All Sportster models built after 1984 are powered by Harley-Davidson’s Evolution engine. Unlike the other models in Harley-Davidson’s lineup, which use a three-part engine, primary drive and transmission system, the Sportster houses the engine and transmission in the same unit. The primary drive, which transfers engine power to the transmission, also houses the motorcycle’s manually operated clutch. Over time, the plates within the clutch can wear and allow the clutch to slip, a condition that presents itself as a lack of acceleration while the engine is racing. Repairing the clutch requires a few specialized tool and the partial disassembly of the primary drive.
1. Park the Sportster on its side stand with the ignition off. Shift the transmission into fifth gear. Mount the Sportster on a service stand to hold it in a vertical position.
2. Remove the bolt from the rear of the seat, using a screwdriver or by hand. Pull the left side cover off the Sportster’s frame, then remove the large Maxi-fuse from the separate fuse holder along the side of the fuse box.
3. Unbolt the left footrest from the Sportster’s frame, using a Torx driver. Remove the shift lever pinch bolt, located at the center of the primary drive cover on the left side of the Sportster, using a combination wrench. Pull the shift lever off the shifter shaft.
4. Place a drain pan below the round clutch inspection cover at the rear portion of the primary drive cover. Remove the drain bolt, located directly under the clutch inspection cover, using a Torx driver. Let the primary fluid drain until the flow of oil reduces to a light drip. Screw the drain bolt into place once the primary fluid has drained completely, then tighten the bolt to between 14 and 30 foot-pounds, using a torque wrench.
5. Pull the rubber boot of the cable adjuster at the middle of the clutch cable, located near the left front frame tube. Loosen the adjuster lock nut, using an open-end wrench, then turn the adjuster clockwise until it is lightly seated to loosen the clutch cable.
6. Remove the clutch inspection cover and the quad-ring, the square-shaped O-ring that seals the cover against the primary drive, using a Torx driver. Pull the spring and lock plate off the center of the clutch release mechanism by hand.
7. Turn the adjustment screw at the center of the clutch release mechanism clockwise with a flat-head screwdriver until you can pull the clutch cable end out of the catch — or ramp — at the bottom of the mechanism. Hold the screw in place, then remove the screw’s retaining nut with a box-end wrench. Loosen the lock nut securing the clutch cable to the bottom of the primary drive cover, using an open-end wrench. Unscrew the clutch cable from the cover.
8. Loosen the primary chain adjuster lock nut on the bottom of the primary drive cover, using open-end wrench. Turn the primary chain adjuster counterclockwise until the primary chain is completely loosened.
9. Remove the primary drive cover from the inner primary drive housing, using a Torx driver. Pull the clutch release mechanism off the adjustment screw.
10. Place a Harley-Davidson sprocket locking link between the engine sprocket and the clutch assembly inside the inner primary drive housing.
11. Remove the snap ring securing the clutch release plate and the adjustment screw to the clutch assembly, using internal snap ring pliers. Pull the screw and release plate out of the clutch assembly. Turn the nut at the center of the clutch assembly clockwise to loosen it, using an impact wrench. The nut has a left-hand thread; do not turn the nut counterclockwise to loosen it from the transmission shaft. Unscrew the nut completely. Push the clutch release plate back into place at the center of the clutch assembly.
12. Screw the forcing screw from the spring compressor tool into the clutch release plate. Place the compression tool body over the end of the forcing screw, then screw the handle into place over the body. Turn the handle clockwise to compress the clutch pressure plate and diaphragm spring until you can remove the pressure plate snap ring, using needle-nose pliers. Pull the tool, pressure plate and diaphragm spring out of the clutch assembly. Do not remove the tool from the clutch release plate.
13. Pull all 15 clutch plates out of the clutch assembly. Remove the spring plate from between the fourth and fifth fiber friction plates. Discard the old clutch plates, but retain the spring plate. Check the spring plate for obvious signs of damage, such as cracking or missing rivets. Replace the spring plate if it is damaged in any way.
14. Soak the replacement fiber friction plates and steel plates in Harley-Davidson Sport-Trans fluid for five minutes. Install the a fiber friction plate, followed by a steel plate into the clutch assembly. Alternate between fiber and steel plates until you have installed the fourth friction plate. Place the spring plate into the clutch assembly, then install the remaining clutch plates, starting with a fiber friction plate.
15. Reinstall the clutch pressure plate and diaphragm spring into the clutch assembly. Compress the diaphragm spring, using the spring compressor tool, then insert the snap ring against the pressure plate. Remove the compressor tool and clutch release plate, then unscrew the tool from the adjustment screw.
16. Tighten the clutch assembly lock nut counterclockwise to between 70 and 80 foot-pounds. Tighten the engine sprocket nut to between 190 and 210 foot-pounds. Pull the sprocket locking link out from between the engine sprocket and the clutch assembly. Push the clutch release plate into the clutch assembly. Insert a new snap ring over the clutch release plate, using internal snap ring pliers.
17.Reinstall the primary drive cover. Tighten the cover bolts to between 100 and 120 inch-pounds, using a crisscross pattern to evenly tighten the cover onto the inner primary drive housing. Screw the clutch cable into the bottom of the primary drive cover until it is fully seated. Tighten the cable against the primary drive cover to between 36 and 60 inch-pounds.
18. Turn the clutch release adjustment screw counterclockwise until you can hook the end of the clutch cable over the clutch release ramp. Screw the retaining nut over the end of the adjustment screw. Turn the adjustment screw counterclockwise until you feel resistance, then turn it clockwise a quarter turn. Place the spring and lock plate over the clutch release mechanism.
19. Fill the primary drive with Harley-Davidson Sport-Trans fluid. Stop when the fluid level is just below the clutch pressure plate. Reinstall the clutch inspection cover and a new quad-ring. Tighten the cover bolts to between 84 and 108 inch-pounds, alternating between bolts in a crisscross pattern.
20. Remove the smaller primary chain inspection cover from the top of the primary drive cover, using a Torx driver. Turn the primary chain adjuster clockwise until the primary chain can be moved vertically between three-eighths to a half-inch by hand. Tighten the adjuster lock nut to between 20 and 25 foot-pounds. Reinstall the primary chain inspection cover, then tighten the cover bolts to between 84 and 108 inch-pounds.
21. Pull in the clutch lever until you feel resistance, then measure the gap between the clutch lever and the clutch lever perch. Ideally, there should be a 1/8-inch gap. Turn the cable adjuster at the middle of the clutch cable counterclockwise to tighten the cable until the gap is set to 1/8-inch. Tighten the cable adjuster lock nut, then pull the rubber boot over the adjuster.
22. Push the shift lever onto the shifter shaft at the center of the primary drive cover. Tighten the shift lever pinch bolt. Reinstall the left foot rest bracket onto the Sportster’s frame. Tighten the bracket bolts to between 45 and 50 foot-pounds.
23. Remove the Sportster from the service stand, then lower it onto its side stand.