non start kawasaki kle500a1?

I have a kle500a1 that wont start . script as follows
1. had a sticking choke . freed this up with wd40
2. used some carb cleaner as well on the carb body and bell mouths . coughed and spluttered but cleared after a few seconds
3. stopped the engine . cleaned inside carbs with carb cleaner
4. now wont start . it has back fired a few times but now nothing not even trying
5. taken carbs off and cleaned and blown out . new spark plugs . checked timing all ok and float levels . good spark . turns over well .but still nothing
where should i go ne