Changing Sprockets and Motorcycle Geometry
Changing the final drive sprockets not only affect acceleration and gear patterns, it'll alter your motorcycle's geometry in a massive way and could need remedying depending on how you ride. Adding a tooth (or two) onto the rear cog is a good, cheap, effective modification for trackdays.But it will also shorten wheelbase and boost the rear's ride height.
The general rule of thumb works on a 2:1 ratio (adding a tooth is usually 2mm extra ride height and vice versa) though every motorcycle is different with differing linkage ratios. You'll find the motorcycle will steer quicker and squat less on corner exit, but you may also find that rear-end grip is diminished slightly. If you like it, fine, but reducing tide height or even preload could be advisable after a session of testing.
Likewise, taking a tooth off the rear sprocket (or off the front) will lengthen wheelbase and reduce the ride height, which will make the steering lazier and the motorcycle harder work on acceleration. Although it might not sound like a big change on first impression, every millimeter counts when talking geometry.
That's why race teams will butcher brand-new chains, or even change the internal gear ratios just to keep the optimum wheelbase and the geometry settings these engender.
