I just shimmed the valves on my 2008 YZ450F for the first time. The bike started and ran good after finishing but it was backfiring bad and seems to be running hot. I removed the 45 pilot and installed a 48 from the jd jet kit with the screw open 2 turns. Still backfiring very pronounced on decelleration. I removed the spark arrestor and found what appeared to be fiberglass packing. After running without spark arrestor it almost seems to be slightly backfiring at idle?? I can't imagine the bike would be running lean/backfiring with the 48.
-I checked TDC with screwdriver thru spark plug hole and it was true with the I mark after H mark thru inspection port. I got my exhaust cam mark as close to 9 oclock and intake cam mark as to 3oclock as I thought possible. Pin count was 13 between the two top marks on intake and exhaust cams. I lubed cams with bel ray assembly lube. Pics are below, sorry the pic quality is pitiful but it's all I've got.
-Is my timing off or are there any other beginner mistakes I could've made to cause this? Thanks