It's a 750. Funny you should mention a 500. I was looking at one just last week. It is a 1986. It looked to be in excellent condition. I had one of those too, back when I was racing the 750. I didn't race it, but it was a blast to ride. You kinda held the throttle to the stop and shuffled through the gearbox. I had to sell it as I was either going to loose my license or my life. It was a clear cut case of too much fun!