Have an 04 low rider, after a ride yesterday plug came out while riding happened once before last year, just put back in and tightened was ok. the motor had work to increase size is it possible the correct plug could be a tiny bit bigger than one that is in there....

 

What plug are you using?

 

Something is definitely wrong....Plugs don't just fall out of the motor. I would check to see that the threads in the head are not stripped or damaged as I have never in all my 25 years of riding and 30+ years of wrenching have I heard of a sparkplug coming out and with no damage to to the threads. If the threads are damaged you can do a fix fairly simple with a spark plug thread chaser or if necessary you can get a heli coil kit to fix the problem. They are available at any good auto parts store or on line. Take a look and let us know what you find.

 

Wow, that thing could potentially have shot outta there like a 50 cal. Better get to the bottom of that and soon. Surprised the plug was able to rotate that many times within the boot. Live long enough you'll hear everything. Keep us posted please.

 

I would look into that a little closer. Spark plugs dont just vibrate loose and the plug wire shouldnt let it rotate that much. Something else is going on here.