Can I upgrade Kawasaki ER-5's brakes?

Q. I want to replace my 1998 Kawasaki ER-5’s front brake caliper with a better brake, maybe a twin or a four-piston set-up.

Is there a brake that would fit straight on or would I have to make an adapter plate? Would I need to upgrade the master cylinder as well?
Al Gibbs, MCN forums
 
A. It’s certainly possible, and if you could find an exact match of part numbers between your bike’s disc and fork leg from Kawasaki’s range it would probably bolt straight on.

Otherwise you will have to make up an adapter plate and it would make sense to use a matched master cylinder because of the leverage ratio.

But if you do uprate the brake to that extent you may find that it overpowers the unadjustable suspension on your bike.

It’s always worth bleeding the brakes before you do anything else, in case an injection of new fluid could sharpen things up a bit.