Here is some clarification.
1. 904 - cylinders bored and sleeved,(depending on manufacturer)
2. 988 - cylinders bored/sleeved and crank stroked
3. 994 - purchase of new cylinders - cases bored only
4. 1087 - new cylinders, cases bored, crank stroked
5. 1100 - new cylinders, cases bored
6. 1200 - new cylinders, cases bored, crank stroked.
For the more extreme above you will need new rods, bearings, clutch and springs.
Link 1 Bonneville PerformanceLink 2 Triumph Performance USA