I have about 6500 miles on my wr400 sm that i built and for the past 2 months i have had it it would start first kick. It always ran amazing and ran great last night, but this morning it wont start. I pulled the spark plug and it looks great, drained the carb and plulled it off to make sure it is working properly and its getting fuel witch it is, so the only thing left is the valves. this is my first Wr, i have always had RMZ's for racing and the vavles needed shimmed alot but they would still start with some effort. do you guys think its the vavles? and if not give me some other ideas to check.