90 Sportster Leaky Fork Seal…

Getting close to getting the 90 Sportster back on the road. While it is on the lift being put back together I noticed a leak in one of the fork seals. When I put this bike together originally I did not mess with the front fork. Who knows how long the fluid has been in there or how old the fork seals are, so the forks are getting rebuilt while she is up on the lift.

Picked up a 39mm fork seal kit from JP Cycles. This kit is inexpensive (about $20) and includes everything necessary to rebuild a set of 39mm front forks: seals, dust covers, o-rings, bolts, copper washers, and clips.

First thing to do is to remove the front fender, front brakes, and front wheel. Loosen the pinch bolts and carefully slide the tubes out of the tree. Then disassemble the forks removing all the seals and dust covers. The bottom bolt is a 6mm hex, loosen this bolt before removing the top cap keeps tension on the spring and helps keep the internals from spinning when you loosen the bolt. After getting the forks disassembled and cleaned up I put them all back together with the new seals, clips, and dust covers from the fork seal kit.

When I was pulling apart one of the forks the clip which holds the seal in was missing. Might be what contributed to the leaking.

Yet another video in the blazing heat. I have to turn the fans off in the garage when I am recording a video, otherwise the fan noise is all you hear. I was drenched in sweat by the end of it and it did not even take that long. I might need to rethink some kind of cooling system in the garage. It has just been crazy hot and humid lately. It will cool down soon I hope then I’ll forget all about how hot it is in there. I might start saving up for a mini-split system in there.

The Motion Pro 39mm Fork Seal Driver is handy to have to install the seals and dust covers but there are other methods which work just as well.

Once the forks were back together I filled each of them with 10.2 Ounces of fork oil per the repair manual.
Front Forks Reassembled on the 1990 Sportster
After getting the forks, front wheel, fender, and front brakes put back together I buttoned up the rest of the bike. She is ready to be taken out for a ride…

Build. Tinker. Ride.

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