A little bit ago while riding, I heard a loud clang in my fork and the front end immediately went wobbly and the bike dove heavily under breaking. It was definitely an unnerving surprise, considering I also had a recent front tire puncture flat, but I made it back to the shop without incident. I had a chance to drop the forks this evening and this is what I found.
Upon removing the fork cap on both sides, I noticed the spring capture retainer at the top of the spring stack on the inner fork assembly in my left fork (clutch/ABS sensor side) had come undone. The semicircle retainer clips were free floating and the piston was all the way depressed down in the leg. I suspect this is because of an oversight by whoever had them apart last. I know those clips can be difficult to get seated fully. The assembly was undone but nothing was visibly damaged on the black cap, retainer pieces, spring retainer cap washer?, or grove in the piston shaft that the retainers seat in. These are a set of ebay used replacements for mine whose stanchions had become pitted and were destroying fork seals. These were sold as operational and taken off a working bike, and I've put about 1000 miles on them in heavy duty use around the SF Bay Area. They worked quite well for a while, but were definitely not right after that loud clang.
I checked everything for abnormal wear and nothing was binding or sticking. I installed my Works progressive springs from a previous set of forks (with about 5k miles), and everything seemed normal. However, when they were fully assembled with proper amounts of oil according to the factory manual, the left side has NO rebound damping. There are no visible oil leaks anywhere outside the fork and after removing the dust cap and watching the fork seal during a few strokes, there are no leaks.
I have done several successful fork jobs on the K1100RS forks, I've owned 2 of them. However, like I said, it's the first time I've been into these and the left side was not functional when removed. I do not recall noticing a difference in rebound damping in previous fork jobs, though I don't recall specifically testing for that. If both fork legs are supposed to have equal rebound and compression damping, they most definitely do not and I suspect the left fork leg cartridge is to blame? It's the only complex assembly in these forks from what I can tell. My guess is that when the spring assembly came un-retained inside the fork, it blew out some sort of seal in the valve/piston assembly.
Any help confirming some of these questions would be a great help.
