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Clutch plug

When Harley replaced the dry clutch with the wet clutch it also moved the release mechanism form the sprocket cover to the primary cover. This plug screws into the primary cover. You remove it to adjust the clutch, in combination with cable adjustment at the primary side of the cable.

37880-71

 Sportster_Engine_Primary_Primary-cover_37880-71_Clutch-plug_1971-1976 Sportster_Engine_Primary_Primary-cover_37880-71_Clutch-plug_1971-1976 Sportster_Engine_Primary_Primary-cover_37880-71_Clutch-plug_1971-1976
Polished aluminum. Harley introduced this plug with the redesigned primary used on wet clutch models. It installs over the clutch adjuster. Unlike the oil-fill primary plug, it is not vented and does not install flush with the cover. Problems: Hard to remove without damaging the slot. There are special tools with the precise shape that can remove the plug with minimum damage.

34742-77B

 Sportster_Engine_Primary_Primary-cover_34742-77B_Primary-plug_1977-1984 Sportster_Engine_Primary_Primary-cover_34742-77B_Primary-plug_1977-1984 Sportster_Engine_Primary_Primary-cover_34742-77B_Primary-plug_1977-1984
Polished aluminum. Used with new cases in 1977. Same as 34742-71 but no vent hole. Vent is provided by vented bolt in top of rear motor mount. Harley introduced this plug with the redesigned primary used on wet clutch models. It installs flush to the primary cover.  also used as the clutch adjustment plug in the primary cover. Problems: Hard to remove without damaging the slot. There are special tools with the precise shape that can remove the plug with minimum damage.