1958 Johnson seahorse 35 lacking power

[1958woodboat]

Motor will rev in neutral and in water barrel, but when in the water, it only revs up to maybe 1/2 throttle and only goes 10mph. Sorry I’m new to the forum and these old engines and just need some help

 

[racerone]

Sounds like it is running on 1 cylinder.----Or you need to adjust the lower carburetor mixture needle.----The book setting is to get the motor started and keep running.----You MUST fine tune once the boat is underway.

 

[1958woodboat]

I’m going to guess one cylinder, I attempted to adjust high and low speed needles with no avail

 

[oldboat1]

I don't remember from your earlier thread whether you measured spark? Do that at the dock or in the driveway -- might find and correct problem with that step. Dropping a cylinder (i.e., losing spark) is harder to detect, but could be a next step. Did you replace old coils?

 

[1958woodboat]

I did not, it ran good in the barrel so I assumed it was good.... bad decision when I got on the water haha. I need to replace the old coils boat hasn’t ran since 1993. Do you know where I can get some?

 

[oldboat1]

right here at iboats. Or NAPA? (get an open air adjustable tester too. $10 or $15.)

 

[1958woodboat]

Iboats doesn’t pull up any parts for my motor on here,1958 Johnson rd-21 E

 

[1958woodboat]

I believe I was looking in the wrong spot! I was looking under my model number parts schematic. I was able to find coils now. I ordered two of them and i am going to pick up an open air adjustable tester as well. I will keep you guys updated!

 

[lindy46]

Did you look at the coils? I believe there is an inspection port on top of the flywheel. remove it and check. If they're not cracked, they may be okay. You may just need to clean/adjust the points, which can be done through the inspection port. If it was running in 1993, the coils had probably already been replaced, as those original coils most likely wouldn't have lasted 35 years.

 

[1958woodboat]

I’ll take a long ok at the coils tonight, what are the adjustments for the points? Also what is the easiest way to get spark plug wires as mine seem to be pretty dried out

 

[racerone]

You need 7 mm WIRE core plug wire. ----You remove the magneto plate.-----Put wire through the plate from the bottom.-----Thread wire into the coil.----Now put coil in place at the proper position for air gap with magnets.

 

[1958woodboat]

What is proper air gap for magnets?

 

[racerone]

Most shops have a ring ( dummy flywheel ) to set the coils in the right place.----Best to look at some tutorials on the wonderfully simple magneto.-----Search for ----leroysramblings.-----Johnson outboard universal magneto.----And others as well.

 

[1958woodboat]

So I checked spark with tester and it is super strong ( no need to replace coils) so then I put in fresh plugs and went out, it idled and ran good, but above half throttle I had to pull out the choke to get it to run good.

 

[oldboat1]

Remove, disassemble and soak the carburetor. Clean every tiny opening you can find with soft wire, followed by carb cleaner.

 

[1958woodboat]

will do i will keep you all updated

 

[42 Clyde]

I have nearly the same motor with very similer problem. Please let us know what you find. Im pulling my hair out over mine.

 

[lindy46]

Get a carb kit and rebuild the carb.