so I recently bought a friends 03 CBR600 RR I knew there was some general issues (he tore his ACL early last summer and it’s been sitting since then) I’ve gotten most of the issues fixed but when I’m out riding it works perfectly fine for about the first 30 minutes to hour but then it will start spuddering and bucking then will go back to normal but the revs will spike, occasionally the oil light will come on and when you come to a stop after that it will die. I’ve gone through and made sure the oil is at the right level (I have given it a oil change since I brought it home). I’ve been draining the gas from the last time he filled it up, while riding it tonight (seeing if the oil change has helped) it ran perfectly fine for the first hour like normally and right when I got my confidence that it might have been a minor issue it started bucking pretty hard and when I stopped it died, then the battery (that is brand new) won’t turn the engine over and the headlights die, when I bump started it rode fine, until it died again further up the road after another bump start it was fine for the last couple blocks home.

I can say it seems to happen
-around 3,500-4,000 rpm
-in 2nd or 3rd gear
-after I’ve driven over some bumpier roads (I live in Chicago there’s no way to avoid some pot holes)

other possible helpful information
-my friend was running 87 octain gas in the bike until I bought it
-it’s most likely been about 3 years since a spark plus where changed and was on my to do list this week
-I also haven’t looked at the air filter but that was changed relatively recently according to my friend.
-he also just told me he had the entire electrical system rewired before it started sitting

please help even if it’s something beyond my abilities to fix or is an expensive fix I would like to know!

I will take a GoPro video and link it when I’m confident it’s not crazy bad to be on the bike