johnson compression question

alanR1

Petty Officer 2nd Class
Joined
Apr 13, 2003
Messages
109
i have a 1983 90hp johnson that I am re-building and have gotten some help from you guys and i have another question for you. I am just about to bring her back to life and want to know what my compression should be on the cylinders.
 

mistygale

Recruit
Joined
Jul 8, 2003
Messages
2
Re: johnson compression question

after your rebuild your compresion should be around 100 to 120 psi make sure you do your compression test with your throttle open, your engine wonèt start if your below 90 psi and make sure you donèt have to much oil in the cylinders it will give you an incorect reading
 

Solittle

Fleet Admiral
Joined
Apr 28, 2002
Messages
7,518
Re: johnson compression question

I wouldn't make much of whatever the readings are (so long as they are within 5% of each other) until the motor is broken in. You need to do the break in just as if it were new.
 
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