Braking System

Overall the braking system works well but there are some aspects which can be safely improved to enhance performance and tailor controls to the rider. These are outlined below.

Front Brake
The only real modification is to fit a 320mm disk but the only examples have been with machines fitted with YZ forks.
Rear Brake
The rear brake on the F650GS collects a large volume of dirt and muck from the road. This can result in grooving of the brake disc and increased wear of the pads and rear disc.

The brake is prone to overheating and brake fade in difficult terrain. After inspection of brake fluid and components brake professionals advised it is a result of the combination of low fluid volume and attachment of the steel brake hose to the rear of the engine.

The standard fluid line is very difficult to work on and remove due to the location and mounting of the junction between the rubber and steel brake lines behind the engine.

The solution is a larger reservoir coupled with a single piece braided stainless steel brake line between the caliper and the master cylinder. With this modification the fluid stays clear and brake fade is eliminated. A single piece line needs to be between 1.0 and 1.1 metres in length without the fittings, any excess in length loops up in front of the fuel tank.

Rear Brake
The BMW unit looks 10 to 15cc in capacity with side mounting. Replacements are available in 15, 30 and 45cc capacities with a choice of 0, 45, 90 degree hose fittings.
Brake Pedal
The existing brake pedal is too long for some people to use with aftermarket foot peg relocation systems and the after market brake pedals available do not suit all riders. The existing brake pedal can be modified to provide some adjustment in length and positioning as well as opening up the ability to fit folding tips.

Brake Pedal Modification

1/ Remove Brake Lever from machine

2/ Cut brake lever at second bend (cut 1)

3/ Cut rear weld of pedal tip (cut 2)

4/ Clean up cuts in both pieces with a file

5/ Drill holes in brake pedal as per diagram

6/ Drill holes in brake tip as per diagram

7/ Tap holes in brake tip with 5mm thread

GS650 Brake Pedal Diagram

8/ Bend Brake tip as per diagram

9/ Reweld rear end of serated tip

10/ Check and clean 5mm threads in tip

11/ Sand and repaint brake pedal

12/ Assemble pedal and tip, Refit to machine

Use 2 of 10mm x 5mm stainless steel allen
bolts to assemble the pedal and tip

The use of the 10mm hole spacing provides 4 positions of adjustment in lever length but more importantly you now have a pedal which you can replace the tip only or have longer or custom tips made to suit your boot size

Rear Brake Line Components and Construction

The brake line construction can vary with a banjo fitting at the caliper and either a hose end or banjo to connect to the master cylinder dependant on personal choice. The standard components are shown below