wont start now

[wpbfrider_11]

Had my bike for a couple years now bought it brand new out of the show room and rode it everywhere its a 2009 got it with 0 miles now has over 17k I have always done the maintenance myself.

Well one day I was riding and the spark plug shot out of the engine but luckily the threads were still there so I put it back in and kept riding then it happened again about a 1000 miles later but the treads were shot so I parked it till I got the time to rethread it so I took the head off did a new head gasket too wasn't to hard I put it back together and triedstarting it up it sputtered a little bit and would fire but die instantly. I checked for spark have good spark. Cleaned the carb so should be getting fuel. Tried starting it again and same results so I checked the timing and I had the cam timing backwards so I changed it. By backwards I mean when the marks are supposed to be lined up they were but the cam was upside down I think the technical term would be 180° off. But after changing it I still get a sputter like it is trying to fire but now it doesn't even fire.

I don't know if there is something I'm missing or if the engine is just at the end of its life