Clutch adjustment procedures and hardware on all Harley-Davidson Big Twins and Sportsters manufactured since 1990 are identical. Once you learn to adjust the clutch on your bike you can adjust the clutch on any recent Harley. And, with some sight in at least one eye and the slightest practical intelligence you will quickly see how to adjust the clutch on any Harley made since the Second World War. There are only two clutch adjustment specifications for your Custom 1200 Sportster. The first is to adjust the cable lever to 1/8 inch free play. The second is to back out the clutch adjusting screw one half to one full turn. This is how you get there.
Clutch Cable Adjuster Nut
Support your Sportster on a motorcycle jack or secure the front wheel in a motorcycle chock or motorcycle clamp so the bike stands fully upright. Run your hand down the cable that attaches to the clutch housing until your fingers find a bellows-shaped, black, rubber boot. Pull this black boot up to expose a short nut called the cable adjuster nut and a long nut called the cable adjuster locknut. Using two hands, slide an open-end wrench on both nuts and turn the nuts in opposite directions.
Loosen Clutch Cable
Remove the wrenches when the nuts are loose. Turn the small, clutch cable adjuster nut with your fingers until the nut is at the top of the threads and the clutch cable is completely slack. Pull the black sleeve on the top of the clutch cable near the clutch lever away from the clutch housing. Spray aerosol cable lubricant into the sleeve so it will drip down the length of the clutch cable.
Remove Derby Cover
Draw two lines across the derby cover that extend onto the primary cover, with a grease pencil or similar marker, so you will be able to return the derby cover to exactly the same position later. Remove the six Allen-head screws that hold the derby cover in the primary cover with an Allen socket and a socket wrench. Remove the cover. Remove the gasket and throw it away.
Adjust The Clutch
Separate the clutch plates by tightening the clutch adjusting screw, in the exact centre of the clutch, with an Allen wrench. Back out the clutch adjusting screw at least four turns. Tighten the clutch adjusting screw slowly until it just bottoms out. Back out the clutch adjustment screw one-half to one full turn.
Replace Derby Cover
Put a new derby cover gasket on the inside of the derby cover so the red Harley logo on the gasket will face the clutch. Align the holes in the gasket and the cover. Replace the derby cover to the exact position it was in when you removed it, using the grease pencil marks as your guide. Replace and tighten all six derby cover screws with an Allen socket and a socket wrench.
Adjust Clutch Cable
Re-tighten the clutch cable adjusting nut until the clutch cable reseats in the housing and there is no free play in the clutch lever at all. Loosen the clutch cable adjuster nut 1/2 turn at a time until there is 1/8 inch free play in the clutch lever before you feel tension. Immobilise the clutch cable adjuster nut with an open-end wrench and simultaneously tighten the cable adjuster locknut with a second open-end wrench until the two nuts fit snugly together. Replace the clutch cable adjuster boot.