See also Crankshaft / Flywheel Tools in the Reference section of the Sportsterpedia.

• Sprocket Cover Dowel Hole (Case) Repair
• Engine Case Numbers
• Ironhead Engine Case Identification
• Ironhead Primary/Chain Cover Pics
• Ironhead Gearcase/Cam Cover Pics
• Ironhead Transmission Sprocket Cover Pics
• Catalog of OEM Flywheels
• Sportster Drain Plugs Explained
• Tapping or Installing a Helicoil on a Drain Plug with the Engine in the Frame

1977-2003 Sportster Primary Cover Shifter Shaft Bushing 40520-63:

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These are used in the “pocket” in the center of the primary cover.
1971 XLH, XLCH used the transfer labeled “900” (34960-71).
1972-1976 XLH, XLCH used the transfer labeled “1000” (34960-72).
1977-1980 XLH, XLCH used the transfer labeled “Sportster” (34961-77).
1979-1980 XLS used the transfer labeled “1000” (34962-79).

These models use 1 threaded polished and knurled oil filler hole plug (34742-52A) on the primary cover.
It screws into the hole in the primary cover with no seal. There is a small hole drilled through end to end of the plug.
This allows air to come into the primary replacing what's lost to the crankcase from the transfer valve in the left case half.
There is a mesh filter on the primary side of the plug that is staked into place.
The plug has a slot milled out across the face as a socket for removal/installation and the tool is similar to and fits into the slot.

These years use 2 plugs, polished oil filler hole plug (34742-71) and polished clutch adjustment hole plug (37880-71).
The oil filler plug is not knurled, uses an O-ring (11106) and has the small through-hole with filter mesh for primary air intake.
The clutch adjustment hole plug also uses O-ring (11106), has no through-hole vent and has overlapping slots cut into the face in a “cross” pattern.
This plug was introduced on the primary cover with the redesigned wet clutch models and installs over the clutch adjuster.
It doesn't install flush with the cover.

1977-1985 models use 2 identical hole plugs for the oil filler hole and the clutch adjustment hole.
It's looks the same as the 1971-1976 oil filler hole plug 34742-71 but it has no vent hole.
The primary now breathes from a rubber tube on the top rear of the transmission.
The plug went through a couple revisions but any of these will fit and function on 1977-1985 primary covers.
1977 models used (34742-77)
1978-E1985 models used (34742-77A)
L1984-1985 models used (34742-77B)

Oil Deflector / Separator Bushing Assembly (57-62): (or spring loaded top hat)

Looking at the brass part, you can see how the spring catches on the inward bent tabs. There are also unbent tabs on the brass. ⁵⁾
These, when bent outward just a little, fit into slots on the far side of the steel bushing pressed into cam cover.
Here's how the factory assembled this thing.
They had pre-assembled the brass to the steel before the steel was pressed into the cover.
Then dropped the spring into the cover and pressed the brass/steel assembly into the cover as a unit (and manipulated the spring to sit correctly if needed).
However, it is possible to assemble the unit without removing the steel from the cover. ⁶⁾
You can bend the tangs out without having to remove the steel bush with a screwdriver and a hammer to bend the 2 locating tabs out.
Notes:
The tabs must be bent outward enough that the brass stays keyed to the steel at full spring compression.
You don't want the brass hat to 'unkey' when the generator compresses spring. The brass needs to be able to 'plunge' in and out under the spring pressure once the tags are bent.
If you get too aggressive, you can cause deformations in the brass that allow it to hang up in it's sliding fit to the steel.
These outward bent tangs do 2 things.

• They keep the brass hat and spring captive in the cover upon generator removal.
• More importantly, they key the brass to the steel to prevent the brass from rotating with the generator gear.
  The brass is unable to rotate by the tangs keying into the slots.

Inspection:
Check the operation of the oil separator bushing assembly.
The spring should have free action and be fully extended in the gearcase cover.

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• If you've split the cases and the screen is in good shape, you don't have to take it out. Hit it with some compressed air and see if it needs replacing. ¹²⁾

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The strainer is held in place by this pin. It is staked into place with the two horizontal lines radiating from the it. To remove strainer, you must first remove the pin. Tear the screen from the strainer and place pliers on the pin inside (the now destroyed strainer) and wiggle the pin out. Strainers and strainer gaskets are available for replacement. ¹⁵⁾

• In May of 1981, the MoCo issued a bulletin stating that product and quality improvements have brought about a commonized flywheel taper design.
  

All tapers were communized at 6° and all keyways were standardized. In June of 1981, an update to this bulletin was issued to include part numbers. ^{36) 37)}

• A limited number of E1982 XL engines (782216009-782237017) were assembled without the communized flywheel taper design. ³⁸⁾
  • Notable component changes are included in the chart below.
  • This was a running change in 1340cc and 1000cc engines but both new and old designs were used in production until the old stock parts ran out.
  • Assembly and disassembly was the same for the old and new style flywheels but the torque values did change for the new style assembly.
    However, new and old style components must not be intermixed.

Changes for Sportster 1000 engines include:

New Flywheel - Sprocket Side Gear Side	23916-80 23936-80	'Lazy 8' rear cylinder timing mark and no keyway Single hole oil path.
The old style flywheel has a keyway on the sprocket side (23916-57A) and a compound (2) hole oil path on the gear side (23936-57A).
New Crankpin	23960-80	Oil hole is now 90° to the keyway
Old style crankpin (23960-54) oil hole was 110° to the keyway
New Crankpin Nuts	23901-81	20/1“ thread pattern at 150-185 ft/lbs.
Old style crankpin nuts (23967-54A) were 20/1” threads with 150-175 ft/lbs.
New Sprocket Shaft	24000-80	No keyway
Old style sprocket shaft (24000-75) has a large keyway
New Sprocket Shaft Nut	23902-81	3/4“ x 20 threads at 100-120 ft/lbs.
Old style sprocket shaft nut (8011) has 11/16” x 18 threads at 100-120 ft/lbs.
New Sprocket Shaft Key	Not used
Old style sprocket shaft key (23985-12) has a large woodruff key (3/16“ x 1/2”)
New Gear Shaft	24005-80	One piece construction
Old style gear shaft (24008-75A) is of two piece construction
New Gear Shaft Nut	23902-81	3/4“ x 20 threads at 100-120 ft/lbs.
Old style gear shaft nut (8011) has 11/16” x 18 threads at 100-120 ft/lbs.
New Gear Shaft Key	11218	Small woodruff key (1/8“ x 3/8”)
Old style gear shaft key (11200) has a large woodruff key (3/16“ x 1/2”)
New Crank Key	11218	Small woodruff key (1/8“ x 3/8”)
Old style crank key (23985-18) has a large woodruff key (1/8“ x 1/2”)

• In a letter dated May 9, 1977, an HD interoffice memo was sent regarding an inspection of parts stock roller bearings. Some roller bearing part numbers were found to have incorrect diameters. A new micrometer was purchased to remedy this problem.
• Two of those part numbers are gear shaft (9421) and crank pin front rollers (9150A) for Sportsters.
• In light of this oversight, a listing of part numbers with their correct dims and tolerances was issued as in below:

Used for 57-76 Sportster gear shaft roller bearings	Diameter	Size	Length
9421	.1876“ - 1974”	Standard	.800“ - .796”
9422	.1878“ - 1876”	+ .0002“	.800” - .796“
9423	.1880” - .1878“	+ .0004”	.800“ - .796
9424	.1882” - .1880“	+ .0006”	.800“ - .796”
9425	.1884“ - .1882”	+ .0008“	.800” - .796“
9426	.1886” - .1884“	+ .0010”	.800“ - .796”
Used for 54-85 Sportster and K Model front crankpin roller bearings	Diameter	Size
9150A	.1875“ - .1874”	Standard	.480“
9152A	.1877” - .1976“	+ .0002”	.480“
9154A	.1879” - .1878“	+ .0004”	.480“
9156A	.1881” - .1880“	+ .0006”	.480“
9158A	.1883” - .1882“	+ .0008”	.480“
9160A	.1885” - .1884“	+ .0010”	.480“
9161	.1873” - .1872“	- .0002”	.480“