Replacement 16 mm shock shaft for the original Soqi/Soki rear shock fitted to 1978–1982 Yamaha YZ125, YZ250 and YZ465 models. This shaft converts the original 14 mm Yamaha shock shaft arrangement to a 16 mm shaft and uses an internal rebound adjustment system based on the Öhlins 05500-series shock shaft design.

The conversion was developed to provide a practical replacement for worn or damaged original shock shafts while also using serviceable rebound needle, jet and pushrod components. The internal dimensions are based around commonly used Öhlins 05500-series components, making future servicing and tuning considerably more straightforward than relying on obsolete original Soqi/Soki parts.The shaft comes with a 3.2 open needle and jet.

Shock Shaft Specifications

• Application: 1978–1982 Yamaha YZ125, YZ250 and YZ465
• Original shock manufacturer: Soqi / Soki
• Conversion: 14 mm OEM shaft to 16 mm shaft
• Overall shaft length: 316 mm
• Shaft outside diameter: 16 mm
• Piston bore: 12 mm
• Piston-end thread: M12 x 1.25 mm
• Supplied with shock shaft internals

Öhlins 05500-Series Rebound System

The rebound needle and shaft jet arrangement is based on the Öhlins 05500-series ST46 / STX46 shock shaft system. The shaft is designed to accept the corresponding Öhlins-style rebound adjustment components listed below, including 05665 / 05666-series components and 05621-series open shaft jets.

A 5 mm OD rebound pushrod can be used. A pushrod longer than approximately 270 mm can be trimmed to the required finished length during assembly.

3.2 mm Rebound Needle and Jet Components

• Rebound needle: Öhlins 05665-04
• Teknik equivalent rebound needle: 26-062-03
• Needle O-ring: Öhlins 00338-14
• Open shaft jet: Öhlins 05621-04
• Teknik equivalent open shaft jet: 26-062-02
• No-bleed block-off jet: Öhlins 05665-00
• 0.5 mm bleed: Öhlins 05665-05
• 0.8 mm bleed: Öhlins 05665-08
• 1.0 mm bleed: Öhlins 05665-10
• 1.2 mm bleed: Öhlins 05665-12
• 1.4 mm bleed: Öhlins 05665-14
• 1.6 mm bleed: Öhlins 05665-16
• 1.8 mm bleed: Öhlins 05665-18
• 2.0 mm bleed: Öhlins 05665-20
• 2.2 mm bleed: Öhlins 05665-22

4.0 mm Rebound Needle and Jet Components

• Rebound needle: Öhlins 05665-03
• Teknik equivalent rebound needle: 26-062-01
• Needle O-ring: Öhlins 00338-14
• Open shaft jet: Öhlins 05621-03
• Teknik equivalent open shaft jet: 26-062-00
• No-bleed block-off jet: Öhlins 05666-00
• 0.5 mm bleed: Öhlins 05666-05
• 0.8 mm bleed: Öhlins 05666-08
• 1.0 mm bleed: Öhlins 05666-10
• 1.2 mm bleed: Öhlins 05666-12
• 1.4 mm bleed: Öhlins 05666-14
• 1.6 mm bleed: Öhlins 05666-16
• 1.8 mm bleed: Öhlins 05666-18
• 2.0 mm bleed: Öhlins 05666-20
• 2.2 mm bleed: Öhlins 05666-22

Important Note on Öhlins Jet Numbering

The Öhlins open shaft jet part numbers can appear to be the wrong way around when compared with their nominal sizes. This is intentional and the following numbers are correct:

• 05621-03 = 4.0 mm
• 05621-04 = 3.2 mm

The numbering reflects the order in which the components were developed rather than the jet diameter. The 4.0 mm version existed before the later 3.2 mm version, so the part-number suffix should not be interpreted as the jet size.

Installation and Setup

This is a specialist suspension rebuild and conversion component rather than a direct OEM replacement part. Correct assembly requires measurement of the original shock, selection of the appropriate rebound needle and jet combination, trimming of the rebound pushrod where required, and normal shock rebuilding procedures.

Confirm the dimensions and configuration of the original Soqi/Soki shock before installation, particularly where the shock may have been modified during its service life.