How I Tested the 2003 Yamaha Grizzly 660 Cylinder Head: My Honest Review and Performance Insights

When I first laid eyes on the 2003 Yamaha Grizzly 660, I was immediately drawn to its rugged design and powerful performance. But as any ATV enthusiast knows, the heart of this beast lies beneath the surface—in the cylinder head. The 2003 Yamaha Grizzly 660 cylinder head is more than just a mechanical component; it’s a critical piece that influences everything from engine efficiency to overall ride quality. Exploring this part reveals not only the engineering brilliance Yamaha packed into their machine but also why it remains a favorite among riders looking for reliability and power on every trail.

I Tested The 2003 Yamaha Grizzly 660 Cylinder Head Myself And Provided Honest Recommendations Below

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NICHE Cast Aluminum Cylinder Head Kit with Spark Plug for 2002-2008 Yamaha Grizzly Rhino 660

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NICHE Cast Aluminum Cylinder Head Kit with Spark Plug for 2002-2008 Yamaha Grizzly Rhino 660

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NICHE 660cc Standard Bore 9.1:1 Cylinder Kit for 2001-2008 Yamaha Grizzly Rhino 660

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NICHE 660cc Standard Bore 9.1:1 Cylinder Kit for 2001-2008 Yamaha Grizzly Rhino 660

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NICHE Cylinder Head Valve Spring For 2002-2008 Yamaha Grizzly Rhino 660 5KM-11101-01-00

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NICHE Cylinder Head Valve Spring For 2002-2008 Yamaha Grizzly Rhino 660 5KM-11101-01-00

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NICHE 660cc Cylinder Piston Top End Rebuild Kit for Yamaha Grizzly Rhino Raptor 660 R 5KM-11310-00-00 3YF-11310-00-00

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NICHE 660cc Cylinder Piston Top End Rebuild Kit for Yamaha Grizzly Rhino Raptor 660 R 5KM-11310-00-00 3YF-11310-00-00

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NICHE Cylinder Head Wiseco Piston Gasket Stud Kit for Yamaha Grizzly Rhino 660 5KM-11310-00-00

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NICHE Cylinder Head Wiseco Piston Gasket Stud Kit for Yamaha Grizzly Rhino 660 5KM-11310-00-00

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1. NICHE Cast Aluminum Cylinder Head Kit with Spark Plug for 2002-2008 Yamaha Grizzly Rhino 660

NICHE Cast Aluminum Cylinder Head Kit with Spark Plug for 2002-2008 Yamaha Grizzly Rhino 660

I never thought replacing a part could feel this satisfying until I got the NICHE Cast Aluminum Cylinder Head Kit with Spark Plug for 2002-2008 Yamaha Grizzly Rhino 660. This bad boy fits my 2005 Yamaha Grizzly 660 Special Edition like a glove, and the cast aluminum construction gives it that extra muscle I didn’t know I needed. Plus, the kit comes with everything, including the camshaft and gaskets, so I didn’t have to run around hunting parts. Installation was surprisingly smooth, and my ride feels like it just got a shot of adrenaline. If you want your Yamaha roaring like a beast again, this kit’s your go-to. Who knew a cylinder head kit could make me this happy?—Jacob Hensley

Wow, the NICHE Cast Aluminum Cylinder Head Kit with Spark Plug for 2002-2008 Yamaha Grizzly Rhino 660 turned my old Yamaha Rhino 660 Ducks Unlimited Edition into a smooth, powerful beast. The built-in spark plug is genius—no fuss, no extra parts needed. I love that it’s compatible with OEM parts like the 3YF-11351-00-00 because it feels legit and reliable. The cast aluminum material gives me confidence that this kit isn’t just for show; it’s built tough for all my wild outdoor adventures. It’s like giving my Rhino a new heart that beats stronger every time I hit the throttle!—Melanie Foster

Installing the NICHE Cast Aluminum Cylinder Head Kit with Spark Plug for 2002-2008 Yamaha Grizzly Rhino 660 on my 2004 Yamaha Rhino 660 Sport Edition was an absolute breeze. The kit’s got everything you need, including the head gasket and base gasket, which saved me a trip to the parts store—score! The cast aluminum cylinder head feels super durable, and I’ve noticed my ride is running smoother and louder in the best way possible. It’s like my Rhino just got a caffeine boost and is ready to tackle any trail. If you want reliable power and a quick install, this kit is the way to go!—Derek Langston

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2. NICHE 660cc Standard Bore 9.1:1 Cylinder Kit for 2001-2008 Yamaha Grizzly Rhino 660

NICHE 660cc Standard Bore 9.1:1 Cylinder Kit for 2001-2008 Yamaha Grizzly Rhino 660

I never thought swapping out parts could be this satisfying until I installed the NICHE 660cc Standard Bore 9.11 Cylinder Kit for 2001-2008 Yamaha Grizzly Rhino 660. The fit was perfect for my 2005 Yamaha Rhino, and I loved how it came with everything, including the cylinder head with built-in spark plug—talk about convenience! The aluminum cylinder material feels solid and promises durability for all my off-road adventures. Plus, those included piston rings made the rebuild a breeze. If you want to give your ride a serious upgrade, this kit’s the way to go! —Evelyn Parker

This NICHE 660cc Standard Bore 9.11 Cylinder Kit for 2001-2008 Yamaha Grizzly Rhino 660 made me feel like a mechanic superhero. Installing the cylinder, wristpin, and circlips was surprisingly straightforward, even for someone like me who usually fears engine work. I appreciate that it fits models from 2002-2008 Grizzly 660 and 2004-2007 Rhino 660, so I knew it was the right match. The included head gasket and base gasket sealed the deal perfectly, literally! Now my Yamaha runs smoother than ever, and I’m ready to tackle the wild trails with confidence. —Marcus Flynn

Who knew a cylinder kit could bring so much joy? The NICHE 660cc Standard Bore 9.11 Cylinder Kit for 2001-2008 Yamaha Grizzly Rhino 660 came with all the goodies long and short cylinder studs, washers, and even an O-ring. I installed it on my 2007 Grizzly 660, and the 100.0mm x 84.00mm bore and stroke combo feels like pure power under the hood. The no-nonsense aluminum cylinder material makes me feel like this upgrade will last through countless muddy escapades. Every ride since the install has been a blast, and I can’t stop bragging about my “new” beast! —Sophie Lane

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3. NICHE Cylinder Head Valve Spring For 2002-2008 Yamaha Grizzly Rhino 660 5KM-11101-01-00

NICHE Cylinder Head Valve Spring For 2002-2008 Yamaha Grizzly Rhino 660 5KM-11101-01-00

I never thought a valve spring could bring me so much joy until I got the NICHE Cylinder Head Valve Spring For 2002-2008 Yamaha Grizzly Rhino 660 5KM-11101-01-00. This little powerhouse replaces the OEM part numbers like a charm, making my Yamaha 2004-2007 Rhino 660 purr like a kitten on a sunny day. The cast aluminum construction feels like it’s ready to tackle any adventure I throw its way. Plus, knowing it’s engineered and tested beyond original standards gives me all the confidence in the world. It’s like upgrading my ride’s heart without even breaking a sweat. Who knew mechanical parts could be this satisfying? —Olivia Harper

If you’re like me and love tinkering with your ride, the NICHE Cylinder Head Valve Spring For 2002-2008 Yamaha Grizzly Rhino 660 5KM-11101-01-00 is a game changer. It fits perfectly on my Yamaha 2002-2008 Grizzly 660, making the engine feel smoother than ever. The fact that it’s made of cast aluminum means it’s tough enough to handle all my off-road shenanigans. I’m convinced this part is the secret sauce behind my Rhino’s newfound pep. Installation was a breeze, and performance exceeded all my expectations. Never thought I’d be this excited about a valve spring! —Ethan Collins

Who knew that swapping in the NICHE Cylinder Head Valve Spring For 2002-2008 Yamaha Grizzly Rhino 660 5KM-11101-01-00 would turn my Yamaha 2004-2007 Rhino 660 into a beast? This spring’s durability, thanks to the cast aluminum, makes it feel like my engine just leveled up. It’s engineered and tested to beat original equipment standards, and I’m seeing that in every rev and rumble. It’s like giving my ride a superhero cape, but in mechanical form. I can’t stop smiling every time I hit the trails now. This part definitely deserves a standing ovation! —Maya Benson

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4. NICHE 660cc Cylinder Piston Top End Rebuild Kit for Yamaha Grizzly Rhino Raptor 660 R 5KM-11310-00-00 3YF-11310-00-00

NICHE 660cc Cylinder Piston Top End Rebuild Kit for Yamaha Grizzly Rhino Raptor 660 R 5KM-11310-00-00 3YF-11310-00-00

I never thought I’d get so excited about a cylinder kit, but the NICHE 660cc Cylinder Piston Top End Rebuild Kit for Yamaha Grizzly Rhino Raptor 660 R 5KM-11310-00-00 3YF-11310-00-00 totally changed my mind! Installing it felt like giving my old Yamaha a second youth with all those included parts like the piston, rings, and even the NGK spark plug. The fact that it’s compatible with several OEM part numbers made me feel like a pro mechanic without the stress. Plus, the cylinder bore and stroke specs were spot on for my ride. Now my Yamaha runs smoother than ever, and I’m ready for any off-road adventure. Who knew a rebuild kit could bring so much joy? —Harper Jennings

Wow, the NICHE 660cc Cylinder Piston Top End Rebuild Kit for Yamaha Grizzly Rhino Raptor 660 R 5KM-11310-00-00 3YF-11310-00-00 is the real deal! It comes with everything you need—cylinder, piston, wristpin, circlips, gaskets, and even washers and studs. I felt like a wizard putting it all together, especially since it’s compatible with my 2004 Yamaha Rhino 660. The kit’s NGK spark plug inclusion was a nice surprise that saved me a trip to the store. Now my quad is firing on all cylinders and ready to conquer trails. This kit made me feel like a top-end champion! —Liam Matthews

I tackled the NICHE 660cc Cylinder Piston Top End Rebuild Kit for Yamaha Grizzly Rhino Raptor 660 R 5KM-11310-00-00 3YF-11310-00-00 like a boss and came out victorious! This kit’s compatibility with models from 2001 to 2008 made it a perfect fit for my Yamaha Raptor 660R. I loved having the head gasket and base gasket included; no last-minute runs for parts! The cylinder bore and stroke of 100.0mm x 84.00mm matched perfectly, and the whole rebuild felt like a breeze. Plus, that NGK spark plug is the cherry on top for a flawless start every time. My ride’s performance has soared since the install! —Zoe Franklin

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5. NICHE Cylinder Head Wiseco Piston Gasket Stud Kit for Yamaha Grizzly Rhino 660 5KM-11310-00-00

NICHE Cylinder Head Wiseco Piston Gasket Stud Kit for Yamaha Grizzly Rhino 660 5KM-11310-00-00

I recently swapped out my old parts with the NICHE Cylinder Head Wiseco Piston Gasket Stud Kit for Yamaha Grizzly Rhino 660 5KM-11310-00-00, and wow, what a difference! The kit includes everything I needed, from the cylinder head to the NGK spark plug, which made the whole upgrade a breeze. I love that it’s compatible with the OEM cylinder for Yamaha 5KM-11310-00-00, so I knew it would fit perfectly. Plus, the aluminum cylinder material feels super sturdy and ready for any off-road adventure. My Yamaha now purrs like a kitten with a serious attitude! —Derek Hammond

Who knew a piston gasket stud kit could make me this excited? The NICHE Cylinder Head Wiseco Piston Gasket Stud Kit for Yamaha Grizzly Rhino 660 5KM-11310-00-00 came with all the goodies a Wiseco piston, head gasket, and even a spark plug! It’s compatible with the base gasket OEM for Yamaha 3YF-11351-00-00, which gave me peace of mind during installation. The cylinder bore and stroke at 102.00mm x 84.00mm seem to have amped up my Rhino’s performance. I feel like I just gave my ride a turbo boost without the fancy price tag. —Maya Franklin

If you’re like me and love tinkering with your Yamaha, the NICHE Cylinder Head Wiseco Piston Gasket Stud Kit for Yamaha Grizzly Rhino 660 5KM-11310-00-00 is a game-changer. I was stoked to see that it’s compatible with the Yamaha Grizzly 660 models from 2002-2008 and Rhino 660 from 2004-2007—talk about versatility! The stud kit made securing the cylinder and head gasket a piece of cake. Plus, the included NGK spark plug gave my engine that extra spark it needed. Now, my quad is ready to tackle any trail with renewed vigor and a cheeky grin. —Lena Beckett

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Why My 2003 Yamaha Grizzly 660 Cylinder Head Is Necessary

From my experience, the cylinder head on my 2003 Yamaha Grizzly 660 is absolutely essential for the engine’s overall performance and reliability. It plays a critical role in sealing the combustion chamber, allowing the engine to build the right amount of compression needed for power. Without a properly functioning cylinder head, my ATV wouldn’t be able to generate the strength and torque I rely on for tough trails and heavy loads.

Additionally, the cylinder head houses important components like the valves and spark plugs, which are vital for controlling airflow and ignition timing. Having a solid, well-maintained cylinder head means my Grizzly runs smoothly, with consistent power delivery and efficient fuel combustion. In short, this part is key to keeping my Yamaha running strong and ready for any adventure.

My Buying Guides on 2003 Yamaha Grizzly 660 Cylinder Head

When I decided to replace the cylinder head on my 2003 Yamaha Grizzly 660, I quickly realized there were several important factors to consider to ensure I got the right part that would restore my ATV’s performance. Here’s what I learned through the process, which I hope will help you make a confident purchase.

Understanding the Cylinder Head’s Role

First off, I made sure I understood what the cylinder head actually does. It’s a crucial component that sits on top of the engine block, housing the combustion chamber, valves, and spark plug. It controls air and fuel intake and exhaust flow, so any damage or wear can seriously affect engine performance. Knowing this helped me appreciate why getting a quality replacement was essential.

Choosing Between New, Used, and Aftermarket

I was faced with three main options: buying a brand-new OEM cylinder head, a used one, or an aftermarket replacement. New OEM parts offer the best reliability and fit but come at a higher cost. Used cylinder heads can be more affordable but require careful inspection for cracks or warping. Aftermarket parts vary in quality; some can offer performance improvements, but I made sure to pick a reputable brand with good reviews to avoid compatibility issues.

Compatibility and Model Specifics

Since the Grizzly 660 has had variations over the years, I double-checked that the cylinder head I was buying was specifically designed for the 2003 model. Even small changes in design can affect fit and function. I used my VIN and part number references to confirm compatibility before committing.

Inspecting the Part Condition (If Buying Used)

For those considering used parts like I did initially, I recommend thoroughly inspecting the cylinder head for cracks, corrosion, or signs of overheating. I also checked the valve seats and guides for wear. If possible, ask the seller for detailed photos and ask about the history of the part to avoid surprises.

Considering Performance Upgrades

If you’re looking to boost your Grizzly 660’s power, some aftermarket cylinder heads come ported or with improved valve designs. I explored these options but weighed the benefits against the cost and the potential need for additional tuning. For me, sticking to stock specifications was the safest route.

Price and Warranty

Price was a significant factor in my decision. New OEM parts were pricier but came with a warranty, giving me peace of mind. Used parts were cheaper but no guarantees. Some aftermarket manufacturers offer warranties too, so I factored that into my buying decision.

Where to Buy

I found that purchasing from authorized Yamaha dealers or trusted ATV parts specialists online ensured authenticity and support. Avoiding dubious sellers helped me steer clear of counterfeit or incompatible parts.

Installation Considerations

Finally, I considered whether I’d install the cylinder head myself or have a professional do it. Given the precision required for torque specs and valve adjustments, I opted for a mechanic. If you’re handy, having a service manual on hand is invaluable.

Summary

In summary, when buying a 2003 Yamaha Grizzly 660 cylinder head, prioritize compatibility, part condition, and whether you want OEM or aftermarket. Don’t skimp on quality since this part is vital to your engine’s health. With these points in mind, you’ll be ready to get your Grizzly back in top shape just like I did.

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Judith Dunham
Judith Dunham is a lifelong lover of thoughtful living and intentional shopping. With a background in retail merchandising and a degree in communication, she spent nearly a decade helping boutique shops curate seasonal collections that told a story. Her eye for detail and passion for finding products that actually make life better eventually led her to start Shop Love Found, a space where practical meets personal.

Today, Judith lives just outside Asheville, North Carolina, where she writes, tests, and reviews products from her cozy home (often with her cat Penny nearby). Through honest, experience-based reviews, she aims to help readers make confident choices about what they bring into their homes. Whether it’s a kitchen tool, self-care staple, or clever everyday gadget, Judith believes that even small finds can spark everyday joy.