Connecting rod in the first undersize (first bearing undersize) with a red identification mark for powerful single-cylinder Briggs & Stratton four-stroke petrol engines with 10 horsepower (10 HP) and 12.5 horsepower (12.5 HP). The connecting rod is one of the most mechanically stressed components inside the powertrain, responsible for transmitting linear force from the piston to the crankshaft. This high-precision replacement part is purpose-built for installation after the crank pin of the crankshaft has been machined and ground to the first undersize because of wear or ovality. The red mark on the connecting rod serves as a clear visual indicator of the reduced big-end diameter, to avoid assembly errors. Technical specifications (dimensions): Engine manufacturer: Briggs & Stratton Engine power: 10 HP / 12.5 HP (10 HP / 12.5 HP) Size / undersize: First crankshaft bearing undersize (I sp / -.010" undersize) Big-end inner diameter (for the crankshaft): 31.35 mm (factory tolerance for the first undersize) Small-end inner diameter (for the piston pin): 20.4 mm Distance between the inner edges of the bores: 95.0 mm Overall external length of the connecting rod: 175.0 mm Catalogue colour code: Red – visual indicator of the first bearing undersize Part type: High-precision replacement part Material: High-strength aluminium alloy engineered to compensate for strong mechanical and thermal stresses during heavy-duty operation. Compatibility (list of machines and engines): Designed for installation on robust Briggs & Stratton engines with a vertical crankshaft that require a red connecting rod after the first machining of the crankshaft: Briggs & Stratton models: 10 HP and 12.5 HP series (mostly the more robust generations of vertical engines). Application on machines: Riding lawn mowers (riders), large lawn-mowing systems, heavier power tillers and professional generators equipped with this type of powertrain.