I was riding one time, the fuel ran out and I reached down to turn on the reserve. When I did this I accidentally tripped the choke, which would not have ordinarily been much of a problem except at that same time there was an 18 wheeler passing me on the left. I lost power but I didn't know why. He was signaling that he wanted to turn right at the next turn. He slowed down to let me get ahead, which I would have very much liked to do but my bike wasn't cooperating because the choke was on. He slowed down more to let me know that he wanted me to go ahead. Eventually we came to a complete stop and I was able to wave him on.