Re: Brand new engine has hole in cylinder near stud. :(
If I were looking to repair this I'd first pull the head and look down the stud to see if there is any gap at all between the stud and the bore. If there is some room then it would be possible to slip a thin piece of gasket or paper card stock wrapped around the stud down to where you can see it thru the hole. The best way would be to pull the cylinder off off the engine and pack the stud bore where the hole has the best backing before applying the JB Weld to
build up that thin area. But that's a piece of work for a novice. Consider the buyer expects rightfully to receive a motor kit that is free from flaws such as this one.
At that point there is a backing to the hole that the JB Weld or Liquid Steel could be applied to and the gasket serve as a barrier between the cylinder and the stud itself. The gasket material could be left in place until such time as the cylinder is pulled for honing for new ring(s). By that time the gasket material may only be ashes.
As has been pointed out water or condensation entering thru the hole in that area could lead to a build up of rust or corrosion and create a condition that would make it difficult to pull the jug when the maintenance interval comes.
I think this issue should be posted far and wide so those producing these cylinders will make the necessary changes to the molds. If the word gets out
and sales slow on this motor kit then that will motovate the corrective measures faster than anything. If this was a complete motor vehicle from China there would be a recall.