Len Performance Front Track (Center) Shock, Polaris RMK Khaos AXYS & Matryx 2019–2026 (54-50004F)
Len Performance Front Track (Center) Shock, Polaris RMK Khaos AXYS & Matryx 2019–2026 (54-50004F)
Len Performance
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Product details
Len Performance LS4-50004F rebuildable front track shock, also called the center shock, for the rear suspension on the Polaris 850 RMK Khaos 155 / 163 / 165 (AXYS, 2019–2021) and the 2022–2026 Matryx RMK Khaos and Khaos Slash 146 / 155 / 163 / 165 in 650, 850, Patriot 9R and Patriot Boost. It replaces the factory front track shock with a coil-over reservoir shock. At $557.95 each, it is A2D's value pick for a rebuildable, adjustable reservoir front track shock: clicker adjustment, a reservoir and a serviceable design without the cost of a race-level shock.
The front track shock controls how the skid loads under acceleration, how the front of the track carries weight on sidehills and how much ski pressure you keep when you get on the throttle. This shock has separate low-speed and high-speed compression clickers (8 low / 3 high, per Len Performance) and a threaded body with locking preload rings, so it can be set for rider weight and snow conditions instead of running fixed factory valving.
Fitment. Sold each. Pairs with the Len Performance 54-50004R rear track shock for a complete rear suspension (Len Performance sells the pair as kit LS4-50004K). Matching ski shock: 54-50004. Chassis: Polaris AXYS (2019–2021 Khaos) and Matryx (2022–2026).
Fitment list (Len Performance year/model lookup)
- RMK / Khaos: 2019-2026 850 RMK Khaos 155; 2019-2022 850 RMK Khaos 163/165; 2019-2026 850 RMK Khaos 165; 2022-2026 650 RMK Khaos Slash 146 Matryx; 2022-2024 850 RMK Khaos Slash 146; 2022-2024 850 RMK Khaos Slash 155; 2022-2024 850 RMK Khaos Slash 163/165; 2022-2026 Patriot Boost RMK Khaos Matryx 155; 2022-2024 Patriot Boost RMK Khaos Slash 155; 2023-2026 Patriot 9R RMK Khaos 146 Matryx; 2023-2026 Patriot 9R RMK Khaos 155 Matryx; 2023-2026 Patriot 9R RMK Khaos 165 Matryx; 2023-2024 Patriot 9R RMK Khaos Slash 146; 2023-2024 Patriot 9R RMK Khaos Slash 155; 2023-2024 Patriot 9R RMK Khaos Slash 163/165; 2023-2024 Patriot Boost RMK Khaos Slash 163/165; 2025-2026 850 RMK Khaos 146; 2025-2026 Patriot 9R RMK Khaos 155 LE; 2025-2026 Patriot Boost RMK Khaos 165; 2026 Patriot Boost RMK Khaos 155 LE
Features
- Separate low-speed and high-speed compression clickers: 8-click low-speed and 3-click high-speed compression adjustment (per Len Performance).
- Aluminum reservoir shock: the remote-style reservoir keeps oil temperature down and damping consistent on long pulls.
- Fully rebuildable, serviceable shock. Len Performance rebuild kits and replacement parts are available.
- Hardened chromoly shaft for strength and seal life.
- Forged aluminum eyelet heads with premium steel and NBR bushings.
- Powder-coated spring resists corrosion and holds rate in cold, wet conditions.
- Threaded shock body with anodized dual-ring locking preload adjusters: set sag once and it stays set.
- Sold each.
Specifications
| Part number | 54-50004F (Len Performance LS4-50004F) |
| OEM part number replaced | 7045531 (per distributor listings) |
| Shock location | Front track shock / center shock (rear suspension) |
| Chassis / platform | Polaris AXYS / Matryx |
| Adjustments | Compression (8 low-speed / 3 high-speed), plus threaded spring preload |
| Length, extended | 306 mm / 12.05 in |
| Length, compressed | 213 mm / 8.39 in |
| Stroke | 93 mm / 3.66 in |
| Spring | Powder-coated coil spring included, 72 mm / 2.84 in diameter |
| Top eyelet | 20.5 mm ID x 21.8 mm wide (0.81 in x 0.86 in) |
| Bottom eyelet | 18 mm ID x 29.5 mm wide (0.71 in x 1.17 in) |
| Weight | 4.45 lb |
| Includes | One shock |
| Rebuild kit | Len Performance rebuild kits available; call to confirm the kit number for this shock |
| Sold | Each |
Ordering and installation. Sold each. Ships from stock at our Anchorage shop, or from our distributor's Boise, Idaho warehouse when not on the shelf. In-store pickup is available at checkout. Installation and shock setup are available at A2D Motorsports; call (907) 306-3062 to schedule. Len Performance rebuild kits are available, so the shock can be serviced or re-valved rather than replaced.