I have a -11PRMK that for one reason or another spits pout the spark plug on the clutch side, this has happened 3 times now over a two year period.
I've checked the threads in the head with a thread gauge and can't find any deviation here.
So...any tips or hints?
Have you installed them with a torque wrench? If not, do it to get a feel for how tight they need to be. If not tightened enough, they'll back themselves out. Tighten to 18-22 ft-lb. Probably not your problem, but worth checking.
