models if they are a lot more fuel efficient but I do like the simple nature of the old magneto ignition.

 

[steelespike]

Re: Fuel Efficency

A 1962 catalog indicates 1 3/4 to 2 hours per 6 gallon tank.
2 1/4 - 2 1/2 at reduced throttle. max speed about 30.
Rule of thumb wot fuel use is about 10% of the rated hp.
or in your case about 2.8 gallons per hour.3.3 per hour seems really good. Motors in that era are indeed a little higher.
That 2.8 gph is regardless of if its pushing a houseboat or a light t runabout.
You may be able to closer to the 3 gph by being sure the motor is in excellent tune.
MPG will come from being sure the boat/motor combination produces the most speed for a given throttle setting.
Newer motors do a little better. When we went to a new 77 Merc 50 from our 62 Gale 25 the 50 did noticeably better
when driven in the 25s speed range.Overall fuel use was noticeably better because the 50 could get to our destinations quicker
especially with a load at partial throttle.