BoxRec

Any ideas why Kaylor was disqualified against Tony Cerda back in 1983?

Punching after the bell. There is an internet interview with Kaylor, I think on champsuk.com, where he talked about how he just couldn't stop himself.

I have two rounds of the fight, so it must have been filmed.

I just had a look at the last round. Cerda is on the ropes and totally spent. The bell rings and Kaylor lands a left-right to the jaw that sends Cerda flat on his face out to the world for several minutes.
Referee Harry Gibbs has no problems with declaring Cerda the winner on a foul.