My plan originally wasn't to. Yesterday I bought 20 washers at 30mm O.D. by 2mm thick to add some preload to the standard springs. I had to do something 'cause for the three years I've been riding the bike the forks had been bottoming out all the time. With me on the bike the sag was about 70mm and suspension sag should be about one third the travel, the GS has 120mm of fork travel so it should be between 30-40mm sag. I was going to take the handlebars off to access the fork caps and just add the washers with the bike mostly still together. It is a fair bit of work taking the side fairings, the brakes, the front wheel, mudgaurd and fork brace off to get the forks off.
After buying the 'preload' washers yesterday I sat down with a beer and watched a few vids to build momentum up to todays efforts.(I wasted all of Sunday arvo watching Allen Millyard vids ;) ) I came across this Dave Moss Tuning vid (https://www.youtube.com/watch?v=UoIQNcxqaSA) where he starts off showing the stiction in the fork he is working on, then changes the oil, then greases the seal without pulling the fork apart and shows how the stiction is gone. How easy it was for him to put the fork cap back on sold me on the idea of doing what Dave did.
So today with a bunch of stuff removed from the bike I undid the top triple tree clamps and loosened the fork caps then started with the right fork leg, Since the late eighties when i started riding bikes the right fork has always had a cable tie on it to let me know what's happening with the suspension and that came off first. I cleaned the stanchion with some wd40 and a rag and sanded down the high nicks with some slightly used 400 grit sandpaper. Once everything was smooth I gave the stanchion a clean again and removed the dust seal and protector to have access to the fork seal. I used a 0.01mm feeler gauge to clean the seal then did as Dave did, smeared a thin line of high temp grease around the stanchion just above the seal and gave the fork a couple of light bounces to make a concentrated thin line of grease then a couple of hard full pushes to have the seal take up the grease. To quote Mt Allen Millyard "I was well chuffed with that." No grease left on the stanchion at all.
After all that it was time to for me to increase the preload on the springs. With the fork out of the bike all the work is so much easier. I took the cap off, removed the spacer and dropped in 5 washers. It was that easy putting the fork cap back on compared to doing it on the bike I stopped before I had screwed the cap halfway on, undid it and added another couple of washers. With the struggle I had getting the fork cap back when it was on the bike I thought 5 washers would make it way too hard to fit the cap. Seven washers ended up being pretty bloody close to what I needed.
After doing all the above on the left fork I bolted all the bits back on the bike, bounced the front end down a few times to have the spacer in the right fork leg set then checked the new sag when I was sat on the bike.
A repeatable 37mm. So glad i didn't have to pull a bunch of stuff off again to to fine tune it.
My first ride on the bike with the new preload was a sedate one. Pulling the caliper off the bike let me see that the pads were nonometers from being just the metal backing... On that sedate ride the forks didn't compress more than 89mm. I'll fit the new pads tomorrow and put a couplr of tanks of fuel through the bike to see how the changes do stack up. First impressions do suggest there is no need for new sprinngs - just set the preload properly,
Good call on the stiction fix; it should help preserve the fork seals too.
I was shocked at the amount of pre-load the stock springs have from the factory. It makes for some nervous moments
trying to get the caps re-installed without cross-threading.
I switched to the Progressive springs, which only need 0.5-0.75" of pre-load--so a lot less stressful getting those caps on, but I hate
that part of the job on any bike. :)
After riding nearly 300 km's today I can confidently say there is nothing wrong with the springs Suzuki fit to the GS, they just need some more preload. With some really hard braking to bed in the new pads the forks max compression was 105mm. It seems reasonable to go back to 10wt in the forks now...
So glad i spent $4 on washers rather than $100 on new springs.
I have done 2100 km with the extra preload and the forks haven't bottomed out once. The most the sliders have travelled is 110mm. The ride is so much better I wish I had added the preload when I bought the bike 3 years ago. It did take a little bit of time to get used to but I'm happy now.