1980 140 evinrude, bored 030 low compression on all 4 really low on #1

[SparkieBoat]

I do not know the history of this motor but it came to me with one head off. the pistons were stamped 030. head looked fine and cylinder walls looked ok. new head gasket and I got 100 PSI on 3 and the top starboard had 75. I got a feeling that this motor was rebuilt by some jackleg. but not sure. any ideas what I should look for to figure out this low compression problem without tearing the engine down?

 

[Bosunsmate]

remove bypass cover for that cylinder and inspect rings

 

[emdsapmgr]

That engine when new probably had over 125# compression on each cyl. 100 is low to start with, let alone the 75 on one hole.

 

[SparkieBoat]

yes. that is what I figured. I was wondering if maybe the bore job was a little over or the rings a little under or something like that. maybe it ran hot and got out of round. I will probably just use it as a parts motor. I got 2 more on the yard with great compression.
They just are not worth the time and money to rebuild.
this motor had very low hours after the rebuild from what I was told

 

[V153]

I got a feeling that this motor was rebuilt by some jackleg

Evidently ...