The present experiment is carried out to study the effect excess cooled exhaust gas recirculation (EGR) on four-stroke, single-cylinder, air-cooled direct injection (DI) diesel engine. The biodiesel used is 100% JOME (Jatropha Oil Methyl Ester). Here jatropha oil methyl ester fuel is transesterified to reduce the viscosity as per ASTM standard. The experiment is conducted by different BMEP with a constant speed of 1500 rpm. An Extensive level of EGR (up to 75%) was used to achieve lower emissions. Experimental results were showed a reduction in NOx higher rate compares to another emission. Exhaust gas Emissions of hydrocarbons, Nitrous oxide, carbon monoxide was measured using gas analyzer. Thermocouple mounted on tailpipe is used to observed the exhaust gas temperature. The calculated thermal efficiency and exhaust emissions are compared with diesel. Reduction in NOx was 62.5% at 75% EGR at 50% load was observed but hydrocarbon, carbon monoxide emissions are increased with rising of EGR percentage. © 2020 The Authors. Published by Elsevier Ltd.