Hello. I have a 2007 yz450f. I changed the piston, rings, and timing chain out today. Now my bike won't fire. Everything on the bike ran good before I tore it apart. I don't know why my bike won't fire. I checked to see if the plug was sparking, and it was. I tore the cams out and changed them around like 5 times because It is SO HARD TO FIND T.D.C.. My flywheel has like a " |-| | " on it. Looks like an " H " sideways and then a mark up and down. What I also did was took the plug out and stook my 1/4" extension on top of the piston and when the extension was at the highest point (piston at the highest point) The sideways H was turned clockwise almost out of view. Please help me find T.D.C.. Also, why wouldn't it be firing? AGAIN, MY BIKE RAN FINE BEFORE I TORE IT APART, JUST PUTTING A NEW PISTON IN FOR NEXT YEAR.