1996 Mercury 25 compression spec?

[Bowhunter1661]

Just curious if anyone knows the spec for these motors. This motor has the chrome cylinder bores as well, not standard steel. I am looking to buy the motor from a guy in Missouri but when he tested it on came back at 91 on bottom and 97 on top (This was cold and not oiled). I have tested a few motors in the past and almost all were in the 120 range. I have no experience with chrome lined bores not sure if they need to be hot or oiled..

 

[Skiffing]

I'm not surprised by those low readings. The test was done incorrectly.

According to the 1996 merc manual for 25 hp 2 cycle max compression is 180 psi. Minimum is 127 psi. Below 120 indicates problems. No more than 15% difference between cylinders.

This manual is on boatinfo.no

Procedure:

Run engine until thermostat opens.

Remove all plugs. Hit kill switch.

Install gauge.

Open throttle plate to WOT and crank. Stop when highest reading is achieved.

Rinse and repeat.

 

[Bowhunter1661]

Excellent, that is exactly what I needed. Does anyone know anything about there motors? Are they decent? Last awhile? Not too sure about the coated aluminum cylinders on these motors..

 

[jethro]

My boat has a '95 and I don't think it has the nickel cyl bores but regardless it's been a fantastic motor. Flawless so far, many, many hours of trolling.