Production Cup is currently 250/400/500

If 250 bikes are phased out of prod cup scoring, no longer a stand alone 250 class
1. Allow unlimited engine modifications to increase the bore and stroke to no greater than the new prod cup classification 400/500, 350/500.

This will allow those that have 250's to continue to campaign them, against the bigger CC bikes. This is a cheaper solution to trying to sell the 250 to another club and build a new prod racer.