Cylinder studs locate and bolt the cylinder to the crank casing. Typically on an older scooter they can rust, but more commonly failure is caused by overtightening or cross-threading the end when the nuts are tightened.

Replacement is super easy, and will tidy the issue straight up. This Polini set replaces the factory set, and has a rust preventing finish for great longevity of use. It also comes with new nuts and brass washers, ready for install.