It is easy to change gear on a Rotax DD2. Just remove the transmission cover carefully not destroying the gasket. The gears are located under the cover, you can just lift the gears up and replacing them with new gear.
The total numer of teeth on a Rotax DD2 should be 97 teeth to fit together.
Gear ratio 1:st gear Rotax DD2
| Primary | Secondary | Ratio | Traditional Gear | Top speed at 12500 rpm |
| 32 | 65 | 8,65 | 10-87 | 75 km/h |
| 33 | 64 | 8,26 | 11-91 | 79 km/h |
| 34 | 63 | 7,89 | 11-87 | 83 km/h |
| 35 | 62 | 7,55 | 12-90 | 86 km/h |
| 36 | 61 | 7,22 | 12-87 | 90 km/h |
| 37 | 60 | 6,91 | 12-83 | 94 km/h |
| 38 | 59 | 6,61 | 12-80 | 99 km/h |
Gear ratio 2:nd gear Rotax DD2
| Primary | Secondary | Ratio | Traditional Gear | Top speed at 12500 rpm |
| 32 | 65 | 6,52 | 14-91 | 100 km/h |
| 33 | 64 | 6,23 | 14-87 | 105 km/h |
| 34 | 63 | 5,95 | 14-83 | 110 km/h |
| 35 | 62 | 5,69 | 14-79 | 115 km/h |
| 36 | 61 | 5,44 | 14-76 | 120 km/h |
| 37 | 60 | 5,21 | 14-73 | 94 km/h |
| 38 | 59 | 4,98 | 15-75 | 131 km/h |