Motorcycle Repair: WANT CRANK, yamaha r6 2002, cam shaft

Question
I PUT A NEW HEAD GASKET ON MY YAMAHA R6 2002 PUT EVERY BACK TOGETHER AND FIRED IT PUT UP AND ALL IT DOES IS TURN OVER AND BACKS FIRE THE ENGINE WILL NOT CRANK WHERE COULD I HAVE GONE WRONG THE SPARK PLUGS WERE OK BEFORE I REMOVED THEM COULD THE CRAMS HAVE SOMETHING TO DO WITH THIS I HAD TO REMOVED THEM TO GET TO THE HEAD BOLTS IS THERE A DIFFRENTS IN THE INTAKE CAM AND EXHAUST CAM SHAFT THEY LOOK PRETTY MUCH THE SAME

Answer
HI TERRY

PERFORM A COMPRESSION CHECK TO KNOW IF THE CAMS ARE OUT OF TIME AND HOLDING OPEN A VALVE(S) IF THERE IS NO COMPRESSION THEN THIS IS LIKELY THE WHATS HAPPENING HOPEFULLY THEY WERE INSTALLED PROPERLY AND VALVES ARE NOT BENT

RESPECTFULLY
MARK SHIVELY