Engine rebuild kit for Kohler K-Series and Magnum twin-cylinder engines on the 3.125 inch bore. What is in the box, with the numbers for the parts bin: Gasket set with crankshaft seals and intake valve seals - Kohler 25-755-37-S, 26 pieces Two standard connecting rods - Kohler 52-067-67-S Two standard piston ring sets - Kohler 52-108-09-S Quantities are for a complete twin. Two rods and two ring sets, not one of each. Fits KT17, KT19, M18, M20, MV16, MV18 and MV20. All seven are 3.125 inch bore engines, which is why one kit covers the lot. KT17, M18, MV16 and MV18 are identical in bore and stroke at 3.125 by 2.750, 42.18 cubic inches. KT19, M20 and MV20 share the same bore with a longer 3.062 stroke. Two things to check before ordering, and they are the two that cause almost every wrong order on this family. First, the rings are standard size. If the block has already been bored, they will not seal. Kohler service sizes here are true inch - .003, .010, .020 and .030 over - not millimeters. Anyone used to metric oversizes will expect millimeters here, and there are none on this engine. Measure the bore after machining and order to what you measure, not to what you asked the shop for. And note that .003 is a production size rather than a rebore step, so do not read the ladder as a sequence. Second, identify the piston rather than the engine tag. Kohler changed piston crown and ring-land design partway through production without changing the model designation, so two engines wearing the same badge can take different rings. Pull a piston and look at it. No pistons and no valves in this kit. Pistons, valves, valve springs, stem seals, lifters, camshaft and oil pump are not included. Standard pistons for this bore are 52-874-11-S.
- WHAT IS IN THE BOX, WITH THE PART NUMBERS - Gasket set with crankshaft seals and intake valve seals, Kohler 25-755-37-S, 26 pieces. Two standard connecting rods, Kohler 52-067-67-S. Two standard piston ring sets, Kohler 52-108-09-S. Quantities are for a complete twin - two rods and two ring sets, not one of each.
- FITS ALL SEVEN 3.125 INCH KOHLER TWINS - KT17, KT19, M18, M20, MV16, MV18 and MV20. Every one of them is a 3.125 inch bore, so the pistons, rings, rods and gaskets are common across the whole family. KT17, M18, MV16 and MV18 are also identical in stroke at 2.750 and 42.18 cubic inches; KT19, M20 and MV20 share the bore with a longer 3.062 stroke.
- STANDARD SIZE RINGS - MEASURE YOUR BORE FIRST - These are standard bore ring sets. If the block has been bored oversize they will not seal. Kohler service sizes on this family are TRUE INCH - .003, .010, .020 and .030 - not metric. Anyone used to metric oversizes expects millimeters here and there are none.
- IDENTIFY THE PISTON, NOT THE ENGINE TAG - Kohler changed piston and ring-land design during production without changing the model designation. Pull a piston and look at it before you order rings. Ordering by horsepower or by the engine tag alone is the most common reason a ring set turns up that will not fit the lands.
- NO PISTONS AND NO VALVES IN THIS KIT - This is a gasket, rod and ring kit. Pistons, valves, valve springs, stem seals, lifters, the camshaft and the oil pump are not included. If the pistons are scored or the lands are worn, order pistons separately - standard is 52-874-11-S.