You may need to provide more information, are you getting compression? after you crank it a few times is the plug wet? does the bike try to start, splutter and die?
Assuming your kit is "standard," you have installed it correctly and you are getting fuel into the engine I would suggest playing with the mixture by moving the E clip on the needle.
This has been a fairly common cause of failure to start in kits I have installed/worked on for friends.
If it still doesn't start its time to start searching the threads..