How do I do a compression check

Mscanon99

Petty Officer 2nd Class
Joined
Sep 10, 2007
Messages
122
Hi All,

I looked throughout the site and could not find this, maybe I missed it.

I want to do a compression check on my 1994 Evinrude 115. I purchased a compression tester from a local auto parts store. It looks like it will work, has severa connectors with a hose and the guage.

Does anyone have the step by step instructions for properly doing a compression check.

Thanks to all,

Best,

MS
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Re: How do I do a compression check

Remove all spark plugs
Ground all spark plug wires...or pull the lanyard off the kill switch..or both.
Put gage in one cylinder's spark plug hole
Crank engine with ignition key several revolutions, till gage doesn't go any higher.
Read and record results
Repeat with the rest of the cylinders.

Don't squirt oil in the cylinders, that's cheating
It is NOT necessary to block the throttle open on a two stroke regardless of what somebody will tell you.
 

Mscanon99

Petty Officer 2nd Class
Joined
Sep 10, 2007
Messages
122
Re: How do I do a compression check

Thanks.

Quick follow up question, should I warm the motor up first?

MS
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Re: How do I do a compression check

Thanks.

Quick follow up question, should I warm the motor up first?

MS

Since a compression check is the first step in servicing a motor and since often times the motor won't even run at that point, obviously the compression check is done on a cold motor.

But if for some reason you think it is changing when it warms up, go ahead and do it again.
 
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