.020 Over Piston Kit 47-874-09-S Fits Kohler K301 M12

Complete .020 oversize piston kit that fits Kohler K301 and M12 engines. Replaces part number 47-874-09-S. Contents: piston, matching ring set, wrist pin and wrist pin clips. The ring set on its own is 48-108-03-S, which was previously numbered 235891. One advantage of buying the kit rather than rings alone: More than one piston design was used in these engines, and a bare ring set has to match the piston already in the block. Here the piston and its rings arrive as a matched pair, so that question does not come up. Fits K301, M12 and K532. All three are 3.375 inch standard bore. The K301 is the 12 horsepower single, the M12 is its successor, and the K532 is the 20 horsepower twin - which needs two kits. The near misses, and the K-series is full of them: K241 and M10 - 3.251 inch K301, M12 and K532 - 3.375 inch, this kit K321, M14 and K582 - 3.500 inch K341 and M16 - 3.750 inch Four bores across four model numbers that run consecutively. The K321 is the one people order by mistake, because 301 and 321 look alike on a worn engine tag and the bores are an eighth of an inch apart. This is an oversize piston and the block must already be machined to suit. It will not fit a standard bore, and it is not a way to take up wear in a cylinder that has not been cut. Service sizes on this engine are true inch, not metric: Standard 3.375 inch .010 over 3.385 inch .020 over 3.395 inch .030 over 3.405 inch Take the piston itself to the machine shop so they can measure it and bore to suit, rather than working to a number off a chart. Order to what the bore actually measures when the machining is done. Connecting rod, gaskets, valves and rings in any other size are not included.

• COMPLETE .020 OVERSIZE PISTON KIT - Piston, matching ring set, wrist pin and wrist pin clips. Replaces 47-874-09-S. The ring set on its own is 48-108-03-S, previously numbered 235891. Because the piston and rings ship together as a matched pair, the piston-style question that catches people out on a bare ring order does not arise here.
• FITS KOHLER K301, M12 AND K532 - All three run a 3.375 inch standard bore. The K301 is the 12 horsepower single, the M12 is its successor, and the K532 is the 20 horsepower twin, which needs two kits.
• THE K321 IS NOT THIS PART - K321, M14 and K582 are 3.500 inch. That is an eighth of an inch bigger and it is the most common wrong order in the K-series. K341 and M16 are 3.750 inch. K241 and M10 are 3.251 inch. Four bores, four adjacent model numbers.
• YOUR BLOCK MUST BE BORED TO .020 FIRST - These are oversize pistons. They will not fit a standard cylinder and they are not a way to take up wear in an unbored block. Sizes here are TRUE INCH, not metric: standard 3.375, .010 is 3.385, .020 is 3.395, .030 is 3.405.
• TAKE THE PISTON TO THE MACHINE SHOP - Hand them the actual piston so they can measure it and bore to suit, rather than boring to a number off a chart. Order to what the bore measures after machining, not what you asked for. Connecting rod, gaskets, valves and rings for any other size are not included.