1993 K1100RS, Leaking fluid from top of the dust cap on left front fork. Removed forks and am thinking of swapping out the fork seals on both of them. How do I go about this?

Before you remove the fork loosen the top triple clamp on the fork you want to remove. Now loosen the top cap of the fork. Loosen the bottom triple clamp and slide the fork out of the bike. Remove the top cap of the fork.There is spring pressure pushing against the cap, but if the fork is not being compressed it not difficult to take off or to put back on. When it is removed pour the oil in to a container and reinstall the cap. In stall the cap all the way but you don't have to tighten it.
Slide the dust cap up and off of the fork without scratching any of the chrome. Now remove the "C" clip or spring that was under the dust seal and place with the dust seal.Flip the fork upside down to access the allen head bolt in the bottom of the fork. Using an impact driver break this loose. Once loose remove the top cap and spring from inside. Now remove the the bottom bolt. Holding both tubes of the fork compress and snap apart quickly. This might take a few times but the should come apart rather easily.

To replace the front fork oil first support the motorcycle so the front end is off the floor and the forks are fully extended. Remember that the FLSTC and FLSTF models have a preloaded fork spring and that the fork tube plug is under spring pressure.Then you remove the fork tube caps. And then you drain the fork oil. ON FXSTD models, your remove the drain screws and washers from each fork and drain the fork oil this way. ON ALL MODELS EXCEPT the FXSTD, remove and discard the drain screws and washers from each fork and drain the fork oil and then you install new drain screws and washers. ON FXSTD models, apply LOCTITE THREADLOCKER 243 (blue) to the drain screws and tighten them to 12-18 inlbs (1.4-2.0 Nm). ON ALL MODELS EXCEPT FXSTD, tighten the drain screws to 52-78 in-lbs (5.9-8.9 Nm).THEN fill the fork with Harley-Davidson TYPE E FORK OIL (Part No. HD-99884-80).Either by installing oz or cc's of fluid if the forks were left in the frame or by measuring the amount of oil in the tubes in inches or mm if the forks were removed from the frame and disassembled. In the latter case the oil level is measured from the top of the fork tube with the spring removed and the fork fully compressed.

MODELs FLSTC, FLSTN use 13.4 OZ 395 cc4.41 inches 112.0 mm
MODEL FLSTF uses 13.4 OZ 397 cc5.04 inches128.0 mm
MODELs FXST, FXSTB, FXSTC use 12.5 OZ370 cc 6.69 inches170.0 mm
MODEL FXSTD uses 11.6 OZ343 cc 7.48 inches190.0 mm

FINALLY tighten the fork tube caps to 40-60 ft-lbs (54.2-81.3 Nm).

cOULD LEAKING FORK SEALS CAUSE FRONT BRAKES TO FOUL? -- YES
You shuld get a manual, you must check the surface of the fork, if there are scratches, you will destroy a new seal.

Assuming you have slackened off the fork top nut before removing the fork from the bike,and you have removed the screw in the fork lower, this secures the damper into the fork, next you will have removed the dust cover and seal retaining clip from the top of the leg, undo the fork top nut completly and remove the spring noteing which end of the spring is at the top, for replacment purposes.
Next fasten the lower of the fork into a vice on the flat ( not tubular surface of the fork leg) push the stancion all the way down to the bottom of the leg, then pull up sharply, repeating this in/out action to hammer out the seal from the leg until the seal/ bushes/ and washer have come out, this mat take some quick action movments to remove or separate the leg, forks which have not been appart in some time may need some heat on the fork seal. ARea of the lower leg

Remove fork spring, prise up dust seal, you will then see a clip holding in the main seal, remove this clip, with the spring removed you will then use the fork stancion to remove the seal, holding the fork lower in one hand and the stancion in the other push down on the stancion untill it stops then pull it up sharply, and repeate this hammer action until the fork is sepparated and the seal will then be removed

leaking at the seals on the slider? Or at the top above the tree? Either way, the fork will have to be taken apart and new seals installed. Leaking at the top, need internal build.

You need prop the bike up on front and rear stands. The fron stand needs to be the type that holds the bike up by the headtube. Remove brake calipers, front wheel, fender. Then loosen the upper and lower triple clamps. Loosen the clip ons. But before loosening the lower triple, loosen the fork tube top caps.

Drop out the legs. take off the top caps, pour out the oild, and compress the spring. I'd use a fork compressor, race tech makes a nice one. Loosen the top cap from the damping rod. Remove the top cap then pump out the rest of the oil from the damper.

Next, remove the outer dust seal. Remove circlip. Then you need to just extend the fork several times quickly to "bang" out the oil seal and bushings.

The outer bushings, if they look good, need to be gently pryed off using a thin flat head screw driver in the **** of the bushing. Same with the inner bushing. Now the oil seal, metal washer and circlip all come out together. Remember the order.

Lube up the new seals with fresh oil. put back on the fork lowers in the same order they were taken off. Replace bushings at the same time if there's any brass showing. I usually do it any way since the seals seem to go at the same rate as the bushings for me.

Once back together, seat the seals. There's a tool for this, but I usually **** the old oil seal so I can get it on the lower fork tube between the new oil seal and new dust seal. and I quickly compress (bang) the fork a few times until the groove on the upper leg is showing so the circlip will lock back on. Probably not recommended but I haven't ruined a dust seal in about 20 years now.

Fill fork with proper oil viscosity and volume (don't remember how much or weight for zx7s). cycle the damper about 20 times to make sure they're full of oil too. insert spring, re-compress, lock on top cap to damping rod. screw on top cap. reassemble fork on bike. Remember to torque the top cap with the top triple clamp loose otherwise the caps can bind.

Your front fork seal are bad and need to be replaced.
When you loose fork oil, your loosing suspension dampening and only riding on the springs.(POGO)

Replace both front fork seals and dust caps, and put same amount of fork fluid in both forks.

I bought my seals and caps for $30 on ebay, and then took my forks off my bike and took them to a shop and they charged me $75 to do the job.

You can take them the whole bike and they will charge $100 - $150 including parts to do the job.

forks need to be removed,and disasemble,and cleaned,new fork seals,reasembleb fit new seals, refit damping cartridge,fill fork with 5w fork oil upto 120mm from top,refit spring, refit fork cap

What is your question?