Dimensions: 4.5"L x 2.75"W (114 mm x 70 mm). Gas ball valve with 3/8" (10mm) NPT male thread inlet. E7 removable serrated hose nozzle outlet. PSI: For use with .5 - 125 psi maximum working pressure. Correct , there is no off position on the petcock because the petcock is an automatic fuel valve , opened by vacuum as the piston draws air into the motor . Why not just fix it right and replace the petcock , if the diaphragm is shot ( which I doubt happens very often ) . The petcock can be taken apart and cleaned .
Aug 31, 2016 · With suction applied to vacuum hose, fuel should run freely from petcock to carb. Simple test: Apply vacuum to petcock through vacuum connection hose; fuel should run freely from tank through petcock and carburetor fuel line. Or, yank the fuel line off the petcock and see if fuel runs into a container held to catch the flow.