i have a Honda 300 new wiring harness new cdi box new plug it will start and idle fine but u give it gas it misses and back fires also if you hook up the battery when running it will not idle all it does is back fire you you turn on the head lights it will just die im lost at this point checked every thing in the manual and its all in range it seems like it jumped timing but then also seem electrical any help please

 

check ur timng couldn't hurt check for spark and check to see if ur flywheel is rusted might not be gettn good fire out the stater coil

 

Odd that hooking up a battery will kill it, maybe the voltage regulator is fried?

 

I checked that it seemed to check out what the manuel said im goin to try and find a good voltage reg around and see I hope it only cuts out at higher rpms it idles fine

 

the wires on the back of the key switch broke off an i want to put a new switch in but i don't know what wires are what

 

I would say it's the wrong wiring harness, wrong CDI, or something is hooked up wrong. It's probably something simple like that.