Complete rebuild kit for the 624cc Kohler Command and Command Pro V-twin at standard 77mm bore. The engine is 77mm bore by 67mm stroke. CONTENTS. Two piston and ring assemblies replacing Kohler 24 874 46-S, standard 77mm, with piston pins and circlips. Rings alone are 24 108 22-S. Two connecting rods replacing 25 067 04-S. Two intake valves, 24 017 01-S. Two exhaust valves, 32 016 01-S, a number also catalogued as 24 016 01-S - the two are the same part, 32 016 01-S being the current one. The valves are supplied bare: no valve springs, retainers or keepers are included. Two intake valve stem seals, 25 032 14-S, also catalogued 24 032 05-S and 66 032 05-S. One per cylinder, which is a complete set for this engine: these Kohler twins carry a stem seal on the intake valve only. The intake stroke pulls a vacuum that will draw oil down the valve stem, which is what the seal is there to stop; the exhaust port is under pressure when the engine is running and runs without one. Do not fit a spare seal to an exhaust valve. A gasket set covering both cylinder heads, the Kohler head gasket kit for a single head being 24 841 01-S. Both crankshaft seals, which are different sizes: 25 032 06-S at the PTO end and 24 032 19-S at the flywheel end. One tube of high-torque RTV gasket maker for the crankcase joint. CHECK THE DISPLACEMENT BEFORE ORDERING. Kohler built the CH22, the CH620 and the CH640 in two different bores, and the engine model number alone will not tell you which one you have. 624cc is 77mm and is what this kit fits. 674cc is 80mm and takes different parts. 725cc is 83mm. The displacement is stamped on the engine nameplate; Kohler's service manual states that the 620 and 640 changed from 624cc to 674cc during production and that the nameplate is where to confirm it. If the nameplate has gone, measure the bore - 77.000 to 77.025mm on a new cylinder, 77.063mm being the wear limit. ENGINES COVERED at 624cc and 77mm: horizontal shaft CH18, CH20, CH22, CH620, CH621, CH640, CH641; vertical shaft CV18, CV20, CV22, CV620, CV621, CV640. These are four cycle OHV twin cylinder engines with cast iron liners in an aluminum block, rated between 18 and 22 horsepower depending on model and year. OVERSIZE. Kohler's oversizes on this engine are metric, not inch: plus 0.08mm, plus 0.25mm which is approximately .010 over, and plus 0.50mm which is approximately .020 over. This kit is standard bore. NOT INCLUDED. Valve springs, retainers and keepers; the cylinder heads, camshaft, crankshaft and oil pump. The kit assumes the bottom end is serviceable, so inspect the connecting rod journals and the crankcase sleeve bearings before ordering. REBUILD FIGURES from the Kohler service manual. Cylinder head bolts in two steps, 200 inch pounds then 370 inch pounds; head nuts 150 then 315. Connecting rod cap 200 inch pounds on the 8mm straight shank bolt. Flywheel screw 49 foot pounds. Closure plate fasteners 216 inch pounds. Ring end gap 0.25 to 0.45mm in a new bore. Piston to bore running clearance 0.039 to 0.082mm. Valve seat angle 45 degrees. Minimum valve lift 8.07mm. These engines run hydraulic lifters, so there is no valve lash adjustment to make. Check ring end gap in the bore each ring will actually run in, use a ring compressor, fit the circlips with the open end away from the ports, and turn the engine over by hand before the first start.
- 77mm REBUILD KIT FOR THE 624cc COMMAND TWIN, WITH RODS AND VALVES - Two standard 77mm pistons with rings, pins and clips, two rods, four valves, both intake stem seals, a gasket set, both crank seals and RTV sealer. Fits the 624cc Kohler Command and Command Pro twins: CH18, CH20, CH22, CH620, CH621, CH640 and CH641, and the vertical shaft CV18, CV20, CV22, CV620, CV621 and CV640. This is the kit for an engine burning oil, down on compression, knocking at the rod or with a scored bore.
- WHAT IS IN THE BOX, WITH THE NUMBERS - Two piston and ring assemblies replacing 24 874 46-S, standard 77mm, with pins and clips; rings alone 24 108 22-S. Two rods, 25 067 04-S. Two intake valves 24 017 01-S and two exhaust 32 016 01-S, bare - no springs, retainers or keepers. Two intake stem seals, 25 032 14-S, one per cylinder. A gasket set for both heads; the single-head kit 24 841 01-S does one. Both crank seals: PTO 25 032 06-S, flywheel 24 032 19-S. One tube of high-torque RTV gasket maker.
- READ THE NAMEPLATE FIRST - 624cc IS 77mm - The CH22, CH620 and CH640 were each built in two different bores. The 624cc version is 77mm and takes this kit. The 674cc version is 80mm and will not. The 725cc is 83mm. Displacement is stamped on the engine nameplate, and Kohler's own service manual says to confirm it there, because the 620 and 640 changed from 624cc to 674cc partway through production. If the nameplate is gone, caliper the bore: 77.000 to 77.025mm new, 77.063mm worn.
- STANDARD BORE, AND WHAT IS NOT IN THE KIT - Pistons are standard 77mm. If the block has been machined, Kohler's oversizes are metric, not inch: plus 0.08mm, plus 0.25mm (about .010 over) and plus 0.50mm (about .020 over). Not included: valve springs, retainers and keepers, the heads, camshaft, crankshaft and oil pump. The kit assumes a serviceable bottom end: check the rod journals and sleeve bearings first. Lil Red Barn also offers a 77mm top end kit without rods or valves, and a ring kit.
- REBUILD FIGURES FROM THE KOHLER SERVICE MANUAL - Head bolts go in two steps, 200 inch pounds then 370. If yours are nuts, 150 then 315. Rod cap 200 inch pounds on the 8mm straight shank. Flywheel screw 49 foot pounds. Closure plate 216 inch pounds. Ring end gap 0.25 to 0.45mm, checked in the bore each ring will run in. Piston to bore clearance 0.039 to 0.082mm. Stem seals fit the intake valves only - the exhaust runs without one. Hydraulic lifters, so no valve lash to set.