70-1591 C3 H- Hepolite Triumph BSA 500 650 Pre-Unit Unit Crankshaft Main Bearing E1591 67-1240

Hepolite brand main bearing for Triumph and BSA twins in the C3 clearance. These high-quality MJ 1.1/8" ball bearings were used in numerous Triumph 500 and 650 and BSA applications from the 1950's-70s including:

• Triumph Pre-Unit 500 & 650 twins on both timing and drive sides
• Triumph Unit 650 twins 1963-65 on both timing and drive sides
• Triumph Unit 650 twins 1966-71 timing side
• BSA 500 & 650 unit twins 1962-65

Replaces PN# 70-1591 E1591 and 67-1240. Always check your parts book to ensure compatibility.

Note: This bearing was replaced with a metric bearing for the timing side of Triumph 650-750 twins starting at engine #GE27210.

Click Here for the Metric Bearing

Click Here for Drive Side Roller Bearings

A brief note about bearing clearances and British motorcycles: There are up to 3 internal clearances available for Triumph and BSA main bearings. C3 is the loosest clearance, CN (Clearance Normal) is the middle and slightly tighter than C3, C2 is the tightest clearance. Unfortunately there is no definitive guide to what was "correct" for most of these motorcycles, as a rule C3 is generally the safest option when rebuilding your engine.

*Due to their nature we do not accept returns of bearings. If you are unsure which bearing to purchase to suit your application, please reach out prior to purchase.