This manual pertains to the Tillotson MD Series horizontal carburetors, produced from 1954 onwards. These carburetors were integral components in a variety of single-cylinder engines, commonly found in industrial equipment, small tractors, generators, and early motorcycles. Tillotson has a long-standing reputation for manufacturing robust and reliable fuel delivery systems, and the MD series exemplifies this legacy, offering practical utility for maintaining and repairing these essential devices. Their historical relevance makes this manual a critical resource for owners and restorers of equipment from this era.

The purpose of this service manual is to provide comprehensive guidance for the repair, parts identification, and adjustment of Tillotson MD Horizontal Carburetors. It covers essential areas including fuel delivery systems, detailed component breakdowns, air-fuel mixture control, idle systems, main jetting, float bowl assembly, and throttle control. The manual offers step-by-step instructions for disassembly, reassembly, cleaning, and overhaul, along with troubleshooting procedures for common issues. This detailed information is designed to assist both experienced DIY enthusiasts and professional mechanics in maintaining the optimal performance and longevity of these carburetors.