surfdog420

ya it will fire if i put gas in cyl but wont fire and stay running

i traded a 2007 ltz400 for it

i had the valves checked and their fine,its turns over really good just wont start,its got spark and good compression just wont fire

i have a 06 yfz450 that ran fine a few days ago but now it will only turn over and wont start dose any body have idea on what it could be,ive heared it could be the valves(hoping its not) any help will do