Topic: Size Matters

[Phoenix]

There are (4) orings on the head-(2) under the towers and (2) around the oil supression gizmos.  I think it calls for two different sizes.  On the parts fisch, it shows (4) orings-9137-300-003 (3.7 x 1.7).  These are small.  I looked at Hack a Week.  His is two years newer and he uses (4) larger ones-all the same size.
I've been to this rodeo before and the question never came up. Must be a senior moment.  I can't find the answer anywhere.  Any help would be really appreciated.
Thanks,

[bryanj]

All 4 are the same size, i seem to remember very early heads did not have the counterbore for the 2 not round the restrictors which blank off the holes in the towers that make them fit both sides

[newday777]

There are (4) orings on the head-(2) under the towers and (2) around the oil supression gizmos.  I think it calls for two different sizes.  On the parts fisch, it shows (4) orings-9137-300-003 (3.7 x 1.7).  These are small.  I looked at Hack a Week.  His is two years newer and he uses (4) larger ones-all the same size.
I've been to this rodeo before and the question never came up. Must be a senior moment.  I can't find the answer anywhere.  Any help would be really appreciated.
Thanks,

What bike are you asking about???

[Phoenix]

1971 cb750 k1