Harley 45 Spark Plug Cross Reference Chart

HD plugs - Higher # = Colder Heat Range

American made plugs - Higher # = Hotter Heat Range

Foreign made plugs - Higher # = Colder Heat Range

                                   

18mm plugs

Original plug Equivalent modern replacement Application
HD #3 Champion D16, NGK A6 Normal riding
HD #4 Champion D14, NGK A7 Fast riding
HD #5 Champion D9 Real hard riding

 

14mm plugs

Original plug Equivalent modern replacement Application
HD #3 Champion H-10C, NGK B6L, Accel 2402A or Y2402P Average or normal riding
HD #4 Champion H8C, NGK B6L, Accel 2402 Faster than normal riding
HD #5 Champion J-6C Hard riding

 

A sparkplug cross reference chart should be simple, however I have researched several different sources and found discrepancies in cross reference to HD#'s and replacement plugs. The How To Restore Your Harley Davidson book has the equivalent modern replacements listed in reverse of the correct order I found from other sources. I want to get this chart correct, if you see something on here which is not right, please let me know and possibly provide a reference..

Press Back button or Home