New Triumph CEI 650 Twins Flywheel To Crankshaft Mounting Bolt. We understand how important this bolt is! Which is exactly why it is made from the correct materials to width stand the pressure and stress it will endure! Measures 3/8″ with a thread pitch of 26 (CEI). Fits Triumph 650 Pre-Unit Twins (Bonneville, T120, T110, 6T & TR6) from 1958-1962 with “Two-Piece” & “One Piece” cranks from 1958-1962. Also fits Triumph 650 Unit Twins (Bonneville, T120, TR6, Tiger, T120TT, T120C, TR6C, TR6SR, 6T & Trophy) models from 1963-1970 only. Please refer to your parts catalog for proper fitment.*****Please ensure that your crankshaft can accept a 5/16″ 26 T.P.I. bolt for the years listed abouve!*****Made in EnglandO.E.M Part number is 70-3907 or 70-6328