another way to approach would be upgrade rotor to something larger and keep oem master cyl.
i use a XR400 clutch perch and lever on my bike w/ one of those car clamps that have the place for a mirror mount.
Originally Posted by ADV8
The 11mm RMZ 450 master cylinder works,no mirror boss and a pressure switch banjo bolt needed.
The stock DR650 clutch cable fits up to the RMZ clutch perch and lever also,quality parts and shorter levers unlike the bargain basement DR items.
This picture needs updating as it was before the pressure switch banjo bolt arrived