KAWASAKI 13027-036 Nos Piston 4TH O/s 1.00MM

( Manufacturer Part Number: 13027-036 ), ( Part Type: Piston )

Review KAWASAKI Nos 4th O/s 1.00mm Piston fits TRAIL BOSS G4 G5 1970–1972

The **Kawasaki 13027-036 NOS (New Old Stock) 4th Overhead Spring (O/S) 1.00mm Piston** is a meticulously preserved, high-performance component designed specifically for the legendary Kawasaki G4 and G5 Trail Boss models from the early 1970s. This particular piston, still encased in its original packaging and bearing the unopened, pristine condition of a piece never installed in a running engine, represents a rare opportunity for enthusiasts seeking to restore or upgrade their classic trail bikes to factory-spec or even beyond. Crafted from high-grade aluminum alloy, the **1.036-inch (1.00mm) diameter piston** is engineered to deliver optimal compression and combustion efficiency, ensuring reliable power delivery while maintaining the original engine s displacement and torque characteristics. The **4th overhead spring** designation indicates its compatibility with the Trail Boss s overhead valve (OHV) cylinder head design, where precise piston-to-ring clearance and ring gap are critical for smooth operation and longevity. Whether used in a meticulously restored 1970 or 1972 Trail Boss or as a replacement for a worn-out original, this NOS piston guarantees authenticity and performance without the compromises of aftermarket alternatives. Its inclusion in a well-maintained engine can significantly enhance throttle response, fuel economy, and overall mechanical integrity, making it an indispensable part for any serious collector or rider aiming to preserve the raw, unfiltered spirit of Kawasaki s trail-ready powerhouses from the golden era of off-road motorcycling.

### **Pros and Cons of Buying a Kawasaki 13027-036 NOS (4th O/S, 1.00mm Piston) 1970 G4/1972 G5 Trail Boss**

1. **Near-Original Condition (NOS)** The fact that this part is "New Old Stock" means it has not been previously installed or heavily used, reducing the risk of wear or damage from prior assembly. This is particularly valuable for restoration or high-mileage builds where reliability is critical.

2. **High-Quality Manufacturing** Kawasaki was (and still is) known for producing durable, well-engineered components. The 13027-036 is likely a genuine, factory-spec part designed for the G4/G5 Trail Boss engines, ensuring proper fitment and performance.

3. **Rarity and Collectibility** NOS parts for older Kawasaki models, especially from the early 1970s, are becoming increasingly difficult to find. Owning one may appeal to collectors or enthusiasts who value authenticity and historical significance.

4. **Potential for Performance** The 1.00mm piston upgrade (compared to stock) suggests a slight increase in compression ratio or displacement potential, which could improve power output if paired with the right cylinder, crankshaft, and tuning. However, this depends on the rest of the engine build.

5. **Compatibility with Classic Engines** The G4 (1970) and G5 (1972) Trail Boss engines share many common components, making this part versatile for both models. If you're working on a dual-engine project or a single engine with mixed parts, this could be a useful addition.

6. **Reduced Risk of Counterfeit Parts** Authentic NOS parts are less likely to be fakes or aftermarket knockoffs, which can be problematic with older Kawasaki models where counterfeitness is a concern.

7. **Potential for Resale Value** If preserved properly, a NOS Kawasaki part from this era could retain value, especially among serious collectors or restorers.

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1. **Age and Wear Potential** Despite being NOS, the part may still show signs of age, such as minor corrosion, dried-out gaskets, or slight wear on mating surfaces. It s important to inspect it thoroughly before installation.

2. **Limited Availability of Documentation** Kawasaki s documentation for older parts may be scarce or outdated. Without proper manuals or service bulletins, installation or troubleshooting could be challenging.

3. **Compatibility Issues** While the part is designed for the G4/G5 Trail Boss, subtle differences in later models or modified engines (e.g., different crankshafts, connecting rods, or cylinder bores) could cause fitment problems. Always verify measurements and clearances.

4. **Cost vs. Value** NOS parts can be expensive, especially for older models. If the part is only needed for a single project, the cost may outweigh the benefits compared to a rebuilt or remanufactured alternative.

5. **Maintenance and Preservation Needs** A NOS part requires careful storage to prevent rust or degradation. If not stored properly, it may arrive in poor condition despite being "new."

6. **Potential for Mixed-Batch Parts** Even NOS parts can sometimes come from mixed production batches, meaning they might not be exact duplicates of the original parts used in a specific engine. This could affect performance or longevity.

7. **Skill Required for Installation** Installing a piston in a Kawasaki engine, especially one from this era, requires mechanical expertise. Improper installation (e.g., incorrect oil clearance, improper gasket seating) can lead to catastrophic engine failure.

8. **Market Saturation** While NOS parts are rare, the demand for them is high. If you re not a serious collector or restorer, the price may be prohibitive compared to newer or aftermarket alternatives.

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- You are restoring or rebuilding a classic engine and prioritize authenticity.

- You have the mechanical skill and resources to properly install and maintain it.

- You are willing to pay a premium for a rare, high-quality part.

- The slight piston upgrade (1.00mm) aligns with your performance goals.

- You lack experience with older Kawasaki engines and need extensive guidance.

- The cost exceeds the value of the project or the part s potential resale.

- You can find a comparable rebuilt or aftermarket part at a lower price with similar reliability.

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1. **Inspect Thoroughly Before Purchase** Check for corrosion, wear, or damage. Request documentation or a history of the part if possible.

2. **Verify Compatibility** Ensure the piston fits your specific engine configuration (crankshaft, rod length, cylinder bore). Measure oil clearance and compression height.

3. **Consider Alternatives** If budget is a concern, explore rebuilt pistons from reputable manufacturers (e.g., JE, Scat, or Kawasaki s own remanufactured parts).

4. **Pair with Other NOS Components** If restoring, consider sourcing other NOS parts (e.g., crankshaft, cylinder, gaskets) for consistency.

5. **Budget for Installation** If you re not experienced, factor in labor costs or the time required to install it properly.

6. **Store Properly** If not using immediately, keep the part in a dry, corrosion-resistant environment.

**Final Verdict:** This is an excellent purchase for serious restorers or enthusiasts who value NOS components and have the expertise to handle them. For casual riders or those on a tight budget, a rebuilt or aftermarket piston may be a more practical choice.

Details:

NOS Kawasaki 4TH O/S 1.00mm Piston 1970 G4 1972 G5 Trail Boss 13027-036. Shipped with USPS Ground Advantage. Condition is New.

part #: 13027036 prices

• $37.99-$49.99

specifications bearingmotorcycleiz:

• for models: G4, G5, Trail, Boss
• for makes: Kawasaki
• for years: 1970-1972
• mpn: 13027-036
• part type: Piston

general bearingmotorcycleiz:

• Motorcycle Scooter Parts Accessories > Engines Engine Parts > Engine Bearings
• condition: New

offer bearingmotorcycleiz:

• quantity: 1
• availability: In Stock
• options: Ship-to-home
• sold: 0
• started: February 3, 2026

payments bearingmotorcycleiz:

• credit card: Diners-club
• other
• wallet: Apple-pay

seller bearingmotorcycleiz:

• # reviews: 2662
• rating: 100.0%
• city: Superior, Wisconsin

returns bearingmotorcycleiz:

• policy: Returns Accepted
• paid by: Buyer
• time: 14 Days

shipping bearingmotorcycleiz:

• class: Standard
• type: Calculated
• cost: $0.00
• transit: 4-10 Days
• service: USPS Ground Advantage
• carrier: USPS

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