So I wanted to try (... somehow these words seem to always be a prelude to disaster ) ... Anyway, I wanted to try the low octane fuel setting on my '07 640A. Disconnected the famous brown wire, turned the starter and the bike ran like crap: only ran with choke on full, and even then coughing. Reducing choke made it die. Ok, bad idea. Connected the brown wire again, no improvement. The symptoms seem to be a clogged main jet, and a clue is that the bike has been sitting in the garage for a while (yes, I know, I should be getting more ideas about riding and less about playing mechanic ). On the other hand on the last ride (a few weeks ago) there were no problems whatsoever. Coincidence? Did the jet decide to clog right before I had the bright idea to try the low octance setting? Or did I mess something else up? I haven't opened the carb yet, and honestly would like to avoid it if the problem is elsewhere.