PBI 321-15 Sprocket (Countershaft Steel 15T)

Works but with modifications to your holder. The original retainer that holds the sprocket on, goes over the teeth of the shaft, you rotate it in a groove to line up the screw holes on the sprocket and bolt it on. The offset from turning it makes the retainer no longer line up with the teeth on the shaft so it can't come off. This sprockets bolt pattern perfectly aligns with the teeth on the sprocket so you need to modify the sprocket retainer (Honda mb5) to be able to rotate so the teeth are not aligned and the sprocket won't just fall off

Bought this (16T) hoping it would lower my rpms and increase top speed. It lowered my rpms but on flat ground it never reached above 55mph. Probably be better on hills versus flat surface. Everything is stock on my grom besides this sprocket.

Looks well made. Fit and performed as described. My Grom accelerated a bit quicker and is more driveable around town. Nice, inexpensive upgrade.

Fit perfectly. Made riding higher speeds nice by bringing the rpms down

Fits right in there

Perfect