Sportster Primary Chain (Remove and Install)
Article and Pictures by Mark Trotta
Removing the primary chain from an Ironhead Sportster requires several specialty tools. All can be bought, but most can be fabricated.
For a full article on Ironhead Special Tools click here.
Primary Chain Removal
First, remove the hand clutch lever. Next, drain oil from the primary cover.
On 1977-up Sportster models, loosen the chain tensioner from underneath the primary cover.
Primary Cover Removal
Note that their are different length bolts holding the cover.
I use a piece of cardboard to keep the bolts in order.
On pre-1977 models, remove the bolts from the primary chain adjusting bracket. This will leave the adjuster loose behind the chain.
Ironhead Clutch Removal
The clutch assembly comes out next. For a step by step how-to, refer to the Remove And Install Clutch page.
Sprocket Locking Link Tool
There is a special tool to keep the two sprockets from turning while you remove the large hub nut. Another method is to use an impact gun, instead of the locking tool. Either method works.
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 above shows the sprocket locking link tool holding the clutch basket and compensating sprocket.
NOTE: A 1-1/2" socket is needed to remove the large nut.
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.
The compensating sprocket shaft nut, clutch shell, and primary chain are removed together.
Compensating sprocket shaft assembly:
Sprocket shaft nut, sprocket spring, sliding cam sleeve, sliding cam, and sprocket shaft extension.
Inspect All Parts
The primary chain runs in an oil bath and generally does not wear out. Unless your bike was abused or raced, a Sportster primary chain may outlive you.
Inspect the 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.
Inspect all other parts for wear. While it's visible, inspect the clutch shell for any wear or damage. Look for worn sprocket teeth or damaged ring gear teeth.
Install Primary Chain
The hub nut and lock washer go back over the clutch gear splines. The lock washer should be replaced with a new one.
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.
Primary Chain Tensioner
There are at least three different primary chain tensioners for Ironheads:
- 1957 to 1976 XL and XLH: 39975-52B
- 1958 to 1969 XLCH: 39975-54A
- 1977 to 1980 ("old style") - 39975-75
- 1980 to 1985 ("new style") - 39975-80
Primary Chain Adjustment
Whichever chain tensioner you have, the chain should have 3/8" to 1/2" movement at it's tightest spot. To re-install clutch assembly, refer to clutch remove and install page.
Reinstall primary cover with new gasket. Gasket sealant is optional.
Note that there is an early and late primary cover gasket. If you bought a James Engine Gasket kit, it comes with both.
Shop: Ironhead Primary Gasket (1967-1976)
Shop: Ironhead Primary Gasket (1977-1985)
After the primary cover is back on, the rear foot brake lever and foot peg can be re-installed. Then refill primary oil.
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).
After the 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 the chain is too tight it will stretch.
If the primary chain is too loose, you may hear a rattle. It's better that the chain is a little loose than a little tight.
Hardware Dress-Up Kit
Drag Specialties offers a side cover hardware kit For 1977 through 1985 Sportsters. Includes Allen-head bolts for cam cover, primary cover, and sprocket cover.
Shop: Side Cover Hardware Kit For Sportster 1977-1985