In this case, there was also a casting defect, one exhaust hole was half clogged from factory, and the finish of the 3 others was really rough. I guess this doesn’t help 🙂
I had to work on them 4 with a Dremel.
I suggest to take a look on other engines when they are in parts, in case they have the same problem.
Thanks for the polish 🙂 As usual, it’s even better in real than on a picture.
Stock ports casting :
