2001 kawasaki kx100 wont start! Help?

[Brian]

I have a 2001 kawasaki kx100!! I have had it for two years and it has run great and had no problems!! It started first kick!! one day i rode it in my back yard and it ran great!! The next day it will not start unless u roll start it and when it starts, the throttle response had a bad delay and it will not idle!! The next day it will not start for nothing!! The spark plug has a spark ,the right mixture of gas, gear lube, and has a very clean air filter!! What is wrong and how do i fix it?? any suggestions will be very helpful!! I just wanna ride!! Thank you so much!!