I have a EVO 80 inch motor. I tried to start the bike with a battery booster. Lights stop working and now the bike backfires and only stays on for a second. Don't know if I fried ignition or if coil is bad. I have new battery and fresh gas.

If you had a bad coil, the bike probably would not run at all. To check the coil use a DVOM (digital volt ohm meter) and check across the two small terminals of the coil. Take the wires off and put your meter in R X 1 scale. You should have about 3-4 ohms. Anymore than six, the coil is bad.

On a softail, most of the circuit breakers are under the seat best as I can remember. You didn't say what year model you bike was. I don't think they had fuses back then.

Take your spark plugs out and check for spark. If you spin the engine and you get continuous spark, ignition should be fine.

I don't have a schematic handy but it seems to me that the voltage for the ignition goes through the starter relay. Replace the starter relay. It costs about 10-15 dollars. It a one inch plastic cube looking thing located on the front side of the rear fender down low. If you've got a schematic, check for a white wire coming off the relay and going to the top of the coil. Good Luck!

If you used a regular car battery booster yes you could have caused serious damage to your charging system. Way too much amperage for it.