Does a 1991 Mach 1 ski-doo have push button reverse?

No, a 1991 Mach 1 Ski-Doo does not have push-button reverse. This model typically features a manual reverse system, which requires the operator to engage reverse gear through a lever or handle rather than a push-button mechanism. Push-button reverse was introduced in later models of Ski-Doo snowmobiles.