The only plugs I use are BPR6ES,Cant get BP6ES anymore,the only difference is the R stands for resistor which you should run on fuel injected bikes,dont know why,thats what i have heard and read,any truth or insight on this?I run these plugs in all my cars also,1275 to 1380 A series,mild to wild motors in my Mini,Bugeye,Morris Traveller.Mark.Moto Guzzi Classics