yz426f wont start
 

so i have a 2002 yz426f dirt bike and i bought it from a guy to see if i could clean it up and make it run better, it took forever to start it when i bought it and it runs great when u get it started, ive only been able to start it one other time since then so i decided to clean the carb. it was very dirty but i cleaned it really well and pretty much rebuilt the whole carb lol, and then put it back together and still no luck starting it, then i decided to replace the spark plug since the old one was burnt and i also checked the valve clearences too and they were in spec. after all that i still cant get it to start, its getting spark, and the carbs clean and the valves arent too tight either, oh and i also put fresh gas in it.
Any ideas why it wont start??? i have no clue.:huh: