compression charts for motors

tav

Petty Officer 1st Class
Joined
Feb 8, 2008
Messages
239
looking at used boat and it has a 2001 merc 125 o/b,,,,,comp. is 95,105,105,100.....yes or no.
are there charts for compression for various motors....thanks
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,721
The rule of thumb is no single cylinder will be more then 10 percent away from the highest. Highest 105 so no lower then 90.5, and it looks like your good for low hour motors. For high hours you can expect 20 percent
 
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