Cylinder Base Large O-Ring on Crankcase Stud 93mm x 2.2mm - purchase 2 to refresh both cylinders.
BMW added an extra O-Ring groove in the cylinder foot in May of 1979. If your (cast iron) cylinder does not have a groove for this O-Ring, then this o-ring does not apply. These only fit on Nikasil Cylinders.
Note that there is a low octane metal base gasket specified for the 1976 R60/6 and 1977 R60/7 that will de-compress other 1976-on airheads, but is generally not needed in the USA.
Vehicle Manufacturer: BMW
Application: BMW Airhead Models
Make/Model: BMW R45, R60, R65, R75, R80, R90, R100
Model Years: 1973 - 1996
Manufacturer #: 11 11 1 337 567