Help leaking gas and caught on fire!

You probably ought to install an in-line fuel filter suitable for motorcycles. some from the auto parts stores don't flow enough fuel.
Also, I would do something about the fuel cap asap. If getting used, I don't recall if you have to have the correct key or if any old key will open them. I installed an aftermarket fuel cap that looks identical to the stock unit. I think it was made in Taiwan.

1981 KZ650-CSR fuel tank with Aftermarket fuel cap.