Hastings, 2-3/4" bore piston ring set. STD

50-73 45" (750cc) Flathead; all 52-56 K 45" (750cc) and KH, KHK 55" (900cc) Flathead models (NU)

Used with late style 1950-1973 type pistons with 1/16" gray iron parkerized compression rings and the 3-piece flex-vent style chrome oil rings. Also fits 52-56 K, KH, KHK 55" (900cc) Flathead models. Std Bore: 2.745" (69.723mm). 1st ring: 1.6mm. 2nd ring: 1.6mm. oil ring: 4.75mm. Note: OEM 1929-1949 pistons are equipped with 3/32" (2.3mm) 1st. & 2nd rings and 1/8" (3.2mm) oil ring, for these Hastings rings see 1950-1973 Flathead model years. These rings will not fit the 1929-1949 early type pistons. Tech tip: Piston grooves vs piston rings. It's not difficult to determine if a Hastings piston ring set will fit a certain piston. You should measure the height of the piston groove in the piston itself. The 2 top grooves will be for compression rings, the lower groove will be for the oil ring. In most cases Hastings oil rings are of the low tension 3-piece flex vent type. Ring heights are listed for reference. Tech tip: Piston oversizes. For each oversize cylinder diameter will increase with .010" (0.254mm). The standard bore of the cylinder is listed for reference. (Tech tip information provided by Hastings Manufacturing Company, Inc.)