1979 GS550E Carbs - missing vacuum hose?

[Thurmanator]

I took the carbs off of my bike today and noticed that there seems to be a missing hose (maybe a vacuum hose?) between carbs 2 and 3 (blue circle in photo). Can anyone confirm that there is supposed to be a hose there and also why or why not?

There was already a hose between carbs 3 and 4 and also between 1 and 2 when I pulled the carbs off of the bike. I went ahead and put a hose between carbs 2 and 3 just in case. I can easily cut it off if it isn't needed.

[Nessism]

The carb bodies are not drilled though on the center carbs, where you marked. That tube won't do any good.

[Steve]

If you look at the edge of the red circles on carbs 2 and 4 (carbs are upside down, so #4 is on the left, #1 is on the right, in that picture), you will see the fittings where VENT hoses are supposed to be attached. The vent fitting on #4 is attached via a short hose to #3 (which you have installed) and, similarly, the fitting on #2 is connected to #1. There should be no vent hose between #2 and #3, just the fuel "T" that is shown just above your blue circle.

Those vent hoses should be routed over the airbox and end up either behind the airbox or under the seat in a pocket of relatively still air. They are the atmospheric reference for the carbs, so need to have calm air at the ends.

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[Thurmanator]

If you look at the edge of the red circles on carbs 2 and 4 (carbs are upside down, so #4 is on the left, #1 is on the right, in that picture), you will see the fittings where VENT hoses are supposed to be attached. The vent fitting on #4 is attached via a short hose to #3 (which you have installed) and, similarly, the fitting on #2 is connected to #1. There should be no vent hose between #2 and #3, just the fuel "T" that is shown just above your blue circle.

Those vent hoses should be routed over the airbox and end up either behind the airbox or under the seat in a pocket of relatively still air. They are the atmospheric reference for the carbs, so need to have calm air at the ends.

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Thanks for the quick, detailed response. I've still got a lot to learn about these things. You've definitely helped.

[Steve]

Ed beat me to it. He posted while I was busy typing details.

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