I rode my '98 WR 400 last Thurs., and I went out to the garage today to try and start it up. I could kick through all 4 strokes now, and before I had to use the decompression lever to get past top dead center. It would only sputter for maybe 1/2 a second and wouldn't fire. Could the valves be out of adjustment or could it be something worse? I'm wondering why this happened when it performed flawlessly on Thurs.