I'm not disagreeing with you, but by shifting the rpm, the engine can be held at higher torque generating engine speeds. I've roadraced and drag raced motorcycles. I've done a fair share of racing. I realize the limitations of the Burgman. But I actually had an opportunity where if I had done the POWER / NORMAL mode shift, I would have faired better against … I think it was a Camry or similar. Just for fun, not for pinks or bragging rights.The power button does nothing more than change the operation of the CVT by adding about 1000 RPMs to the current engine speed/vehicle speed ratio when activated. The venerable 650 is limited on the amount of torque it produces. There is little to work with so they substitute engine speed. By spinning it with another 1K faster it gives mildly better performance. It does help only but only slightly. If you are hoping to win a race with a 650 you need to select your opponent carefully.
As one can imagine a torque and horsepower curve generally have their max and then trail off. With the Power button, the engine gets into the higher torque zone SOONER, but also exits that peak torque zone sooner. At some point past the peak torque zone, if one clicks it back to Normal mode, the engine drops back to (or close to) the peak torque zone and runs through that torque zone again. It's likely in the 60 - 65 mph zone as to where to make the shift (I'd like to pinpoint it with a torque curve). Does it make a lot of difference? Meh … it's not tremendous. But I bet as measured on a drag strip switching back and forth versus just leaving it in manual … with equal riders, I'm betting the rider that just leaves it in manual would consistently get beat by 2 to 4 Burgman lengths (so I'll say 3 Burgman lengths as a guesstimate). We need every advantage we can get to beat soccer moms to the better parking spots! 😁