i have a cbr 600 f 98 and ive left it for about a week and now it dont start. It turns over ok but wont fire up instead it backfires anybody help me out ????

 

sounds like it's flooded
Pull a plug and examine. Is it black?

This happened to me a while ago. Someone "tipped" over my bike in the garage (where I have it stored). The fuel was also left on by some a$$. It took a few hours to get it fired up (I was backfiring just like you)

Pull all the plugs and dry them. Try to start the bike a few times with the plugs out. Re-install plugs and try firing again. It will eventually start. Try starting without the choke first.

If it doesnt work, let me know. You may not be getting spark.

 

just another note : Keep a battery charger nearby. The constant cranking may kill it