since your boyer is "brand new" and your attempt to kick start yields a kick back, that sounds like you are too advanced. Whether that is because you set your ignition up too advanced or your carburation is too lean, finding this out will be part of your discovery process...
Reread the boyer installation guide for the initial set up. Check that your magnetic rotor hasn't slipped it's position. Verify that the rotor is set at the proper angle (refer to the instructions)
Pull the plugs and inspect them. Is fuel getting to them? Are they wet? Are they dry??
Because you are getting a kickback, you know you are getting spark but you don't know that it's timed correctly. Spark timing and mixture are related. Meaning that if you are only a few degrees too advanced AND you are too lean of a fuel mixture, you will get a kickback because that lean mixture burns quicker which amplifies the effect of your timing being advanced... Kickback!
So, try this to start the bike. Don't use the choke. Bleed the bowls if you have amals. Hold the throttle half open and kick the bike over. It may roar to life and die if you release the throttle. If that's the case, then that may indicate clogged pilot jets on amal carbs if that's the carb you have...
without knowing what your carbs are, I can only guess.. HTH