Field endurance testing in New Delhi and surrounding area roads demonstrates the potential of catalytic devices for delivering long term reductions of HC + NOx and CO emissions from 2-wheel vehicles. Typically, catalytic performance is monitored periodically using chasis dynamometer mass emission test procedures. Unfortunately, mass emission testing is resource and time consuming. However, there is a relatively simple method for semi-continuously monitoring changes in catalyst performance during road aging. This relatively simple method of catalyst performance monitoring is discussed in this paper. In addition, the impact of extended vehicle operation during field testing and dynamometer endurance runs on catalyst performance is assessed for both 2 and 4 stroke motorcycles. Results examining catalyst deactivation mechanisms are examined for 2-wheel vehicles equipped with these 2 and 4 stroke engines. The deposition of exhaust borne catalyst poisons appears to be the principal factor in altered catalyst performance for 4-stroke powered 2-wheel vehicle, while high temperature operating environments appear to be the primary deactivation mode for catalyst used in 2-stroke vehicles.