Spark Plug keeps coming lose?

[Jesse_James]

I am wondering why does my spark plug keep popping out of the engine? I have the spark plug REALLY tightly screwed into the engine but somehow it manages to come lose and pop out as I ride. It is left hanging by the CDI spark plug wire. And BTW that stock bootcap that fits onto the tip of the spark plug is REALLY CHEAP.

 

[2door]

How tight is "really tight"?
Some kit instructions tell you to finger tighten the plug. THIS IS WRONG!. The spark plug must be tightened with a wrench or socket. If you use a torque wrench go for about 80 to 100 inch pounds. That is a lot tighter than "finger tight". If you are using a socket and tighteneing the plug then I'd start looking at the threads in the head. Did you overtighten it and possibly strip the threads?

As for the plug boot; it is by far the weakest link in the kit and should be thrown in the trash during unpacking the kit the first time. Replace it with a good automotive quality boot available at any auto parts store.

Tom