Untitled (117)

# Untitled (117)

Author: coll0412

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The [petcock of the GS](/petcock-and-petrol-hose-routing/) is normally activated via a vacuum. Under [certain circumstances](/dies-whilst-riding-at-full-throttle/) it may be helpful to convert the petcock to a manual one. This is described here.

'''How to convert your 1989-2000 vacuum petcock to work without vacuum with a simple flat head screwdriver.'''

1. First let's define how the petcock works before the mod. Putting the selector on "ON" allows fuel to flow from the "ON" inlet to the ENGINE when there is vacuum on the vacuum port. Putting the selector on "RES" allows fuel to flow from the "RES" inlet to the ENGINE when vacuum is in the vacuum port. Putting the petcock on "PRI" allows fuel to flow from the "RES" inlet to the ENGINE when there is NO VACUUM

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2. Remove the bent metal sheet metal cover by lifting the two tabs and pulling the selector lever up and the bent sheet metal piece will come with. Put it down on the desk and do not disturb the orientation!

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3. Rotate the blue selector valve 180° degrees from the factory position. I used a large flat head screw driver to rotate it 180°.

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4. Take the selector valve and rotate the entire assembly, being careful not to disturb the sheet metal bracket to selector valve orientation. Rotate entire assembly 180° from how it came off and install back onto the petcock (DON'T FORGET THE SPRING).

5. Now lets check the operation.(NOTE: THERE IS NO VACUUM REQUIRED FOR THESE FLOWS, YOU CAN CHECK BY BLOWING ON LINES TO SEE FOR YOURSELF!)

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Effectively the former "ON" inlet is now the "RES" inlet,

the former "RES" inlet is now the "ON" inlet,

and the "PRI" position shuts the flow of entirely.

To correct for this you need to switch your RES and ON fuel lines at the tank( or just remember it's backward!)

'''Bear in mind: From now on you have to switch your petcock to "PRI" (i.e. "OFF") everytime you park your GS for longer. Otherwise (in the common event of a broken float needle valve) you'll drain your tank via the carbs and airbox on the street.