According to the Nov, 1952 Cycle magazine (not necessarily the definitive source, but best I can do), here are the 2-way motorcycle records set in 1952:
61 cu in (1000cc) Marty Dickerson, Vincent, 142.72mph
40 cu in (650cc) Henry Bernal, Triumph, 144.338mph
30.50 cu in (500cc) Bud Hare, Triumph, 134.597mph
21 cu in (350cc) Lloyd Bulmer, Velocette KSS, 119.87mph
15 cu in (250cc) Delbert Branson, Indian, 80.62mph
Some one-way speeds were:
Marty Dickerson, 1000cc Vincent - 144.98
Tom Smith, 650cc Triumph - 147.78
Bobbie Kelton, Brute - Bud Hood, CB Clausen 95 cu in? Harley - 168.77
Jim Hunter, 80cu in Harley - 150.75
Mike Tucker, 45cu in Indian - 117.64