Topic: gas oil ratio for a 1968 Johnson 15hp electric start

This topic has 14 replies, 7 voices, and was last updated 2 years, 11 months ago by Mumbles.

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May 4, 2021 at 2:10 pm #237694
Jim Potts
Participant
Hello,
I just purchased a 1968 Johnson 15hp electric start outboard motor. I have a couple of questions:
1. what is the oil to gas mixture ratio?
2. does anyone have the starting procedures for this electric start motor. I bought it without starting it because it was just a throw-in with the boat and trailer.

thank you!

Jim
May 4, 2021 at 2:35 pm #237695
crosbyman
Participant
Canada Member - 2 Years
50/1 usually in those years

before you start it

check or better yet replace the impeller …. change gearcase oil and check for water intrusion if you have water you will need to reseal the GC … use new nylon washers when closing it up

pump it up with fresh gas and try it out … check water pump operation you may need a carb job (not complicated) if rough

post mdl #…. I found no 1968 15hp Johnson listed

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- This reply was modified 2 years, 12 months ago by crosbyman.
May 4, 2021 at 3:08 pm #237701
Jim Potts
Participant
Thank you! I’ll check to make sure I have the year right.
May 4, 2021 at 3:25 pm #237703
crosbyman
Participant
Canada Member - 2 Years
see listing for 15hps

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May 4, 2021 at 6:16 pm #237717
Jim Potts
Participant
yes, you are correct. It’s a 1956 Johnson 15hp electric start. So it must be the E-10. Besides the helpful info you shared on what to do before trying to start the motor. What about the actual steps for starting it? Choking, throttle, push button, etc. All the outboard motors I’ve started in the past have been manual pulls.

thanks again.
May 4, 2021 at 6:19 pm #237718
Jim Potts
Participant
Apologies to everyone, the correct year of my motor is 1956.
May 4, 2021 at 6:26 pm #237719
Jim Potts
Participant
and with a 1956 year motor; still 50:1 gas to oil mix, right?
May 4, 2021 at 6:38 pm #237720
bobw
Participant
US Member
Nope. If it’s a 1956 model, correct mix is 16:1. Some will tell you that you can get by with 20:1 or 24:1 but I think it best to stay with original factory recommendations.

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."
- This reply was modified 2 years, 12 months ago by bobw.
May 4, 2021 at 8:04 pm #237724
crosbyman
Participant
Canada Member - 2 Years
if you have a pressure tank system … keep the lid shut so pressure can build up in the tank to feed fuel up to the engine…

fill the carb by pumping the tank button 5-10 times

typical you have a electric choke push button for the electric choke so just push it while starting the engine release it when started throttle in neutral always

btw great engines…pamper it oil it as per specs !!

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May 5, 2021 at 1:28 am #237733
JOHN HOLBIK
Participant
Johnson made a 15hp around 1968 it was called a Percheron I know this for a fact as one of our customers at our resort brought one and I guided him for the week.The motor ran well and trolled great I believe it was a one year offering I also saw it in an advertising brochour back in the day.It had a hood on it that looked just like the Gale 15 from the early 60s.Maybe it was only avalible in Canada they called it a work horse model.
We ran all our outboards from 1952 to 1964 on 25 to one and the later ones on 50 to one all of our motors had thousands of hours on them I have a 56 Johnson 15 hp it is my favorite engine it has a gazzlion hours on it and it runs perfect..
Our mix system was simple one 5 gallon milemaster tank one quart oil for old motors.
1 5 gallon milemaster tank for newer 1 pint oil we never went with the later omc 100 to one.
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