Reply To: Johnson 6: No spark on both cylinders

[David Stanton]

I haven’t seen a difference in the 6 HPs like yours between Champion J6C and NGK, but then I haven’t worked on very many of those 6s. but on a 9.9 from the 1970s, nothing I could do would make it idle good enough for trolling with new Champions. I switched to NGKs, just because I had some, and it ran perfect. It made me a believer in NGK for the 1970s 9.9s. Based on that, I figure the NGKs should best for some other motors too. In some late 1980s/early 1990s 15 HPs, that idled acceptably with Champions, switching to NGK made them idle/troll fantastic. Others here have reported similar results.
Dave