GS500 Loss of power and fuel tap

[TWSSwinderby]

Does anyone have any thoughts on what could cause a sudden loss of power when cruising along at about 70mph which over a few miles slowed the bike down until it eventually stopped?Loads of fuel in the tank and after cooling off bike restarted, and also could anyone explain how the early EK model fuel tap works with the vacuum connection from the carbs and the position the tap needs to be in for normal running.Many thanks

[Kerry]

could anyone explain how the early EK model fuel tap works with the vacuum connection from the carbs and the position the tap needs to be in for normal running.

Use the ON position (down) for "normal running".

Use the REServe position (forward) when the bike does what you just described.  Then fillup at the nearest fuel pump.

If the same thing happens while you're still on the REServe position, switch to the PRIme position (up) to eke out another mile or three before you switch to "footmobile" mode.

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The ON and REServe positions flow fuel when the engine is running and NOT when it's off (because of the vacuum hose, etc).  The PRIme position will flow fuel regardless, subject to gravity only.

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PS - That pesky fuel level in the tank can be VERY deceiving.  Fill 'er up and see how much you can put in before deciding that you had "plenty".  The last gallon (~4 liters) or so is only available via the REServe and PRIme positions.  If you can put in 3 to 3.5 gallons (~11 to 14 liters) then your fuel level was low enough to explain the bike's actions.

[Alias]

Mine does the same thing. But it makes no sense. Everyone syas its Vacume related. The previous owner somehow removed teh vacum line to the Petcock, blocked it, and made it work.

[Kerry]

Mine does the same thing. But it makes no sense. Everyone syas its Vacume related. The previous owner somehow removed teh vacum line to the Petcock, blocked it, and made it work.

I'm curious.  Does your engine run with the petcock in any of the 3 positions?  (ON / RES / PRI)

If so, then perhaps the PO removed the petcock diaphragm or something.  :dunno:

If the petcock only works in the PRI position then it would confirm the "vacuum" theory.

[Alias]

Mine does the same thing. But it makes no sense. Everyone syas its Vacume related. The previous owner somehow removed teh vacum line to the Petcock, blocked it, and made it work.

I'm curious.  Does your engine run with the petcock in any of the 3 positions?  (ON / RES / PRI)

If so, then perhaps the PO removed the petcock diaphragm or something.  :dunno:

If the petcock only works in the PRI position then it would confirm the "vacuum" theory.

Bike runs in all positions. I'm curious as to how it does. When its hot out it will lose power ont he highway and run lean. I can look down at my fuel filter and its bone dry. I have to pull over and wait for it to cool. Then I can slowly watch fuel flow back into the filter, or I can "pump" it into the filter by squezing the fuel line.

[Kerry]

When its hot out it will lose power ont he highway and run lean. I can look down at my fuel filter and its bone dry. I have to pull over and wait for it to cool. Then I can slowly watch fuel flow back into the filter, or I can "pump" it into the filter by squezing the fuel line.

If this happens again see if you can get the fuel line & filter to fill up any faster by opening the gas tank filler cap.

If so, then we're back to a vacuum problem!  Only this time it's in a different part of the fuel delivery system - the gas cap.  I've heard tales about a vent hole, but I haven't looked for it (or photographed it  ) yet.

Anyone?

[Alias]

Already tryed that   Didn't seem to help. It doesn't seem to matter how much fuel is in the tank either. There is a vent in the filler hole. I should get a picture of it for you guys. Wanna know something funny? At one time I was like you and had pictures of EVERYTHING. Then I sold my F-717 to pay some bills and I'm stuck with a craptastic Canon.

[Kerry]

Already tryed that   Didn't seem to help. It doesn't seem to matter how much fuel is in the tank either.

Hmmm.  So, all that your ON / RES / PRI petcock gives you now is a RES capability when you run low on fuel.  Can you live without that?  If so, then you could try running a fuel line straight from the forward outlet on the fuel tank to the lower T-connection between the carbs.  (You could even use your inline fuel filter as a makeshift quick-connector if you'd rather test the setup before removing -- or cutting -- any fuel lines.)

If that doesn't work then I would check for some kind of air blockage in the hose or hardware leading to the upper T-connection between the carbs.

Otherwise I'm about out of ideas.  :dunno:

There is a vent in the filler hole. I should get a picture of it for you guys.

That would be great.

Wanna know something funny? At one time I was like you and had pictures of EVERYTHING. Then I sold my F-717 to pay some bills

You sold the camera, but what happened to the pictures?     Or were they not pictures of the GS500?

I have a decidedly consumer-oriented Kodak DX4330.  But at least I'm getting some idea of what I'll want in my NEXT camera....