1967 Johnson 3 hp "fold-up" (Trouble starting)

datsunsrule

Cadet
Joined
Jun 19, 2010
Messages
25
Hi,

I recently acquired a 1967 3hp Johnson folding outboard. It's in excellent cosmetic condition, however when I tested the motor I noticed the pistons were seized. Upon inspection of the cylinders I noticed spotty rust on the cylinder walls. I replaced the piston rings, the head gasket, and honed the cylinder walls. I also added new points and thoroughly cleaned the carb. When I checked the compression, I was disappointed to find that it was only about 50-60 psi. I attempted to start the motor with no luck. My question is, is 50-60 psi an acceptable compression for a motor with new rings and head gasket?

Also when I was examining the coils I noticed that one of the coil wires was loose and could be removed from the coil with ease. I replaced the wire and used silicone to seal it. My experience would say that spark is most likely the issue, but when I tested it on the side of the motor, the plug threw a decent looking spark (about 1/2 an inch and blue).

And the funny part is, I have a spare power head, but because the motor is "folding", the adaptor plate and the power head are a little different.

I'm an OK mechanic, but I can't seem to figure this one out.

fuel+compression+spark= a running motor :confused::confused::confused:

Thanks!

Chase
 

Bob_VT

Moderator & Unofficial iBoats Historian
Staff member
Joined
May 19, 2001
Messages
26,043
Re: 1967 Johnson 3 hp "fold-up" (Trouble starting)

How are the points and condenser? They are VERY picky about having clean points. 50-60 is low but I have seen them run fine at 75 psi........... maybe it's time to move up a piston in size.
 

datsunsrule

Cadet
Joined
Jun 19, 2010
Messages
25
Re: 1967 Johnson 3 hp "fold-up" (Trouble starting)

Thanks for the info! Based on what you said about the points/condensor, I think my next move might be swapping the entire ignition system from a spare 68' JW conventional shaft, for trouble shooting purposes. But in regards to compression, do you know if there's is a break-in period for new rings, or should it be 75+ immediatly following an overhaul?

Chase
 
Top