I have noticed too that on top of old gas, cheap gas can also affect the way the bike runs. High grade works out really well. But I am in the same boat as you. Started riding in '09 with no real mechanical experience to speak of. Been ok so far with maintenance but I should probably clean my carb myself. Also, one time I put some really high performance Motorcycle oil in it and it really slowed my bike and it would shutter during acceleration kinda like what you are experiencing.
'09 Ninja 250
Last edited by bullet3; 06-19-2011 at 12:08 PM.