Chainsaw Repair

The NGK BPMR7F has 5/8'' flats instead of 3/4'' flats like on the NGK BPMR7A. This tapered seat plug is also shorter than the gasketed BPMR7A.

The Champion RDJ6Y is supposed to be the tapered seat replacement for the Champion RCJ6Y but you cannot depend on the external size of them. The external size is not so important with a rubber boot on a chainsaw but when using a metal shielded cap for Radio Frequency Interference situations, size becomes very important.

The shielded cap for the 14mm BPMR7F also fits the smaller 10mm CMR6H plug that's used in the new 500 series Husqvarnas.

My point remains that the tapered seat plug runs the same as the gasketed plug as long as they are the same thread diameter, thread length, heat range, and type. I've swapped them back and forth and checked with a tach under load in several different engines.