Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Raphael by all means try another spark plug. It might make all the difference. My engine seemed to be very tricky on mixture adjustment. After changing the spark plug to a good quality one, all of a sudden it doesn't matter anymore. It will run at 3/4 turn open, but run just as well on 1,5 turns  open with no noticeable difference in how it runs. Give it a try, you'll be amazed. I am using a Japanese one. Or at least it has Japanese text on it....