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Hi, just got a 1997 Blackbird and have it a good strip down and clean. Found a pair of hoses under the tank not connected to anything. Hose lying either side of carbs and connect via a t-piece with drain going down by front sprocket. The pipe on the right hand side of the frame seems to be held by a we metal bracket if that helps. Any idea what this is from please?
 

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I think it's the fuel tank vent line your looking at. The "Tee" connection ensures that the line never builds a liquid level which would effectively shut down the venting action from the fuel tank. If you will imagine a bathroom sink "P-trap" which seals off the sewer pipe from the house because of the liquid level in the trap....this is something that we DO NOT want to happen with our fuel tank venting. If the tank vent shuts down/plugs off, fuel would cease to flow at some point in time. As fuel flows via gravity to the carbs float bowls then air must be allowed to enter the fuel tank to keep the fuel flowing. Some pictures of the system as I see it are located here: (see link).

https://www.cbrxx.com/engine-airbox-exhaust-fuel-delivery/26728-breather-pipe.html#post368230

A couple other graphic's help show the function of the vent hoses, attached below. When you route your vent line ensure that there are no loops, dips etc in the hose run that might trap liquid which would shut off the venting action.

HTH,

T.
 

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