| A ball bearing housed in a rubber insulator. Mounted to the upper side of the vehicle and used to support the driveshaft when more than one driveshaft is used. | |
| A shaft with eccentric lobes that controls the opening of the intake exhaust valves. | |
| A friction reducing bearing that uses a series of steel balls held between inner and outer bearing races, such as in a roller clutch. | |
| Passage or opening in a four stroke cylinder head for the exhaust valve. |