1970 johnson 4 hp compression ?

[morenc00]

I got this outboard with an other outboard I bought, it looks pretty rough from the outside, the compression is around 90 psi is it within acceptable range ?

 

[oldcatamount]

Re: 1970 johnson 4 hp compression ?

I have a '69 Johnson 4hp and the compression is 80lbs on each cylinder and it runs great! they are tough little motors.

 

[JB]

Re: 1970 johnson 4 hp compression ?

On a small rope start outboard anything over about 60psi is acceptable as long as the cylinders are close. . .like within 10%. . .to each other.

 

[1946Zephyr]

Re: 1970 johnson 4 hp compression ?

90 psi on a 4hp thats 41 years old is excellent. That motor should have lots of life in it. Point gap is .020, plugs are .030 and mix should be 24:1

 

[boobie]

Re: 1970 johnson 4 hp compression ?

X 2........

 

[morenc00]

Re: 1970 johnson 4 hp compression ?

Thanks for the info, I will work on it and try to get it run right now it make a weak spark, the coils have lost most of their insulation. I will put new ones with a carb kit and impeller.

 

[boobie]

Re: 1970 johnson 4 hp compression ?

When you get done with your ignition repairs the spark should jump a 1/4" open air gap.