One day I came out to find someone had knocked over my baby. Upon closer inspection I noticed a fluid leaking all over the brake calipers and found that a fork seal was leaking. Here is my description of how I fixed them and what not to do.
!!!PRIORITY!!! Protect the stanchion tubes. If there are any pits, scratches, dings, etc in the travel area you'll wind up replacing the seals until you go mad, like I did, with no luck. This was the painful lesson learned. I didn't even notice the small pits on mine, replaced the seals using every manufacturer I could find just to have them start leaking again two miles down the road.
The first time I attempted this procedure the exhaust off so it was really easy to lift the front up evenly and slide some stands in under the frame to secure it. Later, with the exhaust back on its tough to get a jack under there evenly so I used my rear stand first to keep it even and then raised the bike with the jack and then removed the read stand. Two people needed! Make sure to remove the front fender, loosen the top fork plug the fork clamp bolts and the axle pinch bolts a bit while its down to make them easier to remove when its up.
Once up (I long for a center stand for this work) loosen the retaining bolts. There is the main one at the top (14mm), two in the middle (12mm) and I even unscrewed the air pressure screws. Use an allen wrench to separate the anti-dive unit from the fork. It splits in 2 on the front side and keeps the fluid inside which is nice if you want to keep oil from draining all over. Not that I would know.
The calipers are held on with two 14mm bolts. Tie them to the frame to take the weight off. There are four pinch bolts (14mm) on the bottom of the forks that once removed will allow the front wheel to be easily set aside without even messing with the axle. Set the wheel against the engine. All 4 of my bolts were stripped and so I eventually ordered all new nuts and bolts and added some lock-tight to the lag bolts. Undo the nuts holding the forks in and pull them down while twisting. This took a bit of effort the first go-round as I think the rubber on the air pressure system was grabbing. Maybe a little lubricant spray would help?
Once both forks are out (If you are changing one you should do them both) You can begin the disassembly stage. Place a rag over the the large top nut and remove it slowly, keeping your face away as it may spring out. This is a 22mm nut I believe. Once that is out set the nut, cap and spring on a paper towel. Drain the fluid from this end.
The next part was a bit tricky and I got a little lucky. There is a bolt on the bottom that holds the two pieces together. I bought a dowel from Lowes, a quarter inch I believe, and shoved it down the top and into the recces that is on the long aluminum rod thing holding everything together. Use a #10 allen and, while holding the dowel from spinning, give the bottom nut a good twist to break it free. If you have a nice grab with the dowel it should unscrew fairly easily. More fork oil will drain from the bottom once the bolt is removed so get ready. Keep an eye on the little brass washer as well.
Now the stanchion and lower forks can be pulled apart for cleaning. Remove the dust protectors. Grab each side and give it a few pops outwards to separate the two. Careful, there are three small washer and a little cap inside with the connecting rod that may fly out when you do this. How do your seals and bushings look? Mine were thrashed!
I set everything on some shop rags and cleaned it all very thoroughly, inside and out with a degreaser. I also took this time to repaint the lower fork legs with a satin black to match the rest.
Everyone says to do these one at a time in case you need to reference the correct way to reassemble them. I have the repair manual which really helps with the correct order. Now I can do it with my eyes closed but the first few times is a bit over whelming due to all the parts. I'll included a scan of that manual pic in the next edit in case you don't have it.
Once cleaned you can reverse the process. After the bottom nut is secure the fork is now whole again. If you have nice smooth stanchions you can just slide the seal down with a touch of fork oil. Another lesson learned - The seals will pop in fairly easily if they are good. I highly suggest using OEM. DO NOT USE the "leak proof" seals from ebay. Another lesson learned. They likely wont fit and you may wind up forcing them on and damaging other parts. Not that I would know about that either. The trick to tapping down the seals evenly (you likely don't have a Suzuki seal tamper) is to use two pieces of PVC plumbing pipe. I found mine at Loews and cut them vertically to fit on the stanchion and then another over it. (see photo below, its the white tool on the right). Layer them so that the outer pipe is longer then the under pipe and then use some clamps to secure is. Use the movement of the shocks to tamp the seals in evenly. Again, they should go in fairly easily with a few good tamps.
Easy right? You'll get it. Once the seal is in and the washer and clamp fit back in, slide down the dust covers. Almost there. This is when I put them back through the triple tree and bolted them down. Not sure if this is the proper procedure but it worked. Fill the shocks with the correct amount of fork oil. I bought 15W on amazon for about $12 a liter. My GS1100E needs 248mL per legs. I used a $1 measuring cup from the dollar store as I doubt I'll use it for cooking again. Some people on you tube compress the forks now to work the fluid in and the air up. I put the spring back in (careful to put the tighter curls on top) and the little spacer and then the cap nut. This takes a little work to get it going but with the forks fully extended its possible.
Bolt everything back on, including that wheel and tighten to spec. Pump your brakes back up. Get some help lowering it and voila, new forks.
Because of the bad stanchions I wound up doing this 4 times and then eventually just bought a set of used forks on Ebay. I popped those in in about an hour and now am leak free. There are more details about this procedure that I omitted for length so feel free to email me with any questions. Good lucking and happy forking!