Compression For Johnson V4 100hp

[pmoet]

What should the optimal compression be on a 1985 johnson V4 100hp? (recently rebuilt).

 

[Dennisanoka]

Re: Compression For Johnson V4 100hp

You have to check all 4 cylinders. They should all be within 10% of each other. Low 90's is not bad, could be up to around 125. But hopefully they are all close to each other. Someone else may have better details but go measure them then re-post your findings. You'll get good feedback.

 

[hoeser]

Re: Compression For Johnson V4 100hp

I just rebuilt an Evinrude V4 140hp and my compression numbers are about 120-122psi on all 4.

 

[Chris1956]

Re: Compression For Johnson V4 100hp

pmoet, The classic answer is that all should be over 90 PSI and within 10% of each other. Also, who is to say that your gauge is accurate? If it reads all close in compression, the motor can ge tuned to run properly.

 

[pmoet]

Re: Compression For Johnson V4 100hp

thanks to all.. i will do just that