In General the CDI either WORKS or DOESN'T WORK. If it works, it is not the cause of your poor running. You probably have carb issues, possibly less likely, but still possible seals or reed issues. The DuraForce engines are jetted at the very edge of running satisfactory (very lean), when fresh and new. Any, and I mean ANY slight build up of varnish, or any type of detrius in the jets will cause poor running, or NO running. Also you need to make sure you have a perfect seal between the carb and the reed plate.
