Here's what worked on my very first wobbler:
Short runs only in both directions. The engine performing much better on the 'recharging' stroke, hindsight obvious.
then came a bicycle pump, a dual action hand pump (that was for continous duty), ...
...even used air from a scuba bottle, but that 200bar source was scary.
Of course, THE AIR LINE WAS NOT RIGIDLY CONNECTED TO THE BOTTLE: I only held the pipe close to it by hand.
The engine run rather fast, I would have not been surprised had I had it exploding.
Now, I'm the proud owner of the noisiest commercial 25lt / single cylynder / oil-less air compressor ever produced.
Manages to be a real pain, though enclosed and set into another room.
't was the cheapest, You bet.
Marcello