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View Full Version : Mercury 2.5 245HP powerhead


Restless80SHADOW
09-28-2021, 07:27 PM
Mercury 2.5 powerhead. Complete drop on. I bought this as a fresh rebuild. It has never been fired. Piston tops are clean and shiny. By the markings on the block, it was most likely done .020 over. Has lightweight flywheel. Located in NJ
$4,500.00
493671493672493673493674493675493675493676493677
Mrzip
10-10-2021, 04:27 PM
Nice & Clean :)
TEXAS20225
10-11-2021, 04:27 PM
must be steel steel sleeves
Restless80SHADOW
10-12-2021, 06:34 PM
494597494598494599494600
Pulled the heads. All holes appear to be steel based on the cross hatching in the cylinders. All holes are 20 over. Pistons are all Promarine based on the part numbers. Block is a clean freshwater block based on the water passages. The heads were also decked based on the hatching on them as well. Will need head gaskets unless I can track down a replacement set.
rjdubiel
10-21-2021, 08:36 AM
Looks like a nikasil. What do the bores measure? GLWS, these are great motors and are very strong.
Air It Out
10-21-2021, 08:12 PM
Is this a big bearing or small bearing powerhead?
Qshot1989
10-22-2021, 10:44 AM
Is this a big bearing or small bearing powerhead?

My guess would be small. What are guys doing for steel sleeve motors to make them work well from a cooling perspective if you are runing a 1 piece adapter plate?
rjdubiel
10-22-2021, 07:15 PM
Small holes out the adapter plate and keep it warm and regulate the water using poppet dump. And more clearance on the piston to cylinder.
http://www.us1.cc/racingcoolingsystem.html
Schramer
10-22-2021, 11:39 PM
Small bearing unless it was modified for a big bearing & the crank was sleeved or changed. That has got to be a plated .020 over motor.....those sleeves do not like like cast iron liners to me...?
Qshot1989
10-23-2021, 09:03 PM
Small holes out the adapter plate and keep it warm and regulate the water using poppet dump. And more clearance on the piston to cylinder.
http://www.us1.cc/racingcoolingsystem.html

You mean by running a larger ring gap?
rjdubiel
10-24-2021, 07:55 AM
Ring gap is based of bore size. All depends on Pistons too. Forged Pistons need to add .003 to the piston to cylinder clearance. The piston will heat and swell faster than the steel sleeve so need the extra clearance to not scuff
rjdubiel
10-24-2021, 08:08 AM
Low rpm this info is not needed. 7 to 8k plus do some reading for steel bore with forged Pistons
495194
rjdubiel
10-24-2021, 08:09 AM
Back to this for sale post. Has the seller replied to anyone?
Restless80SHADOW
10-25-2021, 06:46 AM
I replied to all my PM's.
Like I said in the first and second post, I did not build the motor nor have someone build it for me. I bought it just as you see it, so I am not sure on the specs as to the bearing size. all 6 sleeves are steel.
25two.stroke
10-25-2021, 08:25 PM
Interested, how long would you be willing to hold it if you got a down payment? I live in Cali and have family in NJ...not sure when I would make it out that way next.
sick_nick
10-26-2021, 08:28 AM
494597494598494599494600

Pulled the heads. All holes appear to be steel based on the cross hatching in the cylinders. All holes are 20 over. Pistons are all Promarine based on the part numbers. Block is a clean freshwater block based on the water passages. The heads were also decked based on the hatching on them as well. Will need head gaskets unless I can track down a replacement set.


PM sent!
Restless80SHADOW
11-18-2021, 10:54 AM
Bump to the top
tabme
11-26-2021, 02:35 PM
Just want to say Big Thank You to Justin. You were a gentleman with the purchase and appreciate the help loading the power head. Thanks Again