The YS is a bit different then any other four stroke so you can't compare it to an OS or Saito. If you read the item I posted it will show you. The diaphragm is inside the regulator housing. Just two screws gets you there. I don't know the model of engine you have, I have a couple of the 120 models, the NC F and FZ. I know nothing about the DZ models.
What mistake most people make with a YS is they can't keep there hands off the big brass regulator screw!!!!!!!!!!! It's easy to adjust on the FZ model but to tune the others that don't have the low end adjuster screw you have to balance the high end and that brass screw.
It's all covered in the YS forum or on a hundred different how to articles. The big trick is to keep your hands off things once the engine is in tune.