Compression test results: Good or bad?

[merc20076]

I did a compression test on my old Evinrude Lark VIII '68. Here are the results:

Top cylinder: 107

Bottom: 100

I wonder if my outboard is still in decent shape for this age? I will start it up in a big barrel very soon. It is still a little cool here to go boating.

 

[rolmops]

Re: Compression test results: Good or bad?

Those numbers are well within the 10% difference limit.It is all good.
Do a decarb and they might end up to be even closer together.

 

[kenmyfam]

Re: Compression test results: Good or bad?

Compression appears O.K. have you checked for spark yet ???
You should give the cooling system a service before firing it up though.
My 2 cents

 

[merc20076]

Re: Compression test results: Good or bad?

I've changed the water impeller recently and I want to see if it's OK, that's why I want to start it up. I can take the propeller off while running it in a big barrel.
.
I will put new spark plugs (NGK B6S???) right after the first ride. I shot some winterizing product last fall.

 

[bktheking]

Re: Compression test results: Good or bad?

Champion plugs bro! Leave the prop on , why would you remove it? To run it in gear with throttle? Don't - the lake is where you do it.

 

[CougarBait]

Re: Compression test results: Good or bad?

I dont know what the factory specs were and i have yet to find them online, but my '66 Lark VIII was 108/108 and from what i can tell this motor is strong and was pampered by the marine mechanic octogenarian that owned it previously.

 

[rolmops]

Re: Compression test results: Good or bad?

I've changed the water impeller recently and I want to see if it's OK, that's why I want to start it up. I can take the propeller off while running it in a big barrel.
.
I will put new spark plugs (NGK B6S???) right after the first ride. I shot some winterizing product last fall.

Do not try to run it without a prop in a barrel.It is a good way to get a run away engine and then you can sell the engine for parts.Your spark plugs are Champion J4C. The Evinrude engines were build with that specific plug in mind

 

[kenmyfam]

Re: Compression test results: Good or bad?

Agree with the above "keep the prop on" posts.

 

[JB]

Re: Compression test results: Good or bad?

This is another old, dead thread resurrected by CougarBait who won't read or obey our rules.