No Gas
Seasoned HDF Member
Joined: Dec 2010
Posts: 7,736
Likes: 1,524
From: Coromandel Peninsula New Zealand
Yup, its true, vacuum taps only flow gas if the inlet is "sucking" they are designed to prevent gas flow when the bike is standing. When the diaphragm fails they will flow all the time but the bike will still work so unless your cut off valve goes sick you will never know its happened.
Seasoned HDF Member
Joined: Dec 2010
Posts: 7,736
Likes: 1,524
From: Coromandel Peninsula New Zealand
Pull the fuel line off the petcock. crank the motor on the starter with everything else connected and see if gas flows while cranking (throttle fully open).
If no gas then your tap is either clogged or assembled incorrectly inside.
1: Remove petcock
2: Remove filter from petcock (this is the one that sits inside the tank and covers the inlets)
3: There are two inlets on the part of the petcock that goes inside the tank. The long one (brass or plastic pipe) is your main tank. The reserve inlet is flush with the petcock body.
4: Remove the 4 screws that hold the diaphragm and assorted parts onto the back of the petcock body (square casting) remember how the bits came out.
5: Blow down the long inlet pipe with the gas tap turned to"on"....if no air flows then you have a blockage on the inlet side of the tap.
6: Turn petcock upside down and blow through the outlet, first on "on" and then on "reserve"...air should flow and if it doesn't then you have a blocked outlet.
If you have no flow on either on or reserve from the inlet side then you need to poke about with some wire to clear it but never do this with the diaphragm assy in place.
Good luck!
If no gas then your tap is either clogged or assembled incorrectly inside.
1: Remove petcock
2: Remove filter from petcock (this is the one that sits inside the tank and covers the inlets)
3: There are two inlets on the part of the petcock that goes inside the tank. The long one (brass or plastic pipe) is your main tank. The reserve inlet is flush with the petcock body.
4: Remove the 4 screws that hold the diaphragm and assorted parts onto the back of the petcock body (square casting) remember how the bits came out.
5: Blow down the long inlet pipe with the gas tap turned to"on"....if no air flows then you have a blockage on the inlet side of the tap.
6: Turn petcock upside down and blow through the outlet, first on "on" and then on "reserve"...air should flow and if it doesn't then you have a blocked outlet.
If you have no flow on either on or reserve from the inlet side then you need to poke about with some wire to clear it but never do this with the diaphragm assy in place.
Good luck!
Thank you guys for all your great suggestions and ideas. After all that work I took the new petcock out and replaced it with another new one. Sure enough the first new petcock was bad. Go figure. So after a few hours work and yet another trip to the the local Harley dealership I have a bike that is running and now it's time to enjoy bike week. Yippie...
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