Part of every VB series carburetor rebuild is making sure the accelerator pump system works properly. The pump itself usually needs rehabilitation, and the nozzles are often clogged with a mixture of fuel resin and rust. Gentle heat softens the resin, then the wire is stuck into the nozzle to auger out the rest of the obstruction.

The pictures speak for themselves. This is the most effective way I have found to clear th accelerator pump system nozzles. That's a pin vise holding a bit of stiff steel wire. A length of brazing rod provides a handy grip for the pin vise. This is my go-to method.