Air Fuel Value. You said that these mods were done before you got the bike. So with the K&n and hawk exhaust it should have had a tps reset and race map installed. You could try redoing these things to be sure they are done right.
My bike is bone stock with 5k on the odo and pops a little through the intake when blipping the throttle. Also, I think they all pop through the exhaust on decell only you hear it more with the opened up pipe.
That's what I meant, since you don't know the bikes history do a TPS reset and AFV reset. Recheck timing(only takes a minute) and go from there. It's a good idea to reset TPS and AFV every so often anyway.
i did a good wheelie without clutching it in second no problem..I hammered down thru an intersection and accidentally kicked up on the shifter at about 6 grand and she stood straight up like NOW..I just wonder what the people thought ha ha
Easiest way for my 12r is to blip the throttle then when the shocks unload just pin it and modulate the throttle from there. Or to nail it from a stop n when you click into 2nd it should come up and go down pretty smoothly and all on its own. Itll ride it out for little bit too.