OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Question On Scott Bonnar Cylinder Mowers Scott Bonnar 45 Restoration - newbie

If the third digit in the Model number is a 2, it has Pulsa-Jet carburetor. Here is some information on them, for a start:



Essentially, the things likely to cause poor running are dirt/gum on the screen at the bottom of one of the tubes, or in a jet, metering hole or passage, or deterioration of the fuel pump diaphragm. The page from the manual posted above outlines the cleaning process. Figure 51, at the bottom of that page, shows you how to disassemble the fuel pump to check its diaphragm. If it has become moderately stiff, or the flap valves do not lie flat against the metal surface, you need a new diaphragm. I suggest you disregard Figure 46 for the moment: the spiral is not likely to be a problem unless the carburetor has been abused.