Johnson 1949 HD 25 No Spark

[TiIngot]

About 30 years ago this 1949 was given to me by my neighbor.  I tried using it on my side mounted canoe but with me and the motor in the rear it was stern heavy.  The one time I had my neighbors 13-year-old son in the front it ran about 45 minutes up the Mahoning river and started really running poor.  We shut it off and paddled back down stream.  Thinking it was overheating I replaced the rubber water pump but never got it running again.  The starter rope broke, and it sat in the shed for over two decades.

Now I am trying to get it running and give it back to my neighbors now 43-year-old son.  It was stored with no fuel in the tank and the carb drained.  First, I repaired the recoil rope and found no spark at either plug.  Next the compression test only shows 52 psi in either cylinder.  Last what could cause loss of spark in both plugs?  It went from running to not running.  Thus, I have a lot of questions, and I will number them.    1.)  I have spent a week troubleshooting the no spark issue but before I go on this path, am I wasting my time with only 52 psi compression?    2.)  Can something be used to pour into the plug holes to soak the pistons that may release stuck rings thus increasing compression?

On to the no spark issue.   3.) When it was running a couple decades ago, was it possible it was running on only one cylinder?  I ask because I cannot figure out what common denominator that would kill both circuits except the stop switch.  I checked; the stop switch is not shorted to ground except when the magneto is in the stop position.   4.)  What is the correct MFD range for the condensers?  The following are diagnostic actions I have performed to date.

a.  Both Champion J8 plugs checked ok using an ohm meter continuity check.

b.  Substituted second plugs for test purposes.

c.  My spark plug test light is working properly.

d.  Coil shoe gaps on each magneto set at .012 all three shoes.

e.  Continuity of each primary and secondary coils on each magneto checked ok.

f.  Continuity of each spark plug wire checked ok.

g.  Both point sets removed, cleaned points filed clean and installed to .020 gap.

h.  Stop switch has no continuity to ground at any magneto setting except when it is in the stop position.

i.  Both condensers tested, one at 206 mfd, other at 246 mfd.  Are these readings ok?

 

I’m stumped by an outboard as old as I am.  I should know how plugs, points, condensers and magneto’s work at my age.  Maybe it is old age senior moments acting on he.

 

TiIngot (Titanium Ingot Melt Shop Manager)

 

 

[Sam M.]

Are the flywheel magnets still strong?

You could also try checking the gap on each spark plug.

Are you pulling it over with a rope or turning the flywheel by hand because it might not spark if being spun over too slow, which could be the case if you aren’t using a rope.

I wouldn’t worry about the compression for now.  Just don’t feed the motor any less oil than 16/1.

[Author]

Posts