im an automotive tech and it sounds to me like a spun rod bearing. It wouldnt be a bad idea to just pull the valve cover and check that too though. If theres metal in the oil its most likely lower end.

you need new bike you oil pump is bad

gay

Buy a new bike, problem solved

Buy my kawasaki ninja ZX1000 1986 :) theres a good solution!

i dont really know much about bikes but it does sound like a broken rod or a valve dropped. im just guessin cause it almost sounds like car when that happens.

yeah definte carnage probably a snapped rod is my guess good luck post some vids of the tear down .

I work as a kawasaki tech and the sound on my cpu sucks but it sounds to me like a connecting rod has broke and is smashing against the block or more likely you dropped a valve. Dropping a valve would be consistant with high rpm abuse and its age. Its probably never had a valve adjustment. Take the tank off and take the valve cover off and inspect it. If its that you'll need new top end. The other suggestions are all legit possibilities but try the easiest first. i can't remeber on that bike but you may have to diconnect the front and top motor mount just to get the valve cover off. Leave the rear lower mount loose but in place. This should hold the engine in the bike but tilted down enuff to get access. lable your wires and put your hardware in zip locks labled where they go if you get to deep.

Definitely a rod bearing.