BSA Pre-Unit Singles "Big End" Assembly (1) - B31 / B33 / M20 / M21 / Etc (PRE - 1959)

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  • $ 199.95
  • Regular price $ 208.65
  • 1 available

Worn big end? Bottom end making a "knocking sound"? Chances are your big end is in need of replacement! Replace your big end with our new high quality English made complete big end assembly's. Comes included with pin, rollers, race, nuts, etc.


Works with connecting rod part #'s: 66-483, 65-1614, 66-481. Fits all BSA pre-unit singles (B31, B32, B33, M20, M21, M22, etc) from approx 1937-1958. Check your parts book to ensure the best fitment.


  • Made in England
  • OEM part number is B14,66-483,65-1614,66-481
  • Free shipping in the USA