My friend's 600 has a dead battery. i know that it is possible to jump start a bike by pushing it, switch to first gear with full throttle, and press the ignition. i have done it a couple of times for my 250. but when i did it for the 600, the engine had poping noises kind of like back-fire. I dont think it is anything too serious because my 250 did the same thing when i jump started it, but is it common for it to do that? So did i totally f*ck up the bike by trying to manually start it or is the back-fire noise just a side effect that will go away later? PLEASE help!

thanks