Bought this bike and to my knowledge the jetting is stock. I noticed that when at idle if I crack the throttle open fast it will cut out. Is this normal for 4 strokes or can adjusting the air/fuel screw help that out? Also this weekend it was in the 40's(in va.) and it felt like maybe it was not pulling up top like it should(in 4th gear) The bike has so much power I have been scared to fool with it. Is the stock jetting pretty spot on or can I improve it? Thanks for the help.