I have a 2007 Gsxr 1000 and i would be racing in CMRA. The rules state i can upgrade the master cylinder if it matches the same bore/stroke as oem.. Well the oem bore is 19mm.. Im wondering what the oem stroke is?

I am not familiar with CMRA rules, but that is a tricky one.

With WERA, MC's are a touchy subject and people have tried to change the stock MC on a Gixxer to a stock MC on something else (like an R1 for example, which comes with a Brembo MC stock) and have been shot down.