So, after using autolite 4164 for over 100k miles, decide to try the NGK iridiums since so many said they had good results. after about a month of use started to get an abnormal vibration, so of course ruled the plugs out since they were basically new and only had about 1500 miles on them. Wasn't suspension because vibes would also happen in neutral, so started to look for carb issues, well, lo and behold, my carbs accelerator pump ckt was failing, took care of that issue....still the bad vibration........hmmm, then started to get some real minor decel popping, just enough to tell me air leak, come to find out I did not seat the carb completely in the manifold boot and clamp was a bit off kilter, ok, got that fixed...still the bad vibration, so much that this past Saturday ride, right hand went numb.

This morn, went back to my autolites plugs........vibrations gone!!!

Hard to believe that the plugs broke down that quickly, oh well, live and learn.