Last weekend both mine and my buddies YZ450's started cutting out/sputtering off the jumps at about the same time of day at Lakewood. This was the first warm Colorado day (79 degrees), and both had major pressure relief (hissing)when the gas caps were loosened. Is there a known problem with the gas caps? My thinking is they are running lean with reduced gas flow, but not sure why it primarily happens over jumps. Both are jetted and have run great to this point (in cooler weather). Never had to re-jet for temperature variation in Colorado before. Any suggestions?