Classic Motorcycle Build

Sportster Primary Chain (Remove and Install)

Removing the primary chain from your Ironhead Sportster requires several specialty tools. All can be bought and most can be fabricated. A service manual is always helpful.

Sportster primary chain cover removed

First step is to remove your hand clutch lever and primary cover. Note the different length bolts holding the cover.

The clutch assembly comes out next. Refer to the clutch remove and install page.

Remove the three bolts from the primary chain adjusting brace. This will leave the adjuster loose behind the chain.

Sprocket Locking Link Tool

A tool is needed to keep the two sprockets from turning while you remove the hub nut. You can either borrow one, buy one, or fabricate one. The tool fits in between the clutch hub and the large nut. After the tool is in place, bend back the tabs of the lock washer so you can get to the hub nut.

The picture below shows the sprocket locking link tool holding the clutch basket and compensating sprocket.

Ironhead Sportster sprocket linking tool

A 1-1/2" socket is needed to remove the large nut. Some bike shops use an impact gun on this nut, instead of using a locking tool. Either method works.

Sportster sprocket linking tool

To remove the compensating sprocket shaft nut (front pulley) another specialty tool is needed. One can be made, but they're pretty cheap to buy.

Sportster sprocket shaft tool

Order of compensating sprocket shaft assembly is sprocket shaft nut, sprocket spring, sliding cam sleeve, sliding cam, and sprocket shaft extension.

The compensating sprocket shaft nut, clutch shell, and primary chain will come out together.


Inspect all parts for wear. Clean and blow dry with compressed air. The clutch shell should be inspected for any wear or damage. Inspect for worn sprocket teeth, worn or loose keys, or damaged ring gear teeth.

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Ironhead Sportster clutches from 1970-on were wet. They run in an oil bath and generally do not wear out. Unless your bike was abused (raced), your Sportster primary chain may outlive you.

Sportster primary chain

Inspect the primary chain adjuster plastic shoe. If it has deep grooves (like the one in the picture below) or it's worn (less than 1/4" of original thickness) replace it.

Ironhead Sportster primary chain adjuster
Ironhead Sportster left engine case

Install Primary Chain

The hub nut and lock washer (use a new one) go back over the clutch gear splines. Install the lock plate tool to tighten the sprocket shaft nut. The clutch hub gets tightened with a socket, and needs to be tightened to at least 150 foot/pounds. To do this, it's OK to strike the socket handle with a soft mallet.

After tightening, bend the ears up on the new lock washer to prevent it from loosening.

sportster primary chain

Primary Chain Adjustment

Primary chains don't really wear, but if it's too tight it will stretch. The chain tensioner should have 3/8" to 1/2" movement.

Re-install clutch assembly. Refer to clutch remove and install page.

Reinstall primary cover with new gasket and sealant. Remember there are different size bolts.

After your bike is together and running, listen to the left side of the motor. If you hear a whining noise coming from primary, the chain is too tight. If it's too loose you can hear a rattle. It's better that the chain is a little loose than a little tight.

Clutch Adjustment

To adjust the clutch, unscrew the large assess plug. (using the side of a wrench is better than using too-small a screwdriver). Loosen the locknut. With a flat-blade screwdriver take up the free play on the adjusting screw, then back off a 1/4 to 1/2 turn. Basically you are turning it in until you feel pressure, then backing it out some. The backing off is to make sure the clutch is fully engaged. Tighten the locknut without moving the adjusting screw. Make sure there is an o-ring on the back of the assess plug before re-installing (to prevent a possible oil leak).

Read: Ironhead Special Tools