Oversize overhaul package for the 83mm Kohler twin cylinder engines, supplied at 83.50mm, which is Kohler's +0.50mm oversize and the step commonly called .020 over. This kit is for an engine whose cylinders have already been machined to that oversize. If your block is still at the 83.00mm standard bore, the standard kit is the one you want. Contents: two 83.50mm pistons with matched ring sets, replacing 25 874 17-S on the 725cc engines and 25 874 20-S on the 747cc engines, with rings replacing 25 108 04-S; a complete gasket and seal set replacing 24 755 394-S, which supersedes 24 755 207-S; both crankshaft seals; and a tube of crankcase sealant for the closure plate and oil pan. The pistons and rings arrive as a matched set, so there is no ring style to identify and nothing to measure on the old piston before ordering. Covers Command and Command Pro CH25, CH26, CH730, CH735, CH740, CH745, CH750 and CH752, vertical shaft CV25, CV26, CV730, CV735, CV740, CV745 and CV750, and Courage twins SV710 through SV740 and SV810 through SV840. The liquid cooled LH755 and LH775 are a separate engine family and are not covered. Identify the engine from the model and spec numbers on the blower housing decal rather than by horsepower. Not included: connecting rods, bearings, valves, camshaft or oil pump. Before assembly, check ring end gap in the finished bore and ring side clearance in the piston grooves, and make sure the shop has left a honed finish for the rings to seat against.
- THE .020 OVER KIT - 83.50mm PISTONS - These measure 83.50mm, which is Kohler's +0.50mm step, the one the trade calls .020 over. They are for a block that has already been bored to match, and they will not go into a standard 83.00mm cylinder. If yours is still standard, or has not been measured yet, our standard-bore 83.00mm overhaul kit is the one to order - then keep this page for after the machine shop has finished. Take the old piston with you so the shop can bore to it.
- WHAT IS IN THE BOX, WITH THE NUMBERS - Two 83.50mm pistons, each with its own ring set, replacing Kohler 25 874 17-S on the 725cc engines and 25 874 20-S on the 747cc engines. The rings replace 25 108 04-S. Full gasket and seal set replacing 24 755 394-S, which supersedes 24 755 207-S. Both crankshaft seals. One tube of crankcase sealant for the closure plate and oil pan joint. No connecting rods, no bearings, no valves and no camshaft - this is a top end and gasket package.
- ONE PISTON COVERS BOTH DISPLACEMENTS - Kohler splits the 83mm twins into 725cc and 747cc and lists a different piston for each. The piston in this kit serves both, and we have shipped it for both for years. That means you do not need to work out which displacement you have before ordering. You do need to know the bore, and the bore is the only measurement that matters here.
- FITS THE 83MM KOHLER TWINS - Command and Command Pro CH25, CH26, CH730, CH735, CH740, CH745, CH750 and CH752. Vertical shaft CV25, CV26, CV730, CV735, CV740, CV745 and CV750. Courage twins SV710 through SV740 and SV810 through SV840. The liquid cooled LH755 and LH775 are a different engine family and are not covered. Read the model and spec numbers off the blower housing decal rather than going by horsepower, because the same horsepower was sold on more than one block.
- WHILE IT IS APART - Check ring end gap in the bore the rings will actually run in, and check side clearance in the piston grooves before anything goes together. Make sure the shop left a honed finish for the rings to seat against. The Command twins run hydraulic lifters, so there is no lash to set on those; the Courage SV twins are mechanical and do need lash set cold. Clean the closure plate and oil pan faces back to bare metal before the sealant goes on, and let it set up before you add oil.