Enriched biogas is a promising alternate fuel candidate for compression ignition engines which are used in transportation sector. However, utilization of enriched biogas in compression ignition engines under dual-fuel mode suffer a major problem of high hydrocarbon emission particularly at part load operations. Main causes for this problem are inadequately understood which foils for active penetration of dual-fuel technology in the automotive market. To address this research gap, the current work is focused to investigate the effects of flame quenching and crevice gas (i.e., trapped between cylinder barrel and piston rings) on hydrocarbon emission formation. Investigation was carried out on enriched biogas dual-fuel engine of 3.7 kW rated power at 1500 rpm at part load of 50%. It was explored that both quench and crevice hydrocarbon emissions together are in the range of 60% to 92% of total hydrocarbons. Total hydrocarbon emission level increased from 2 g/kWh with base diesel operation to 56 g/kWh with 77% enriched biogas energy share. Overall, it is emerged that the crevice mechanism plays a dominant role for high hydrocarbon emission levels in enriched biogas dual-fuel engines.