2 Ring Sets .010 77.25mm Fit Kohler 24-108-24-S

Two piston ring sets at .010 inch oversize for Kohler 77mm twin-cylinder engines. Replaces 24-108-24-S. Finished bore 77.25mm. TWO SETS, ONE ENGINE. One ring set does one cylinder. These are twins, so two sets complete an engine, and there are two in the box. FITS the 624cc / 77mm twins: CH18, CH20, CH22, CH620, CH621, CH640, CH641, and the CV equivalents CV18, CV20, CV22, CV620, CV621, CV640 and CV641. BUT CHECK YOUR DISPLACEMENT FIRST. This is the real question on these engines, and it is not the one most listings ask. CH22, CV22, CH620, CH640, CV620 and CV640 were each built in TWO sizes - 624cc on a 77mm bore, and 674cc on an 80mm bore. The model number is the same. The engines are not. Look up your engine's spec number, or its displacement, before ordering. THERE IS NO STYLE A / STYLE B QUESTION ON 77mm ENGINES. The factory parts data for a 77mm engine lists a single ring ladder and a single piston ladder, and the service manual's Piston Style A clearance table covers the entire 77mm group. The Style A and Style B split that matters so much on the 80mm and 83mm engines simply does not exist here. You do not need to measure a ring. THE 77mm RING LADDER: 24-108-22-S, standard, 77.00mm; 24-108-23-S, 0.08mm (.003 inch), 77.08mm; 24-108-24-S, 0.25mm (.010 inch), 77.25mm, THIS SET; 24-108-25-S, 0.50mm (.020 inch), 77.50mm. The factory writes these oversizes in millimeters. Their (.08) means 0.08 millimeters, which is .003 of an inch - not .008 of an inch. It is a very easy misreading and it appears all over the aftermarket. The factory oversizes for this family stop at .020 (0.50mm). ON ASSEMBLY. Square each ring in its own bore and check the end gap before fitting it to a piston. Stagger the gaps on installation. Hone the bores first so the rings have a crosshatch to bed into.

• TWO RING SETS AT .010 OVERSIZE - ONE COMPLETE TWIN - Finished bore 77.25mm. Replaces Kohler 24-108-24-S. One set does one cylinder and there are two in the box, so a whole engine is one order. For 77mm twins that have been bored .010 over.
• CHECK YOUR DISPLACEMENT, NOT YOUR RING THICKNESS - CH22, CV22, CH620, CH640, CV620 and CV640 were built in BOTH 77mm and 80mm. Same model numbers, two different engines. The 77mm is 624cc and the 80mm is 674cc. Look up your engine's spec number or displacement before ordering - the model number alone will not settle it.
• THERE IS NO STYLE A OR STYLE B ON THE 77mm ENGINES - so there is nothing to measure. Kohler's parts data for a 77mm engine lists one ring ladder and one piston ladder, and the service manual's Style A table covers the whole 77mm group. The Style A and Style B split is real on the 80mm and 83mm engines. It is not real here, and you do not need to pull a ring to check.
• THE FULL 77mm LADDER, AND A NOTE ON KOHLER'S NUMBERING - 24-108-22-S is standard at 77.00mm. 24-108-23-S is 77.08mm. 24-108-24-S is 77.25mm, which is this set. 24-108-25-S is 77.50mm. The factory writes those oversizes in MILLIMETERS, so their (.08) is 0.08mm which is .003 inch, and their (.25) is 0.25mm which is .010 inch. The factory oversizes for this family stop at .020 (0.50mm).
• ON ASSEMBLY - Check ring end gap with each ring squared in its own bore before you fit it to a piston, and stagger the gaps around the piston on installation. Hone the bores so the new rings have a crosshatch to bed into. Rings cure oil burning on a bore that is still round and within taper; on a glazed or scored bore they will not seal.