Blumbly, I have had one of those carby's in the past (before I knew how to service them properly) that I gave up on.
I ended up putting a later model tank and carby on (one with a primer off a 35 sprint)
This works aswell, gives trouble free starting.
I have only done a hand full of these engines, I have found in most cases the engine itself it great, just the fuel supply from a tank and carby that requies attention making it run rough.
I place the air filter screw back in during testing, if I have the filter off.
