Cracked 75 Petcock

[Buckminster]

I have a '75 with manual petcocks. I would like to avoid replacing them and rebuild if possible seeing as they are in fairly good shape. However, the taller integral riser on each petcock is cracked and split almost the entire length (1.5"). I was thinking of slipping a piece of fuel line snug over each cracked risers and calling it a day. Has anyone else dealt with this issue or have another proven fix? Any help would be greatly appreciated.

 

[Royboy]

Just checked a 77" petcock that was laying on the bench. The brass risers mic at 6mm which is just over 7/32nds. 7/32nd brass tube is readily available at hardware stores. It should be possible to drill out the old tubes and replace. You could also go up to 1/4" without changing much. I'd just set the new tubes with a dab of JB Weld. Obviously height of tubes is the critical dimension.

Trying to think why they would have cracked.......only thing that comes to mind is so much water in the tank that they froze and split like a water pipe would.?

roy

 

[Buckminster]

Thanks! I'll look into it. As for why they cracked, that is a great question. This bike was pulled from an old farm shed 15 years ago - where it had sat for quite a while. The petcocks were probably cracked then and my guess is that I cleaned them up just enough to get the thing running and forgot to go back and address the issue correctly.

 

[gggGary]

Cracked tubes are common. I have wrapped some copper wire around the tube and soldered it.

 

[XSLeo]

The reason for the tube is for the reserve fuel function of the petcock. If you notice there are two tubes, one tall the other very short. With a full tank, the petcock in the on position fuel flows through the tall tube. Once the fuel level gets down to a point it can't flow into the tall tube the engine quits. You turn the petcock to reserve and fuel then flows into the short tube.
The height of the tall tube determines the amount of reserve fuel in the tank. A taller tube leaves more reserve, a shorter leaves less.
In my Honda CM400E the tall tube was so tall it hit reserve at around 75 miles. that left about a 2.5 gallon reserve. I cut the tube off about 1/2 inch. It now goes about 135 miles before reserve.
Leo