Front Fork


The hydraulic fork is comprised of two sets of telescoping tubes that work against springs, with an oil filled (hydraulic) dampening mechanism to control the action. The unit is engineered to give long service with a minimum of repair. Oil change is not necessary on 1970-72 models unless oil has been contaminated or leakage has occurred. 1973 and later models require oil change initially at 500 miles and thereafter at 5000 mile intervals.

To drain fork sides, remove fork tube cap as described in "DISASSEMBLING FRONT FORK." Remove drain plug (29, Figure 2-31 or 15, Figure 2-36) from lower end of fork slider. Loosen tube end bolt (12, Figure 2-31 or 6, Figure 2-36) several turns. With a screwdriver move shock absorber up and down to loosen any sediment in bottom of fork slider, so oil will run free from drain.

After each fork side is drained and drain plugs have been installed, forks can be refilled by using an improvised filler can.


1. To make a filler can, see Figure 2-32 and proceed as follows. Drill a dozen 1/4 in. holes in the bottom of a one quart tin can (2), near the outside edge. Then, shape the bottom of the can with a light hammer so that it is dished upward to assure complete draining of oil through the ^\>les.

Select a tin funnel (3) with the funnel mouth about the same size as the bottom of can (2). Swage and shape the funnel spout, so that a piece of 1/4 in. metal tubing (4), about 2 in. long (a piece of fuel line is suitable), can be soldered into it. Solder (3) into the bottom of (2). Improvise and attach bail (1) to the filler can.

3. Make plug (7) from a rubber bottle stopper purchased from a drug store. Rubber stopper should be 1 in to 1 -3/8 in. long, and its largest diameter about 5/8 in.

4. Hold rubber stopper in vise and drill a 3/32 in. hole lengthwise through the center. Then enlarge the hole with a 1/4 in. drill. After hole is drilled in the stopper, insert a 1 /4 in. rod (6) through the hole and grind the stopper to a 5/8 in. diameter at the large end, and slightly under 1/2 in. diameter at the small end, straight taper between ends to form the plug.

5. Slightly flare one end of a piece of 1/4 in. tubing (6), about 2 in. long, and insert into plug (7). Make an adapter (8) from an old fork tube cap. Break three stake locks securing breather valve and remove valve from cap. Drill a 1/2 in. hole through cap and plug the vent hole. Assemble adapter (8) to top of fork and insert rubber plug (7) into the adapter hole. Attach filler can to stopper with transparent flexible tubing (5) about 2 feet long.


Suspend filler can above motorcycle so that when improvised fork tube cap is assembled in fork filler opening there will be ample slack in flexible tubing becoming taut (see Figure 2-33).

Pour correct amount of fork oil into can. The difference in the amount of oil required between a (DRY) and a (WET) fork is due to oil cling. Do not use more oil than recommended because the excess oil will cause leakage from the top of the fork tubes.


Fork Oil



1972 and Earlier

5-1/2 oz.

6-1/2 oz.

Harley-Davidson Type B

1973 and Later

5 oz.

6 oz.

Harley-Davidson Type B

Work the fork up and down. Air escaping through oil in filler can as fork is pushed downward will cause the oil to bubble violently, but because the bottom of the filler can serves as a baffle, no oil will be lost. As the fork moves up. oil will be sucked into the fork side Usually working fork up and down 3 or 4 times is sufficient to empty filler can. After filler can appears to be empty, it is good practice to allow a few seconds for can to completely drain into hose, then work fork once more. This assures getting all oil into the fork side

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