dyno cam

I installed a header, dyno cam, and 18lbs springs. It idles perfect but one you give it throttle it hesitates and backfires. And if you give it throttle and hold it, it has uneven rpm and like its restricted. I DONT HAVE INTAKE OR BIGGER JET. AND STOCK FLYWHEEL. .....HELP

I installed a dyno cam inst my preadator and it has crazy compression. Almost pulled shoulder out trying to start it. I tried lashing valve and didnt work. I have ordered 18lbs springs. Only mod I have is header. WHAT IS THE PROBLEM? HOW CAN I LOWER COMPRESSION SO THAT I CAN START IT?