Help analyzing my compression test (1971 6hp Evinrude Fisherman)

[markymarc1]

This 71 Evinrude 6hp Fisherman is new to me.

After putting new plugs and gear oil in, I pulled twenty times, and it finally fired up - for 15 seconds, then fizzled. Twenty more pulls resulted in nothing.

Same thing the next day - ran for fifteen seconds and fizzled, then wouldn't start again.

Based on the advice of the forum, I went to check the compression, to avoid throwing good money after bad. I went to the local auto z*ne and bought a compression tester.

Not sure whether I did this correctly or not. With the motor cold (my only choice considering it won't run) and no fuel line attached:

----I took one spark plug out and screwed the compression tester snugly into the hole. Pulled the starter five times, and got a reading of 60.

----Did the same thing with the second spark plug hole (with the other spark plug back in), and after five pulls the guage read 60 as well.

I remember reading the guage should read close to 100.

Am I testing the compression correctly?

The motor has sat for some time, and the previous owner said it ran the "last time he tried it".

What would you suggest I do to try and improve the compression?

Thanks!

 

[iwombat]

Re: Help analyzing my compression test (1971 6hp Evinrude Fisherman)

With a pull start of that vintage 60 might be about right. You'd get better readings with BOTH plugs out. You'd also get better readings with a rope around the flywheel instead of the rope starter. The key there is that both readings are even. I'd consider it well worth putting some time and effort into.

 

[Rick.]

Re: Help analyzing my compression test (1971 6hp Evinrude Fisherman)

Here is the way I was told to check outboard compression. Pull both plugs. Put the gauge on the top cyl. and pull briskly until gauge stops climbing. Write down the number and move the gauge to the bottom hole. Pull the rope briskly the same number of pulls that you did for the top hole. Write down the number and that is your compression. Once you get it running do a seafoam treatment to clean out the rings and cylinders. I did a seafoam on my 4hp and was disappointed that it didn't smoke that much. Later on I rechecked the compression and it had gone up almost 15lbs./cyl. so the seafoam must have unstuck the rings. I hope your using fresh gas/oil mix. You should probably clean and rebuild the carb. next. I suppose 60 isn't the greatest reading but I'll bet it will be a good motor for you even at that. Best of luck. Rick.

 

[wbeaton]

Re: Help analyzing my compression test (1971 6hp Evinrude Fisherman)

Ground the plugs when you are testing the compression so you don't fry the coils.

60 psi is low, but it'll run on it. Any lower and you'll have problems.