I have three:
The first one, which didn't strand me but that could have been a real problem. I had an XS400 and I'd welded on O2 bungs so I could tune it. While on a ride up highway 6 toward Golden, one of those plugs came loose and fell out. The bike was obnoxiously loud. Fortunately, the plug was far enough away from the head and pointed toward the front of the bike, that it didn't overheat an exhaust valve or bake my leg. I was able to ride home without incident. A guy did stop when he saw me beside the road and offer to put the bike in his van and take me home. I thanked him for his offer and graciously declined.
The second one, which stopped me dead in my tracks, was a punctured rear tube on my Enfield. I was on the first leg of a 3-day, 900 mile ride. I didn't have the tools to repair the tube and was about 25 miles up a canyon without any cell service. The bike wasn't rideable and I was royally hosed. I ended up hitchhiking some 20-odd-miles. A 19-year-old girl with her dog in the back, pulled over and gave me a ride out of the canyon. When I had cell service, I called Fateddy for help. He picked me up, drove me out to the bike and we attempted to repair the tube. Sadly, the tire was too tight a fit and we were unable to spoon it back on. We ended up pulling the rear wheel and rushing it into town to see if someone could fix it. It was nearly 5PM and most of the local shops were closing. I happened to call a Harley dealership and they did have a tube in stock that would fit. They installed the tube and sent us on our way. It was a major pain in the ass, took 7 hours of time and delayed me enough that I ended up riding through the night, arriving at the first day destination at 5AM.
The third, which I fixed without problem, was lost nuts on the exhaust manifold on the Seca II. I was on a mountain road, 30 miles into Utah from the Colorado border and there wasn't anyone for miles. I noticed that the bike was more noisy than usual; I even commented on it to myself. Finally, the noise got really loud and I knew something was wrong. I pulled off to the side of the road and found the manifold nuts missing on the first cylinder. I checked the other cylinders and they were loose too. This was my fault. I'd recently installed new gaskets and torqued to spec but didn't retorque after a heat cycle. I knew better but I didn't. This could have stopped me dead in my tracks but I had the right size nuts in my spare hardware bag and was able to get back on the road without issue. I checked the tightness of all the nuts at every other stop and hotel for the rest of the ride.
