NGK Spark Plug for all Auto-Glide models. This is the recommended plug for the Ridley 750 V-Twin Engine. Ridley recommends replacing fouled spark plugs. Cleaning fuel fouled plugs never completely rids them of the damage caused by the fuel. You should also replace plugs as part of normal maintenance. For maintenance schedules refer to the Service & Maintenance Guide or Service Manuals available on this site or through you Ridley Dealer.