Installed my second set of original-equipment rollers last week, with 6616 miles on the clock. Stock rollers are 20mm x 15mm and 17.5gm. With fresh rollers, throttle response returned to as it was new: Clutch grabs around 3500rpm. With WOT applied from a stop, RPM climbs to 7000rpm (horsepower peak) and stays there until the transmission variates. Then, it climbs to 8000rpm (and beyond).
Today, I swapped in a set of Dr. Pulley 20mm x 15mm sliders, listed as 18gm weight. I chose 18gm based on proposal that sliders behave like lighter conventional rollers. With the 18gm sliders, the most obvious change in performance has been when WOT is applied from a stop: RPM climbs to 6250rpm (torque peak) at launch and winds up to 7000rpm by 28mph indicated and stays there until variation occurs.
I'm not a huge believer in the accuracy of the "butt dyno" for detecting small changes in performance, but I don't own a motorcycle dyno. Initially, the bike "felt" slower due to the change in effective engine speed. For purpose of comparison, I went to my favorite intersection for a few acceleration tests. There are five lanes to cross, plus about 200ft from the intersection line to a 40mph speed limit sign. Historically, after a tune-up, I could launch from 3000rpm at this intersection and register 38mph on the speedometer as I pass the sign. Today, with the new rollers, I was able to make repeated runs from the stop line to the sign with a 3000rpm launch and see 42mph on the speedometer.
The one true observation I can propose is that the rollers have had an effect on how the transmission applies engine power. My hypothesis is that the launch at the torque peak has improved the bike's 0-30 performance. The change in registered speed at my target sign is improved by the fact that the bike is now doing 30mph by the time it crosses the intersection. I'm not a little guy (260lbs), so the performance change might be more dramatic for a lighter rider.
A secondary, less demonstrable observation that I've made is that it takes a bit less engine speed to maintain road speed and that minor changes in engine speed seem to have less of an effect on road speed. This was, IMO, a happy accident. On new Kymco rollers, I would register 6000rpm at 48mph, and an engine speed decrease of 100rpm would cause the indicated speed to fall to 45mph. With the 18gm sliders, I register 6000rpm and 52mph. Reducing the throttle by 100rpm does not result in an immediate loss of speed. When the speed does decrease, it does not drop in 3mph increments. Rather, I saw a gradual decrease in 1mph increments. I don't know how many of your Yager riders find the "fussy" throttle a bit annoying, but this once change in behavior might be worth the price of 18gm sliders alone if it's something that bothers you.
When I have some time, I'm taking the bike out the Interstate to see if there has been any change in top speed. With the old rollers, my cutoff speed (9250rpm) has fallen to 69mph, from a max of 72mph when just broken in. Hopefully, I can raise the max a touch closer to YagerGT200i's reported top speed.
In the interest of full disclosure, the bike is still running it's original belt. It's worn less than .5mm, so I'm not sure how much that will change things. I'm also on my original rear tire. It's worn by about half tread depth; again, I'm not sure how much of an impact it has on performance.
