Another way: I use a disposable plastic hipodermic (whitout needle). I put 4.5 cc on my Stromberg ZS175. It is the volume needed to fill the dashpot without overfill it.

The first time I retire the air filter, and move the cylinder up with a finger, after it, I fill oil from the hypodermic on small bits, putting the piston on and cheking overfilling each time. I overfill at 4.7 cc, then I know i will be use the previous dose: 4.5 cc.

You can made a similar measure for your carb(s).

On following refills, I take all old oil out with a syringe (with a bit a plastic tube as a extension - plastic tube taked from a venoclisis kit - easy on any pharmacy - or from a "pajilla" - popular adminicule for drink coca cola, sorry I dont rename the name on english), and refill it with fresh 4.5 cc dose (I use ATF and the quarte bottle has a lot of doses, no problem on spare some cc of oil).

Happy volving
--
Joaquin (yogui the bear) / Rojo 121 / Lima, Peru