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  2. sku: 17566732428720871
  3. YAMAHA B3J-21101-10-00

YAMAHA B3J-21101-10-00 Frame Chassis Engine Cradle

fits model: Yz450fx, 450f, Yz. make: Yamaha. year: 2020.

B3j-21101-10-00 Yamaha 2020 Yz450fx Main Frame Chassis Engine Cradle Yz 450f Oem

( Manufacturer Part Number: B3J-21101-10-00 ), ( Type: Cradle ), ( Country Of Origin: Japan )

Review YAMAHA Main Frame Chassis Engine Cradle Oem fits YZ450FX 450F YZ 2020

The **Yamaha YZ450FX (2020 model) Frame, Chassis, and Engine Cradle Assembly (Part Number: B3J-21101-10-00)** represents the backbone of one of the most revered off-road motorcycles in the world a machine designed to dominate trails, motocross tracks, and endurance races with precision and durability. Crafted from high-grade materials and engineered with Yamaha s signature attention to detail, this frame and chassis assembly embodies a perfect blend of lightweight strength and structural rigidity, ensuring optimal power transfer and rider confidence in the harshest conditions. The **YZ450FX s frame** is a masterclass in modern motocross design, featuring a **double-cradle construction** that not only enhances rigidity for superior handling but also optimizes weight distribution to keep the bike agile and responsive. The **engine cradle**, an integral component of this assembly, is forged from robust steel and meticulously integrated with the frame to minimize flex and vibration, allowing the rider to channel every ounce of power from the 449cc, liquid-cooled, single-cylinder engine into the trail or track with minimal energy loss.

At the heart of this assembly lies Yamaha s legendary **449cc parallel-twin engine**, though in the context of the frame and chassis, its influence is felt through the precise mounting and alignment systems that ensure the powerplant remains perfectly balanced within the cradle. The **engine cradle itself** is a study in functionality, featuring reinforced mounting points, precise alignment guides, and a design that accommodates both the stock and aftermarket components seamlessly. Whether you're a factory racing team looking to rebuild a championship-winning YZ450FX or a dedicated off-road enthusiast seeking to restore a classic, this frame and cradle assembly provides the ideal foundation for a bike that demands respect. The **2020 iteration** of this assembly incorporates subtle refinements in material selection and manufacturing processes, ensuring enhanced durability and a longer lifespan even under the most demanding conditions.

For those who appreciate the art of motocross engineering, this frame and chassis assembly is not just a collection of parts it s a testament to Yamaha s commitment to innovation and performance. The **YZ450FX s frame** is engineered to absorb impacts while maintaining structural integrity, a critical feature for riders pushing the limits of speed and control. The **engine cradle**, in particular, is designed to work in tandem with the frame, ensuring that the bike s power delivery remains consistent whether you're carving through tight corners or launching off jumps. This assembly is a perfect choice for both stock builds and custom projects, offering the strength and precision needed to transform a raw YZ450FX into a machine capable of winning races or conquering the most challenging trails. Whether you're a mechanic, a racer, or a passionate rider, this frame and cradle assembly is a cornerstone of Yamaha s legendary off-road heritage.

### **Pros and Cons of Buying a 2020 Yamaha YZ450FX Frame/Chassis/Engine Cradle (from a YZ450F)**

#### **Pros**

1. **High-Quality Build** Yamaha s YZ450F is renowned for its durable and well-engineered frame, chassis, and engine cradle. The materials used (aluminum alloy, reinforced steel, and precision machining) ensure longevity and reliability, even when sourced separately.

2. **Proven Performance** The YZ450F s engine cradle and frame are designed for high-performance motocross, offering a balance of power, responsiveness, and durability. The 450cc parallel-twin engine is known for its smooth power delivery and reliability, making it a favorite among riders.

3. **Compatibility with Other Parts** Since this is a direct transfer from a YZ450F, it will fit seamlessly with other Yamaha YZ450F components (e.g., suspension, brakes, wheels, and aftermarket upgrades). This makes it easier to build a custom bike if desired.

4. **Resale Value** Yamaha s reputation for durability means that even used frames and cradles hold value well, especially if they come from a well-maintained YZ450F.

5. **Lightweight Design** The frame and cradle are engineered to be as light as possible without sacrificing strength, improving handling and maneuverability key advantages in motocross.

6. **Minimal Rust Concerns** Yamaha bikes are generally less prone to rust compared to some Japanese competitors, though proper storage and maintenance are still essential.

7. **Aftermarket Support** The YZ450F has a strong aftermarket following, meaning you ll find plenty of upgrades (e.g., suspension, exhaust, and engine modifications) to further enhance performance.

8. **Reliability for Racing or Freeride** If you re building a bike for racing, freeride, or heavy-duty riding, the YZ450F s frame and engine cradle are robust enough to handle abuse.

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#### **Cons**

1. **Age of the Unit (2020 Model)** While 2020 is relatively recent, the bike may have seen some wear if it was used for aggressive riding. A thorough inspection (especially for cracks, bent frames, or engine cradle damage) is crucial before purchasing.

2. **Potential for Hidden Damage** If the frame or cradle was in an accident (even a minor one), structural integrity could be compromised. A professional inspection is recommended to rule out hidden issues.

3. **No Warranty** Since this is a used part (even if from a YZ450F), there will be no manufacturer warranty. You ll need to trust the seller s history and condition reports.

4. **Cost vs. New Parts** Buying a used frame or cradle may be cheaper than purchasing a new one, but if you re building a bike from scratch, you might find better deals on complete bikes or newer parts.

5. **Compatibility with Non-Yamaha Parts** While the YZ450F shares similarities with other 450cc bikes (e.g., KTM, Husqvarna), some aftermarket parts may not fit perfectly without modifications.

6. **Storage and Transport Challenges** A frame and cradle alone are heavy and bulky, requiring proper storage and transport solutions. If you re not experienced with bike assembly, this could be a logistical hassle.

7. **Potential for Outdated Technology** The YZ450F (even in 2020) is not the latest model, meaning some features (e.g., electronic suspension, advanced ECU tuning) may not be available compared to newer bikes.

8. **Risk of Seller s Discrepancies** Without a full inspection, there s a chance the frame or cradle may have been modified improperly or may not match the description (e.g., bent frame, cracked welds).

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### **Conclusion**

Buying a **2020 Yamaha YZ450FX frame, chassis, and engine cradle** from a YZ450F is a solid choice if you re looking for a **durable, high-performance foundation** for a custom motocross bike. The pros such as Yamaha s reputation for quality, compatibility with aftermarket parts, and proven reliability make it an attractive option for serious riders. However, the cons including the lack of warranty, potential hidden damage, and the need for careful inspection mean you must approach this purchase with caution.

If you re **building a bike from scratch** and can afford the time and effort to inspect and assemble it properly, this could be a **cost-effective way to get a strong platform**. If you re unsure about the condition or lack experience with bike builds, it may be better to consider a **complete used YZ450F** or a **new frame from a reputable dealer**.

### **Recommendation**

- **If you re experienced and can inspect thoroughly:** Proceed with confidence, especially if the price is significantly lower than a new frame. Prioritize a **full mechanical inspection** (frame for cracks, cradle for weld integrity, engine for wear).

- **If you re unsure about condition or assembly:** Consider buying a **complete used YZ450F** or a **new frame from Yamaha s parts department** to avoid risks.

- **If budget allows:** Look for a **newer model (2021 )** if available, as they may include slight refinements in design or materials.

Ultimately, this purchase is best suited for **riders who value durability, performance, and customization** but only if they take the necessary precautions to ensure they re getting a sound part.

Details:

I can provide a bill of sale on request, and notarize it if requested. No significant damage noted. In good shape. I can not guarantee the age, quality or longevity of these used wear parts.

The exact item you see in the photographs is same are receiving. Has typical wear and tear. The same applies to any bearings/seals/gaskets. I always recommend when buying a suspension, motor or brake component to inspect and replace any wear parts if deemed necessary.

Some parts, especially electronics, may be shipped with deliberate paint markings or security stickers. If you are looking for expedited shipping, or combined contact me PRIOR to purchase the easiest buying experience. These parts likely fit many different years/ model's. I also have a video of the bike starting and running for assurance as well.

If you re unsure of fitment, message me with your make model and year I may be able to help point you in the right direction. Please review all posted photos carefully. All parts were personally removed from a good running 2022 Yamaha YZ450FX with 136 hours on it according to the CCU. 2020 Yamaha YZ450FX.

Inspect and replace if necessary. Items come as pictured. Previous owner stated he could not locate the title, believes it is in his house somewhere, so unfortunately ai do currently have paperwork for frame. I am more than happy to send you specific pictures upon request.

I rode the bike for about 2 hours and was able to ensure all systems on were in good working order.

part #: b3j211011000 price

  • $929.99

specifications mocycfra:

  • for models: Yz450fx, 450f, Yz
  • for makes: Yamaha
  • for years: 2020
  • mpn: B3j-21101-10-00
  • type: Cradle
  • country of origin: Japan

shipping mocycfra:

  • carrier: UPS
  • class: Economy
  • cost: $70.61
  • service: UPS Ground Saver
  • type: Calculated
  • transit: 3-8 Days

seller mocycfra:

  • # reviews: 975
  • city: Pottsville, Pennsylvania
  • rating: 99.9%

general mocycfra:

  • Motorcycle Scooter Parts Accessories > Body Frame > Frames Parts
  • condition: Used

returns mocycfra:

  • policy: No Returns

payments mocycfra:

  • credit card: Discover
  • wallet: Apple-pay
  • other

offer mocycfra:

  • sold: 0
  • options: Ship-to-home
  • started: April 6, 2026
  • quantity: 1
  • availability: In Stock
for models: yz450fx, 450f, yz, for makes: yamaha, for years: 2020, type: cradle, country of origin: japan,
category: motorcycle parts > motorcycle scooter parts accessories > body frame > frames parts, sku: 17566732428720871,
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  • Used. Offer #1 priced at $929.99 + $0.00 shipping estimate = $929.99* total. Clean and ready to go! Removed From: 2020 Yamaha YZ250FX.FREE SHIPPING

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