• I May of 1981, the MoCo issued a bulletin stating that product and quality improvements have brought about a commonized flywheel taper design. All tapers have were communized at 6° and all keyways were standardized. ¹⁾
  • This was a running change in 1340cc and 1000cc engines but both new and old designs were used in production until the old stock parts ran out.
  • Even though the assembly and disassembly was the same for the old and new style flywheels, the torque values did change for the new style assembly. However, new and old style components must not be intermixed.

Changes for Sportster 1000 engines include:

• In a letter dated May 9, 1977, an HD interoffice memo was sent regarding an inspection of parts stock roller bearings. Some roller bearing part numbers were found to have incorrect diameters. A new micrometer was purchased to remedy this problem.
• Two of those part numbers are gear shaft (9421) and crank pin front rollers (9150A) for Sportsters.
• In light of this oversight, a listing of part numbers with their correct dims and tolerances was issued as in below: