2006 Mercury 90 HP 4 stroke EFI - Compression?

[jaymoussy]

I am buying a used boat with a 2006 Mercury 90 HP 4 stroke EFI, and will have a compression test done.

I believe, for reading here, that nominal compression should be 138 psi.

- is above compression figure correct?
- how far off could it be, and still be acceptable?
- acceptable variation across cylinders?

(I will have a question about basic initial "looking things over, getting to know your motor" in another post)

 

[1nebel0]

They need to be 15% of the lowest to the highest cylinder....I have the 115 four stroke and that number is about where my cylinders are at..

 

[jaymoussy]

I was away, not present when brokerage had compression test done.
Sales guy calls my wife and says to her that the compression is fine... 230, 240 psi

Strange. These are racing engine kind of specs.
What am I (newbie) missing here...?

I will get to visit tomorrow in person, but that is puzzling...

 

[1nebel0]

Let us know the outcome...those numbers are wrong..........

 

[jaymoussy]

Well I have seen the printout: 235, 240, 240, 240

Talked to shop guys, they confirmed this is normal range for this type of motor (2006 90 HP Merc, 4-stroke EFI). Even said should not be under 180, would make motor hard to start.

Purchase is conditional to compression test.... and I am totally confused...!!

 

[jaymoussy]

UPDATE: talked to a marine broker I met, and he seems to say these numbers aren't right.

Very confused first timer here... not the best start to a new hobby.

UPDATE no. 2: We are redoing the compression test!