Are these motors designed to run when they are inverted? I have one that starts and runs great. It is mounted upright. When I flip the airplane to inverted while flying it stops running.

Thanks Joe, that's very helpful. Will a black widow run inverted?

There are two more ways to beat the system with a Babe Bee.

One way is to mount the engine with the NV and vents inboard and hold it so the fuel doesn't spill until the launch.  Then you can have the launcher top off the fuel just before launch.  You will get air into the vents without spilling any fuel.  Of course the pickup needs to be moved the new outboard position.

The other way, which requires the drilling of one hole the tank and hooking up an external stunt tank.  US kids figgered that out in 1959.  All the Babe Bees at the Cerveny school had TeeDee cylinders and heads and outside tanks by 1960. 

          Another option is to find a piece of fuel tubing that fits the filler nipples tight. Run the piece of tubing from one nipple all the way around the tank to the opposing nipple. Directly on the bottom opposing the fillers, cut a V notch in the tubing, this will allow for inverted flight

Babe Bee is always clear anodized or silver aluminum.
They have a 5 cc tank with no tubes sticking out, and the backplate has either one filler nipple and a vent, or two nipples. Since fill/vent is topside, well, it normally only runs with the backplate upright.

Black Widows and Golden Bee's have their obvious color. However, they hold 8 CC's, and the backplate has no vent/fill.
Instead the vent/fill tubes are on the tank. One from topside going down to just above the inside/bottom of the tank. The other enters the tank from below, and stops just inside/below the top of the tank. Basically, the tubes are set up like a wedge tank.
As long as the fuel pickup tube makes it to the outside, and low on the tank, the BW, GB backplate could possibly be in any of the four possible positions (needle upright, to either side, or down).

For a while, I ran my Golden Bee sideways with the cylinder out starboard, and the needle to inboard. No upside down landings were going to take out my glowplug or needle!
The tank tubes still went up and down.
Oh, and those fill/vent tubes...ISTR they fall to one side or the other of the venturi. You want them inboard so they don't syphon fuel through the whole run. If they are outboard, they are syphoning-out fuel longer.

never thought about that ,good idea

            The Golden Bee will run inverted just like the Black Widow. Nothing needed to do in order to do so. These engines though don't really tolerate inversion for too long regardless of how they're designed. If you want to go inverted, it's best to do so early in the flight when the tank is full. The need to flip upright can become readily apparent when needed. Outsides, and other maneuvers involving inverted  can be obtained but sustained  inverted flight for too many laps can starve the engine of fuel and it can quit.

All the tanked bees are essentially the same.  The fuel ports are either in the back or the tank, with a fuel pickup hose that must be located where it will do the most good. 

Go here
https://coxengines.ca/engine-and-fuel-guides.html

Look at this document

Gibeault Mouse Race Program

The only difference is he shows making a metal pickup tube, and not the stock one.  The other modifications are optional.  Good pictures with descriptions are hard to find is all, the other user guides are at that link too.

Phil