The 1978 Kawasaki KD 125 is a classic dual-sport motorcycle that many enthusiasts still ride and restore. One of the most critical systems to maintain or upgrade is the suspension. Properly functioning suspension not only improves ride quality but also safety and handling. Whether you are rebuilding a barn find or refreshing a daily rider, knowing which suspension parts fit and where to source them is essential. This guide covers everything from front forks and rear shocks to bushings and springs, helping you make informed decisions for your restoration.
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OHLINS SUSPENSION SHOCK for Kawasaki Z125 Pro
Overview of the 1978 KD125 Suspension System
The KD125 came with a conventional telescopic fork up front and twin shock absorbers at the rear. The suspension design was typical for its era—simple, serviceable, and durable. The front fork uses 31mm tubes, and the rear shocks have a specific length and spring rate tuned for the lightweight bike. The linkage system (swingarm and related bearings) is straightforward but can wear out over time.
Front Forks
The front fork on the 1978 KD125 is a non-adjustable, damped telescopic unit. Key components include:
- Fork tubes (stanchions): 31mm diameter, chrome-plated steel. They are prone to pitting or bending if the bike was crashed.
- Fork sliders (lower legs): Cast aluminum, often with corrosion.
- Fork seals: Standard 31mm seals that prevent oil leakage.
- Fork springs: Progressive or linear rate springs that support the front end.
- Damping rods: Control compression and rebound damping.
Common issues include leaking seals, worn bushings, and sagging springs. Rebuilding the fork is straightforward with basic tools and a race seal driver.
Rear Shocks
The stock rear shocks are non-rebuildable oil-damped units with coil springs. They are specific to the 1978 KD125 and can be hard to find in new condition. Aftermarket options exist, but they must match the 320mm eye-to-eye length and appropriate spring rate for the bike's weight (around 200 lbs fully loaded).
Common problems: loss of damping, spring sag, and corrosion of the shock body. Replacing with quality aftermarket shocks is often the best route for improved ride quality.
Linkage Bearings and Bushings
The swingarm pivots on two bearings (bronze bushings or needle bearings) that wear out. The KD125 uses sealed bearings in the swingarm and linkage. If you feel play in the rear end, it's likely the pivot bearings. Additionally, the rear shock mounts have rubber bushings that harden with age.
Common Issues and Replacement Options
Aftermarket vs. OEM
- OEM parts: Kawasaki still offers some suspension components for the KD125 through its parts network. However, availability is limited. OEM parts like fork seals and bushings are reliable but can be pricey.
- Aftermarket parts: Companies like All Balls Racing, Race Tech, and Progressive Suspension offer fork seals, springs, and complete shock upgrades. For the rear, consider replacement shocks from brands like YSS or Ikon. These are often better than stock and more readily available.
Interchangeable Parts from Other Models
The 1978 KD125 shares its 31mm fork with several Kawasaki models of the same era, such as the KE125 and some KX125 variants. Check parts lists for these models—often fork seals, bushings, and springs are identical. The rear shock mounting pattern is more unique, but you can adapt shocks from other bikes if length and eye size match. Always measure before purchasing.
Restoration Tips
Rebuilding Forks
- Remove the fork legs from the triple clamps.
- Drain old fork oil (typically 10W, but 15W for firmer damping).
- Disassemble using a socket to push the damping rod lock nut.
- Inspect tubes for corrosion or bends. Replace if damaged.
- Replace seals, dust wipers, and bushings.
- Refill with fresh oil to the correct level (usually 130-150mm from top with spring out).
- Reassemble and torque the top cap to spec.
Choosing Correct Springs
Stock springs are soft (0.40 kg/mm). For heavier riders or aggressive use, consider aftermarket progressive springs (e.g., Race Tech). Verify free length—if sagged more than 25% of original, replace. For budget builds, using springs from a donor KDX200 may work with minor adjustments.
Rear Shock Replacement
If you cannot find OEM, look for aftermarket shocks with 320mm length and 10mm eyelet hardware. Set preload for your weight. Many modern shocks have adjustable damping, which greatly improves comfort.
Final Recommendation
For a 1978 Kawasaki KD125 restoration, start with the front forks: replace seals, bushings, and oil. For the rear, replace the shocks with aftermarket units designed for the bike's specs. Check all pivot bearings and replace if any play exists. Use OEM parts when possible for critical safety items like fork springs, but aftermarket upgrades can enhance performance. If you are unsure, consult a local motorcycle suspension specialist or vintage bike forum. A well-sorted suspension transforms the KD125 into a fun, reliable classic trail bike.