Here are the concepts involved with checking your accelerator pump. When high performance 4 strokes came on the market there was a flood of new products & hacks meant to "fix" accelerator pump issues. With a basic understanding of the accelerator pump you don't need any of them.
I should mention that the oring mod can be effective if the leak jet and timing screw are set up to accommodate it, but in my experience it usually just masks the real issue.