I love my 2013 690 Duke. I've ridden it 600 miles in a single day at speeds of 75-85mph the whole time. The dual plug head really cut down on the vibes compared to my old 640 Adventure. That bike would shake itself across my garage when on the center stand. I also have a two stroke KTM 250XC that is street legal so I can get from trail to trail legally when I hop on the street. My 250 calls for a 50:1 mix ratio. I used to run 32:1 in my older two strokes. Some bikes now even call for 60:1. If your jetting is good you won't foul plugs. If you are real worried out it just pull in the clutch and wring it out every once in a while. I know some folks are using iridium plugs as well.