The integrated belt tension adjustment allows you easily adjust the tension of the belt depending on the wear rate of the belt. The integrated belt tension adjustment features multiple positions which are good enough for regular racing conditions. When the belt will be worn a lot you can still use the end position which is available in the area where the upper bulkhead mounts to the lower bulkhead.
The basic position for belt tension is the middle position.
After some racing time, the belt can bacame more free; therefore, the nylon hubs shold be moved into this position.
When the belt became old and position from the picture 2 does not make the belt tensioned enough, it is recommended to use one extra bulkhead position as shown on the picture 3.
Use the same procedure for the front and rear belt. For some extreme racing conditions optional externall belt tensioner set is available
Source : XRAY