My brand new 2005 Bandit 1200S pings a little on just 87, it also runs a little rougher. When the tank was half full of 87 I put a half tank of 91 which brought the effective octane level probably to around 89 and it ran immediately better and smoother with a bit more snappyness. I know it's not good to use 2 different brands so I'm going to try a tankfull of premium at 91 and a tankfull of 89 which it probably needs. I was losing power and pingin when full hot with 87. My GS750EF was the same didn't like 87 but 89 worked well, anything over that there was no difference but in my wallet. Stuck to 89 with no probs. I'm also only 500 ft above sea level so it probably needs that extra 2 points on the octane scale.
