KYB 25 mm XR Bladder Upgrade Kit Dal Soggio

The Dal Soggio 1P.XR-KIT-KYBD25 XR Kit is a front suspension upgrade developed specifically for KYB forks equipped with a 25 mm diameter rebound piston.

The XR system converts the compatible KYB cartridge to Dal Soggio’s bladder-based pressure compensation architecture, combining the bladder conversion with specific valving developed for the system.

The purpose of the conversion is to improve the way the fork reacts to changes in internal pressure and hydraulic movement. According to Dal Soggio, the XR bladder system is designed to make the front fork more sensitive and compliant while providing improved rider feedback across different riding speeds.

Unlike the WP XACT CC version of the XR Kit, the KYB 25 mm version does not feature the rapid spring preload adjustment system. Spring preload therefore remains dependent on the standard suspension configuration and setup procedure.

The XR Kit is designed as a retrofit solution for the original KYB suspension, allowing the fork to be upgraded without replacing the complete front suspension assembly.

Dal Soggio manufactures the XR components using high-quality aeronautical aluminum alloys with hard-anodized surface treatments, providing the mechanical durability required for demanding off-road suspension use.

Correct identification of the rebound piston diameter is essential before installation: SKU 1P.XR-KIT-KYBD25 is intended specifically for KYB forks using the 25 mm rebound piston configuration.

Key Features

• Developed specifically for KYB front forks equipped with a 25 mm diameter rebound piston
• Bladder-based conversion system with dedicated Dal Soggio valving included
• Designed to increase initial fork sensitivity, compliance, and rider feedback
• Manufactured using aeronautical aluminum alloys with hard-anodized components
• KYB D25 version is supplied without the rapid spring preload adjustment system

Technical Specifications

Application & Compatibility

The 1P.XR-KIT-KYBD25 is compatible only with KYB fork configurations using a 25 mm rebound piston.

Dal Soggio officially lists the following motorcycle applications:

• Fantic XXF 250 – 2021 to 2024
• Fantic XXF 450 – 2021 to 2024
• Yamaha YZ250F – 2019 to 2024
• Yamaha YZ450F – 2018 to 2022

Compatibility depends on the internal KYB cartridge specification rather than simply the motorcycle brand or fork external diameter.

For this reason, the 25 mm rebound piston diameter should always be confirmed before ordering or installation, especially where forks may previously have been modified, replaced, or internally updated.

How the XR Kit Works

The XR Kit replaces part of the original cartridge pressure-management arrangement with a bladder system.

As the suspension compresses and rebounds, the bladder accommodates variations in oil volume and internal pressure. This architecture is intended to allow the hydraulic system to react more freely and progressively to suspension movement.

Dal Soggio combines the bladder conversion with specific internal valving, so the system is designed to operate as a complete hydraulic package rather than as a standalone bladder replacement.

The intended benefits include:

• improved initial sensitivity;
• smoother response over small impacts;
• improved front-wheel feedback;
• more progressive hydraulic behavior;
• consistent suspension response over varying speeds and terrain.

No Rapid Preload System

This particular KYB D25 XR Kit does not include Dal Soggio’s rapid preload adjustment system.

This is an important distinction from the WP XACT CC version of the XR Kit, which uses an externally adjustable preload mechanism.

Spring preload on the KYB D25 application must therefore be managed according to the original fork architecture and the suspension technician’s setup procedure.

Installation Note

Installation requires opening and servicing the fork cartridge, fitting the XR components, setting the supplied valving correctly, refilling the suspension with the appropriate oil, and accurately bleeding the hydraulic system.

For this reason, installation and final setup by a qualified suspension technician or Dal Soggio specialist are recommended.

Before installation, always verify that the fork uses the required 25 mm rebound piston, as the XR range also includes a separate version for KYB forks with a 24 mm rebound piston.