GT:

You are supposed to use one of those needle valves, not both. I'd recommend that you remove (or just bypass) the rear one.

The absolute best way to adjust the carb on a model engine is to find someone who knows how to do it and then watch and ask questions. It is not hard to do, but is very hard to explain.

If you can't find an experienced RC flyer to help you then carefully follow the instruction book.

Jim