Here's the story: 14hp FCV420 Kawasaki (single cylinder). Was running fine. Started easily. Then a hour or so later - no start. There's a spark. Fuel delivery doesn't seem to be an issue (breifly emptied the fuel bowl on the carb). Feels like the unit has good compression. After a few pulls on choke - the unit backfires real bad (but doesn't start). Checked the valves - looked good (didn't have a gap gauge though). Took the flywheel off to see if the key had sheared - it was fine too. I was thinking that this is a valve or timing issue - but can't find anything wrong. The last piece of info - it was cold and on/off rain for most of the day.... the unit sat in the trailer for about an hour in this weather before the crew tried to start it.... weather has never been an issue before with this unit. It has always started in the rain and in cold weather. But, I was thinking may the rain has something to do with it )along there is a good spark) Anyone have any other suggestions?