Well, i've heard people use NAPA 6962 for the HA4 (660cc) Acty's. I've used them and they work, but i'm unsure of the actual NGK plug that is OEM...? Does anyone have the OEM NGK plug number? -mark
The NGK plugs are BKR6E-11. The NGK number breakdown is as follows B = 14mm K = 5/8" hex R = Resister 6 = Heat range with 2 being hottest and 12 coldest E = 19 mm reach 11 = .044" gap You can go one heat range ether side of 6.