Harley-Davidson equips its Electra Glide motorcycles with the Big-Twin engine, which has the transmission separate from the engine case. Power from the engine drive sprocket flows to the transmission via a primary drive chain. The primary drive chain connects the engine drive sprocket to the clutch and is subjected to heavy loads when accelerating or using compression braking. Primary chains gradually stretch under these loads and require adjustment to maintain the proper amount of chain “free play.”
1. Remove the negative battery cable bolt from the battery terminal with a wrench. Pull the negative cable off the battery terminal.
2. Place a bike lift under the frame toward the rear of the bike. Lift the bike so that the rear wheel is off the ground and the bike is stable.
3. Remove the primary chain inspection cover screws with a ratchet and Allen driver. Pull the inspection cover and gasket off the primary cover.
4. Locate the tightest spot in the primary chain. Place the transmission into 1st gear with the shift lever. Rotate the rear wheel forward while checking the chain free play (up-and-down movement). Stop the chain with the tightest point at the top of the inspection hole.
5. Loosen the primary chain tensioner nut with a wrench. Slide the tensioner upward to tighten the primary chain. Tighten the tensioner nut lightly with a wrench and check the free play. The specifications are 5/8 inch to 7/8 inch if the engine is cold and 3/8 inch to 5/8 inch if the engine is hot.
6. Adjust the tensioner in small increments until the desired measurement is achieved. Torque the tensioner nut to 21 to 29 pound-feet with a torque wrench and socket, then recheck the free play.
7. Position the inspection cover and new cover gasket over the inspection hole. Install and torque the inspection cover screws to 50 to 70 pound-inches with a torque wrench and Allen driver.