Variable Ratio Type - CP4125-26

Variable Ratio Type - CP4125-26

This unique design of pull type handlebar master cylinder provides the user with the ability to adjust the ratio and the lever position as required.
The single chamber configuration allows the compact design to weigh only 320grams, and is now non handed to allow it to be used as a clutch master cylinder. This master cylinder is used by top GP and Superbike teams. Use with remote fluid reservoir (not supplied)

- Single chamber configuration.
- Incremantal ratio adjustments, Ratio is 6.88 - 14.45:1.
- Adjustable lever position.
- Reverse for use as clutch master cylinder.
- Use with remote fluid reservoir. (not supplied)

Typical Applications:

- Moto GP, Superbikes & Road.

Assembly Part Numbers:
- CP4125-26 (17mm to 20mm effective bore).

Ratio Adjustments Guide.
This variable ratio master cylinder has a knulled wheel to adjust the ratio. This adjuster is rotated to increase or decrease the lever ratio.

Technical Specifications & Notes.
- Master Cylinder will be supplied with the wheel adjuster set at position 0 ( i.e. with the fulcrum point at end of guide slot in lever, nearest to end of the handlebars, as drawn) at this setting piston travel is at its maximum, which will give best conditions for bleeding the brake system. Typical working stroke is shown as a guide only, working stroke should be set to riders preference. After initial setting only small adjustments, typically ±1 turn should be necessary to suit differing conditions. The ratio adjuster wheel has a detent mechanism allowing it to be moved ¼ turn per click. No locking of the mechanism is required. Lever travel will usually increase slightly in dynamic applications over static settings due to disc run-out etc. it is therefore advisable to set lever feel on the hard side for initial test.
- Master Cylinder will be supplied with the lever reach set at the nominal position as drawn. To obtain a longer reach the adjuster should be turned anti-clockwise using the reach adjuster wheel to suit riders preference. Conversely the adjuster can be turned clockwise to give a shorter reach. Adjustments should be made in ¼ turn increments, but should not be set between detents positions. The correct lever reach should be established prior to any adjustment to the lever ratio using the wheel adjuster.
- Outlet fitting is not supplied with assembly as standard, but Tecalamit or Aeroquip are available on request.
- To remove lever sub-assembly, take the Master Cylinder off the handlebar, then set wheel adjuster in position 0. Knock out spring and remove the lever reach adjuster wheel. Turn the exposed pull rod clockwise using the 1mm slot in it’s end until the lever assembly is disconnected from the pull rod lever sub-assembly will then slide out from the retaining flanges. To replace lever sub-assembly reverse the above procedure.

- Important: If any impact is sustained on lever causing a high pressure input to brake system, whole system should be replaced.
  • Effective bore size range - CP4125-26 (17mm to 20mm effective bore).
    Actual Bore Size - CP4125-26 - 22mm (0.86").
    Hydraulic Threads Outlet - M10x1.0
    Weight Kg 0.3
    Bleed Screw Tightening Torque 5.5Nm (4lbs/ft)
    Repair Kit - CP4125-26 = CP4125-26RK
  • Click on the link to download the relevant drawing.

  • Additional Information

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