1964 Johnson 100 HP Compression

[RideRMK]

I just bought a 24' houseboat that has a 1964 Johnson 100 HP outboard on it. I paid a marine mechanic to check out the motor for me, and he said it's got a lot of years left on it, but his invoice says the compression was at 70 psi on all cylinders. Doesn't that seem low?? Also anyone have the real scoop on the reliability and longevity of this motor???

 

[12Footer]

Re: 1964 Johnson 100 HP Compression

70PSI is not that bad for a new1964 outboard. They had lower compression from the factory.<br />But the real "telltale" is the fact that the compression readings were THE SAME on all cylinders. If it only had 50PSI and all equal,I wouldn't worry about it.<br />They were great motors! They were very reliable, could handle salt water exposure better than all the rest.<br />They were thirstier than most as I recall.<br />Been many moons.