Fuel and Oil taps on DB4

[JeremyB]

I've discovered have a couple of 'undocumented' control valves on my DB4:
- A fuel tap under the tank.
- a tap in the oil lines that preheat the carburettor fuel bowls.

There is absolutely nothing in the Owners or Service Manuals on these, and I wondered if anyone had come across these, and had more info ?.

My questions:
It looks like the fuel valve is OFF-ON-OFF positions, but would one be a 'Reserve' position ? there are no labels, of course. I have the usual Ducati-like 'low fuel' light.

I live in Florida - carb iceing is the least of my problems....
Any advantage to closing-off the oil line that warms the carb bowls, and does this affect the normal lube oil flow. It looks like the oil line is tapped-off the oil
cooler.

Oh - the attached photo was taken at Leesburg BikeFest this year.
This here is truly 'Harley Country' - buried amongst all that American Iron is one lonely Bimota ! There were a one or two other types (there's a Gold Wing in the foreground) but it was 99.9% HD.

[ZAWA]

I think the fuel valve on my DB2 is just off and on, it looks like the ones that have the reserve postion. In theory it might be better but think of were the carbs are sitting, don't think it would make much differance in real world.