Almost positive they were NGK. I bought them from the local Triumph dealer - same # as OEM. What I'm still curious about is how/why it happened (so it doesn't happen again). I was cruising along at a sedate 50 mph, though I did have a spirited 20-80 mph run-up about 10 minutes earlier. Maybe a bad batch of plugs.
It was a mystery to the mechanics too. After the plug change and over a 2 day period, they rode it 35 miles, with 3 separate warm up/cool down cycles and had no misfiring. Another 15 miles on my way home was the same.
