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When replacing outboard pistons, the cylinder should generally be honed to ensure the rings wear into the cylinder, weal well, and lubricate well. Honing is the final step in an engine rebuild. It involves putting a 45-degree crosshatch pattern in the cylinder. You can do this at home.


Our Mercury V6 steel sleeve ball hones are easy to use and provide many advantages including; 1) removing amorphous material from the bore while retaining pockets for lubrication, 2) creating a clean, partial-plateau surface after boring or simply re-ringing your motor, and 3) help chamfer the edges of the ports to improve performance increasing oil retention and extending the life of your engine.


While more aggressive and expensive stone hones, like the Sunnen Hone, will help true a bore, ball hones have been successfully used by race motor builders since the 1970s to deglaze and ready a block to build.


In April 1984, an APBA and U.I.M. OZ World Kilo record of 157.425 mph was set by engine builder Dick O'Dea. He started with a stock 2.4 Liter Mercury 200 HP. As a kid,  I watched him use ball hone on the final finish in his shop in Gasoline Alley in Patterson, NJ.


To use a ball hone, you can follow these steps: 

  1. Heavily coat cylinder walls with honing oil, WD-40, or non-synthetic 2-stroke or engine oil.
  2. Install the honing tool on a power drill.
  3. Insert the hone into the cylinder and maintain a medium drill speed.
  4. Quickly move the drill up and down inside the cylinder about 6 times.
  5. Remove the hone and check the bore for a good even pattern.
  6. Reverse the drill and repeat the process if there are still glazed.

You can achieve a cross-hatching pattern of 45 degrees by matching your stroke speed and rpm. You can see the lines of oil moving in the pattern that you're running. If it's not about 45 degrees, you can change your rpm or stroke speed to match that.

You can use a spindle speed between 500 and 800 rpm. You should never exceed 1200 rpm. The ball hone tool should have a smooth continuous stroke rate between 120 and 180 inches per minute. 

You can clean the cylinder ID with warm soapy water and a nylon brush. After drying, you can continue to clean the side of the cylinder with a lint-free cloth until the cloth comes out clean lightly. Coat with oil heavily quickly to avoid rust developing.


Includes one (1) Ball Hone sized for a Mercury 2.5 Liter Outboard, made in the USA.


Contact Mike Hill at

Ball Hone, Mercury 2.5 Liter

SKU: BH-77
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