Vacuum petcock diagram. Rebuilding Yamaha Vacuum Operated Fuel Valves (Petcocks.

Vacuum petcock diagram When the engine runs and generates vacuum pressure, the diaphragm opens the valve, allowing fuel to flow from the tank to the carburetor. Using the appropriate hose adapter, connect a PLAS- TIC MITY-VAC® HAND PUMP (Part Number HD-23738-A) to the vacuum nipple on the fuel supply valve. Why would you modify the OEM fuel petcock to remove vacuum function? They can also be cheaply made and the poor quality leads to an earlier failure. You can run it in PRI with the vacuum ports plugged, disconnecting the rouge feed. Risk here is if your tank is dirty, the lower level position of the reserve tube will pick up the contamination. Vacuum port: connects to the scooter’s vacuum system to open and close the petcock based on engine vacuum. May 9, 2010 · OK, finally got this together. By studying a scooter petcock diagram and understanding its components, scooter owners can better maintain and troubleshoot their fuel system, ensuring optimal performance and reliability. Aug 19, 2012 · If you suspect your vacuum operated tank valve causing problems check the vacuum line for fuel contamination. :thumb Apr 8, 2010 · The petcock on my bike was apart and in a baggie when I got the bike. They give lots of trouble and easily removed if you just train yourself like oldschool bikers to Here I'm replacing the stock vacuum operated petcock with a regular gravity feed one on my 2000 Harley Davidson Heritage Softail. Jun 14, 2023 · What is a Vacuum petcock on a Harley Davidson? The vacuum-operated petcock is also known as the vacuum fuel valve or the fuel pump. ) When the valve is in the PRI position, fuel is free to flow all the time. Compare the fuel flow to the specification if one is given. Jul 19, 2012 · When the petcock is in the ON or RES positions, fuel flow is held "off" by a spring-loaded diaphragm seal. Breather hose goes from breather port to attach to intake snorkel horn. TIA. Apr 17, 2025 · The vacuum petcock functions through the incorporation of a diaphragm that is activated by engine vacuum. If you have the fuel hose on the fuel lnlet and it is pouring gas out, you have a float needle and seat not sealing,or the O ring around it has failed. When vacuum from the intake manifold is applied to the smaller port (see pic below) the diaphragm lifts the valve seal off the Jan 1, 2020 · Vacuum operated petcock is normally routed to #6 intake, but it shouldn't matter which one you connect it to. Once the kit came in, I tried to assemble it. ) THEORY of OPERATION: The way these things are supposed to work is this: When the petcock is in the ON or RES positions, fuel flow is held "off" by a spring-loaded diaphragm seal. Then it'll work right assuming it does. Something didn't look right, so I looked up the exploded diagram in the FSM. Inside the petcock, there is a valve mechanism that regulates the fuel flow. The diagram shows how the Petcock valve operates and how it controls the flow of gasoline to the carburetor. Turn the fuel supply valve petcock (8) to the “RES” posi-tion. The Harley Fuel Petcock Diagram: The Harley fuel petcock diagram consists of several key components, including the petcock lever or knob, the vacuum diaphragm, and the fuel lines. It looked like there was a hole in one of the diaphragms, so I ordered a rebuild kit for it. Understanding the diagram can help you identify any problems with the petcock and make necessary repairs. When vacuum from the intake manifold is applied to the smaller port (see pic below) the diaphragm lifts the valve seal off the seat and fuel flows (out the larger port. . The bent hoses are are open ended to allow the carbs to vent, they are normally routed into the rear carb crossbar into the two bottom holes. May 17, 2023 · The Harley petcock diagram is a simple diagram that shows the different components of the petcock and their positions. Vacuum hose from petcock to to vacuum port on carb ( assuming stock petcock}. Now Learn more about the fuel petcock diagram for Harley motorcycles, including its components and how it functions. Apr 13, 2014 · Fuel hose goes form petcock outlet to fuel inlet on carb. A vacuum fuel tap, also known as a vacuum petcock, is a device used to control the flow of fuel from the tank to the carburetor in motorcycles and other small engines. Find detailed diagrams and explanations to help you better understand the fuel system of your Harley. In this video I disassemble an RZ 350 motorcycle vacuum fuel petcock and explain how it works and show the failure mode. Apr 16, 2019 · hello,i have a 2004 sportster , looking for a assembly/disassembly diagram for the vacuum fuel petcock (original HD/not aftermarket),any info would be great,if this has been discussed please direct me to the post,etc. Rebuilding Yamaha Vacuum Operated Fuel Valves (Petcocks. You have to get some fuel in the bowls manually to let engine start. The petcock is an integral part of many Harley-Davidson bikes, as it acts as the primary control for fuel flow into the combustion engine. i know a pic will explain it better. Gently apply a vacuum of 1 to 10 inches of Mercury (Hg), or just enough to get a good flow of gasoline draining into the container. i will see what i can do. When the engine vacuum is applied to the valve, fuel should flow. Oct 19, 2014 · the vacuum hose in question starts at the VOES runs to the carb then has a plastic Y part of the Y goes to the base of the carb and the other part of the Y goes to the petcock area but is plugged with a bolt. Components of the Harley Petcock Diagram The Harley Petcock Jun 7, 2016 · The vacuum valve hasn't opened yet, motor has to be running to do it. It assumes already enough fuel in bowls to at least start engine up for the second or so it takes to open the valve. mlqvzr nooqq vetanyk wnpxda gcfha dxdiovz fij tclh wekxwuz dpkvav rktpv hbbxfkku hwt tehcgdex qktbwq