2010 C14, 35K miles, original owner. Home base is about 20 feet above sea level. Last summer, on a day trip on the North Cascades Highway between the coast and Winthrop, WA. and back home, I noticed my clutch wasn't disengaging on command near the summit on the return trip. Altitude was 4000-5000 feet, temp in the mid 80's. I pulled into a trailhead/rest stop to investigate. Noticed a trace of fluid weeping between the clutch master and its cover. Removed the cover to see if anything was obviously wrong and there wasn't - gasket looked perfect. Reinstalled the cover as tightly as I dared, wrapped a rag around the master in case the weep turned into something worse that might remove paint. Clutch seemed to be better... good enough to make pulling out pretty normal. At home, I checked it over again and nothing out of the ordinary. Cleaned up the master cylinder exterior and no trace of fluid w eeping has occurred since.
About a month later, took another day trip up to Mt. Baker with a friend. Near the summit, we had to stop for a flagger. Lo and behold, no clutch disengagement. Altitude was similar to the previous occurrence, but it was about 10 degrees cooler. Getting restarted on a steep uphill grade with no clutch was a bit of a challenge for the bike as well as myself. Once we dropped back down to lower elevation, normal clutch action returned.
Talking to a local dealership's service department and they suggested air in the system could be the cause. Air expanding at altitude seemed to make sense. I ordered a new gasket for the master (just to be sure it wasn't part of the problem) and bled the system, replacing all the fluid.
I didn't have any high altitude rides until last month when I took a one week trip with a couple of friends. Over the course of things, the clutch failed to disengage on many occasions. The freaky thing was one rest stop we made was at 7200 feet (and 56 degrees). The clutch worked flawlessly this time.
Ideas?
