I recently purchased a 97 ZX7. When i bought it, the weather was relatively warm and now its generally cold (i live in saint louis). So it warmed up this weekend and i decided to start it up and maybe go for a quick ride. I had charged the battery up and kept it inside as i knew i was going to be doing more work than riding. I also had drained the gas tank and turned off the fuel line. When i tried to start it, the bike was having none of it. Long story short, i figured it was something to do with the spark plugs. I pulled them today, and they were carbon fouled. So i cleaned them, put them back in, and the bike fired right up first time. I know that this is caused by the plugs usually being too cold, or the mixture being too rich. I guess my question is, could someone explain this a little better, and is this a problem i should keep expecting as long as i dont get new plugs, or is it being caused by the radical shift in temperature (20s to 50s) and me not starting it regularly. Also i will be going back to school in a few weeks, and obviously wont be riding it again for a while.