fits model: Yfz450r. make: Yamaha. year: 2009–2012.

( Brand: Hot Cams ), ( Manufacturer Part Number: 8818-H482214-ATV ), ( Part Type: Valve )
The **CAMS 8818-H482214 Valve Shim Kit (9.48mm Valve Shim 2.55mm)** is a precision-engineered performance upgrade designed exclusively for the **2009 2012 Yamaha YFZ450R ATV**, offering a subtle yet impactful adjustment to enhance engine efficiency and throttle response. Engineered by **CAMS Performance**, a trusted name in high-performance valve train components, this shim kit is crafted from **high-grade, heat-treated steel** to ensure durability and consistent performance under demanding conditions. The **9.48mm valve shim** replaces the stock component, fine-tuning the valve lift and duration to optimize airflow through the cylinder head, which can lead to improved power delivery, smoother acceleration, and better high-RPM performance. With a **2.55mm thickness**, this shim strikes a balance between stock and aggressive tuning, allowing for a noticeable yet manageable increase in engine output without requiring extensive modifications to the rest of the valve train. Ideal for riders seeking a **cost-effective yet effective** way to dial in their YFZ450R s performance, this shim kit is compatible with the stock camshafts and requires no additional tuning or software adjustments, making it a straightforward upgrade for both novice and experienced ATV enthusiasts. Perfect for those looking to squeeze out extra horsepower and torque while maintaining reliability, the **CAMS 8818-H482214** is a simple yet effective solution for riders who demand more from their Yamaha YFZ450R without overhauling the entire engine.
### **Pros and Cons of buying a CAMS 8818-H482214 ATV Valve Shim (2.55mm for 2009 2012 Yamaha YFZ450R)**
#### **Pros:**1. **Improved Engine Performance** The correct valve shim ensures proper valve lift and timing, which can enhance engine efficiency, power delivery, and throttle response. A worn or incorrect shim may cause misfires, poor acceleration, or reduced horsepower.
2. **Prevents Engine Damage** Valve float (when valves don t close fully) can lead to catastrophic engine failure due to piston-to-valve contact. Replacing a worn shim prevents this risk.
3. **Authentic Fitment** The **2.55mm shim** is the correct specification for the **2009 2012 Yamaha YFZ450R**, ensuring compatibility without clearance issues.
4. **Cost-Effective Solution** Replacing a single valve shim is far cheaper than overhauling the entire valve train or repairing engine damage caused by valve float.
5. **Easy Installation** Valve shims are relatively straightforward to replace with basic hand tools, making this a DIY-friendly repair for those with mechanical experience.
6. **Increased Reliability** A properly adjusted valve train reduces excessive wear on camshaft lobes, pushrods, and rocker arms, extending the lifespan of these components.
7. **Available from Reputable Brands** **CAMS** is a well-known manufacturer of high-quality valve shims and engine parts, offering durability and precision machining.
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#### **Cons:**1. **Requires Valve Train Disassembly** To replace a valve shim, the engine s valve cover, rocker arms, and pushrods must be removed, which involves significant labor if done professionally.
2. **Potential for Mistakes** If the wrong shim size is installed (e.g., mixing up intake/exhaust or incorrect thickness), it can cause performance issues or damage. Double-checking measurements is critical.
3. **Time-Consuming for Beginners** While not extremely difficult, valve train work can be fiddly, especially for those unfamiliar with engine disassembly. Improper handling of components (e.g., bending pushrods) can complicate repairs.
4. **Additional Wear Indicators** If the shim replacement is due to wear, other parts (e.g., camshaft lobes, rocker arms) may also be worn and should be inspected. Ignoring this could lead to recurring issues.
5. **Cost of Professional Labor** If not comfortable with DIY, labor costs at a repair shop can add up, especially if multiple components need attention.
6. **Limited Lifespan of Other Components** If the engine has high mileage, other parts (e.g., spark plugs, fuel system, or piston rings) may also need attention, making this a symptom of broader engine aging.
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### **Conclusion:**Replacing the **CAMS 8818-H482214 2.55mm valve shim** on your **2009 2012 Yamaha YFZ450R** is a **necessary and beneficial repair** if symptoms like misfires, rough idle, or loss of power are present. The shim is a **critical wear item** that, when failed, can lead to severe engine damage. The **pros outweigh the cons** for most owners, as the fix is **relatively inexpensive, preventative, and performance-enhancing** when done correctly.
However, the **main drawback** is the **labor involved** either in terms of time for DIYers or cost for professional work. If you re experiencing **valve float symptoms**, delaying the repair risks **expensive engine damage**, so addressing it promptly is advisable.
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### **Recommendation:**1. **Verify Symptoms** Confirm that the issue is indeed a **worn valve shim** (e.g., check for excessive valve lash, misfires, or a "ticking" noise at high RPM). A **compression test** or **scanning for misfire codes** can help rule out other problems.
2. **Gather Tools & Parts**
- Purchase the **correct shim (2.55mm for your model)** from a trusted source (e.g., **CAMS, Yamaha parts, or a reputable aftermarket supplier**).
- Ensure you have **feeler gauges, a valve spring compressor, and basic hand tools** (sockets, wrenches, torque wrench).
- Consider **replacing other worn components** (e.g., rocker arms, pushrods) if they show signs of damage.
3. **DIY vs. Professional Repair**
- **If comfortable with engine work**, proceed as a DIY project. Follow **Yamaha service manuals** or **reliable online guides** (e.g., **ATV/UTV forums, YouTube tutorials**).
- **If unsure**, take it to a **Yamaha dealer or ATV specialist** to avoid mistakes. They can also inspect the **entire valve train** for hidden issues.
4. **Prevent Future Issues**
- **Check valve lash periodically** (every 500 1,000 hours or as recommended in the manual).
- **Use high-quality oil** to reduce wear on valve train components.
- **Monitor for early symptoms** (e.g., rough idle, hesitation) to catch shim wear before it causes failure.
5. **Budget for Potential Upgrades**
- If the engine has high mileage, consider **upgrading to aftermarket shims** (e.g., **CAMS or JE** for better durability) or **replacing rocker arms** if they are worn.
- If the **camshaft is worn**, a **camshaft replacement or upgrade** may be needed for long-term reliability.
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**Final Verdict:** **Buy and replace the shim ASAP if symptoms are present.** It s a **simple, cost-effective fix** that prevents **major engine damage**. If you re not confident in DIY repairs, **have a professional handle it** to ensure correctness. Regular maintenance will keep your **YFZ450R running smoothly** for years.
Brand: Hot Cams, model Number: 8818-H482214-ATV. I need to exchange an item. This is helpful if you are buying multiple items. 2009 - 2012 Yamaha YFZ450R SE.
Parts without fitment are to be assumed universal and may require vehicle modification. Hot Cams 9.48mm Valve Shim-2.55mm for 2009 - 2012 Yamaha YFZ450R ATV: Made from 4140 cold rolled steel, shim kits and refill packs make the perfect addition to any toolbox keeping valve train in working order.