DSC Club Member
 BSB Star
 Bikes: 2009 Ducati Monster 1100s, KTM 890R
     Posts: 5,996
 Join Date: May 2003
 Location: Coulsdon, Surrey...........and hopefully Germany at some point in the future.
 Mood: I love the Monster and the KTM & I have my wife exactly where she wants me!
  
    
     If you are still using a four piston caliper then the original master cylinder should be ok, you will of course benefit by fitting a later more up to date master cylinder.
 
 The only time you really have to change the master cylinder is when you change from a two piston caliper to a four piston type, then you need the extra capacity/ratio of a master cylinder suited to a four piston caliper.
 
 As a point of interest, I chnaged the original 2 piston calipers on my Jota to four piston Brembo`s and fitter AP Lockheed ajustable ratio master cylinders which I can only praise in terms of performance and quality of construction.