This kit is used to repair/replace the spark plug cap that is broken or you want to replace the end of an existing CDI and you may need it for a different size spark plug.
It is used for the 3/4” / 19 mm spark plug hex with 14 x 1.25 mm thread.
It was design to be used with NGK Spark Plug brand. Can be used with other brands like Bosch, Autolite, Champion. One thing need to look for is the way the cap engage the hex.
The spring must go under the hex and not be visible. If the hex is not fully engaged then the top connection will not be fully made and spark will be jumping inside the booth.
If this happens you will be experience radio interference . This is the MOST common cause of the radio interference.