Woa woa woa. That is not a z50. That is a spanish style maxi engine made by puch/hero and even has some honda components on it. I have owned 2 of them and you can tell by a few things on it.
1 is the cylinder. The 3 bolt intake is the hero cylinders
2 is the side cover that says puch on it.
3 is the electric start, z50 didnt have that.
4 where is the clutch stuff on the engine? Z50's are 2 speed shifter engines, it would have at least a clutch cable coming out.
5 the way the magneto is setup on this engine. If you remove that cover that says PUCH it will have the stator plate attached to it with the magneto flipped and the dishes side facing out.
Not to say these are not really neat and fun engines, but it is NOT a z50. It should say something like ea50 on it.
Couple things to note on these when buying a new coil for it. It is a cdi setup so you need a controller with your HT coil. The rotation of the engine is like an e50, but the electronics are all flipped with the way they are attached to the engine so the electronic rotation is actually like and za50 so get electric components for that. Took me about a year to really figure that one out. So, you're welcome.
The transfers on these engines are huge, these engines can have a lot of potential for sure.