I just installed NGK DCPR7E spark plugs ( integral nipples or really tight since I couldn't unscrew them ) because my Autolites with screwed on nipples kept loosening up as well. If I remember correctly Harley Davidson equivalent spark plugs may also have integral or really tight nipples.

Last edited by Sportster; 18/05/17 03:30 AM.
2015 M3W, Morgan Aero Racing Stage 1, Garage 56 Stage 2, sport black, saddle tan, jeweled SS dash.