If you're not satisfied with the above simple diagram and you want to know everything that there is to know about Tillotson HL carburettors, how they work and how to service and maintain them, then you're in luck. The Service Manual is available for downloading as a Microsoft Word document. Be warned - it's a big document, and Netscape users must pay careful attention to the instructions for downloading, but it is worth the effort. When you're finished, close the page to return to this page.
You can also visit the rest of Tillotson's website. It's an excellent site although, unfortunately, it's not very browser friendly. You'll need a fairly up-to-date browser and a Flash plug-in, but it is worth a visit.