HAve a problem with my 03 wr 450.. It doesen`t run smooth unless I have over 50% throttle or riding uphill or high speed. Feels like it fails to ignite every 5-10 sec.. I have a high comp piston and new jetts.. The spark plugg have a nice milkchocolate color when I ride it hard, but it gets very dark and seems it gets to much gas when I keep to the speedlimits.. Where is the problem?