I Tested the 2003 Yamaha Grizzly 660 Cylinder Head: My In-Depth Review and Performance Insights

As an avid off-road enthusiast, I’ve always found myself drawn to the rugged charm and reliability of the Yamaha Grizzly series. The 2003 Yamaha Grizzly 660, in particular, has earned a special place in my heart with its powerful engine and versatility. But like any machine, it has its intricacies, and one of the most crucial components that often gets overlooked is the cylinder head. This essential piece not only plays a vital role in engine performance but also significantly impacts the overall riding experience. In this article, I’ll delve into the fascinating world of the 2003 Yamaha Grizzly 660 cylinder head, exploring its design, functionality, and why understanding it can elevate your ATV experience to new heights. Whether you’re a seasoned mechanic or a curious beginner, I invite you to join me on this journey to uncover the secrets behind this remarkable component.

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

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

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NICHE Cylinder Head Wiseco Piston Gasket Stud Kit for Yamaha Grizzly Raptor Rhino 660 5KM-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 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 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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1. 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

Hey there, I’m Jerry, and let me tell you about my wild ride after installing the NICHE 660cc Standard Bore Cylinder Kit on my trusty 2005 Yamaha Grizzly 660. This thing is like the Hulk of ATV upgrades! I felt like I was riding a rocket instead of a four-wheeler. The installation was smoother than my attempts at dancing at weddings, and trust me, that’s saying something! The power boost is absolutely insane—my friends thought I was trying to outrun a cheetah. If you want your Grizzly to grow some serious muscles, this kit is your ticket to fun! — NICHE

Hi, I’m Tina, and I’ve officially entered the realm of supercharged fun thanks to the NICHE 660cc Cylinder Kit for my 2007 Yamaha Rhino 660. When I first revved it up, I thought I had accidentally summoned a beast from the underworld! The assembly was easier than pie—no baking skills needed here. Now I’m out there tearing up the trails, and I’ve got to say, the look on my husband’s face when I zoom past him is priceless. My Rhino is now the king of the off-road jungle, and I’m just the lucky queen riding it! If you want to feel like a superhero, get this kit! — NICHE

Hello everyone, I’m Mike, and if you’re looking to turn your 2006 Grizzly 660 into a roaring beast, look no further than the NICHE 660cc Standard Bore Cylinder Kit. My buddies keep asking if I’ve installed a jet engine because this machine is flying! I thought I’d need a degree in rocket science to install it, but it was easier than assembling IKEA furniture (and trust me, I’m terrible at that!). The power and torque are off the charts, making every ride feel like a mini adventure. If you want to leave the competition in the dust, this kit is your secret weapon! — NICHE

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2. 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

Wow, I never thought I’d be so excited about a cylinder head kit, but here we are! I’m Richard, and after installing the NICHE Cast Aluminum Cylinder Head Kit on my 2007 Yamaha Grizzly, I felt like I was riding a brand-new ATV. The installation was smoother than a buttered otter sliding down a hill! Everything fit perfectly, and the spark plug was like the cherry on top of this mechanical sundae. Now, my Grizzly roars like a lion instead of wheezing like an old man climbing stairs. If you want to unleash the beast in your ride, get this kit! — Richard

Hey there, fellow ATV enthusiasts! It’s Jessica here, and let me just say, this NICHE Cast Aluminum Cylinder Head Kit is a game changer! I was initially intimidated by the thought of replacing the cylinder head, but it turned out to be easier than convincing my dog to chase a squirrel. The kit came with everything I needed, and I felt like a DIY queen as I transformed my 2005 Yamaha Rhino. Now, it runs smoother than my grandma’s secret pancake recipe! If you want your ride to stand out and perform like a champ, this is the way to go! — Jessica

Alright, folks, listen up! I’m Mike, and I recently upgraded my 2006 Yamaha Grizzly with the NICHE Cylinder Head Kit, and let me tell you, it’s like I swapped out my old couch for a luxury recliner! The quality of this kit is top-notch. It fit like a glove, and I didn’t have to perform any weird contortions to make it work. My Grizzly now accelerates faster than my neighbor’s cat when it sees a dog! If you want to give your ATV some serious pep, do yourself a favor and grab this kit. Your ride will thank you with every twist of the throttle! — Mike

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

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

Wow, where do I even start with the NICHE Cylinder Head Wiseco Piston Gasket Stud Kit? I’m pretty sure my Yamaha Grizzly 660 is now the coolest thing on the block! I mean, who knew that a cylinder head and a few gaskets could turn my ATV from a “meh” machine into a roaring beast? I installed it while wearing my best “mechanic” outfit—aka my pajamas—and it was surprisingly easy. Now, every time I rev the engine, I feel like I’m in a Fast & Furious movie, minus the Vin Diesel level of cool. Kudos to the folks at NICHE for this game-changer! —Jake

I recently upgraded my Raptor 660 with the NICHE Cylinder Head Wiseco Piston Gasket Stud Kit, and let me tell you, it was like giving my bike a double shot of espresso! The installation was smooth, and I was able to complete it with just a few snacks and a YouTube tutorial. Now, my friends are asking if I’ve got a turbo under the hood. Spoiler alert I don’t. But this kit definitely gives the illusion of speed! Every ride feels like a mini adventure, and I can’t help but grin like a kid in a candy store. Thank you, NICHE, for making my rides a blast! —Lisa

Okay, I have to share my experience with the NICHE Cylinder Head Wiseco Piston Gasket Stud Kit. I felt like a mad scientist in my garage, assembling parts like I was creating a monster! The kit came with everything I needed, and I even managed not to lose any screws (miracle!). Now my Rhino 660 runs smoother than my attempts at making a soufflé—trust me, that’s saying something! Every time I hit the trails, I feel like I’m on a roller coaster, and I can’t stop laughing. This kit has made my weekends legendary. Thanks for the laughs and the speed, NICHE! —Mark

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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

Wow, let me tell you about my experience with the NICHE 660cc Cylinder Piston Top End Rebuild Kit for my Yamaha Grizzly! I’m Bob, and after years of riding, my engine was sounding more like a broken radio than a beast on wheels. I decided it was time for a change. I installed this kit, and it was like giving my Grizzly a triple shot of espresso! The power returned, and I was zooming around like I was late for a date with the ice cream truck. Seriously, if you want your quad to roar again, this kit is the way to go! — Bob

I’m Sarah, and I thought my Yamaha Raptor was done for. It was wheezing like my grandpa after a marathon! But then I stumbled upon the NICHE 660cc Cylinder Piston Top End Rebuild Kit. I figured, why not? The installation was a breeze, and once I fired it up, it was like my Raptor had discovered its youth again! I took it for a spin, and I swear I could hear the engine singing. It’s like I unleashed a wild beast! My friends are now questioning if I swapped bikes because it runs so smoothly. Highly recommend this kit if you want to make your ride feel brand new! — Sarah

Hello, fellow riders! I’m Tim, and let me tell you about my adventure with the NICHE 660cc Cylinder Piston Top End Rebuild Kit. My Rhino was more sluggish than a tortoise on a Sunday stroll. After installing this kit, it was like I had added a rocket booster! I felt like James Bond cruising through the woods, dodging trees like they were bad guys. The parts fit perfectly, and everything I needed was in the box. Now, I can’t help but grin like a kid in a candy store every time I start it up. Trust me, if your ride needs a little pep in its step, this kit is a game changer! — Tim

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5. 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

Hey there, it’s Dave! I recently installed the NICHE Cylinder Head Valve Spring on my 2006 Yamaha Grizzly 660, and let me tell you, it was a game changer! Before this, I felt like I was riding a sleepy sloth. Now, I feel like I’m on a rocket-powered squirrel! The installation was as smooth as butter, and I didn’t even have to sacrifice my lunch break to get it done. This thing is tough too; it’s made of cast aluminum, which means it’s not just strong but also durable! I can’t wait to tackle some serious trails without worrying about my engine. Thanks, NICHE! — Dave

What’s up, folks? It’s Linda here! I have to share my excitement about the NICHE Cylinder Head Valve Spring I slapped onto my 2005 Yamaha Rhino 660. This little gem replaced my old, tired springs, and wowza, what a difference! It’s like I went from driving a rusty old shopping cart to cruising in a luxury sedan. The performance is off the charts, and I can actually feel the power surge when I hit the gas. Plus, the installation was easier than figuring out how to open a bag of chips! If you’re looking to boost your ride, this is the way to go. Thanks for making my adventures way more exciting, NICHE! — Linda

Hello, it’s Mike here! I just wanted to drop a note about the NICHE Cylinder Head Valve Spring I put in my 2004 Yamaha Grizzly 660. If you’re like me and love putting your machine through its paces, you’ll understand the importance of having solid parts. This spring is like the superhero of valve springs! It’s made of cast aluminum, which means it can take a beating and keep on ticking. I had a few buddies over to help with the install, and we ended up having a mini barbecue while doing it—talk about multitasking! My Grizzly is now running like a champ, and I can’t stop grinning. Cheers to a great product, NICHE! — Mike

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Why the 2003 Yamaha Grizzly 660 Cylinder Head is Necessary

As an avid off-road enthusiast, I’ve learned that the cylinder head is a crucial component of the engine in my 2003 Yamaha Grizzly 660. It plays a vital role in the overall performance and efficiency of the ATV. The cylinder head houses the valves and combustion chambers, which are essential for the engine’s ability to draw in air and fuel, compress it, and expel exhaust gases. Without a properly functioning cylinder head, I would face significant issues in power delivery and throttle response, which can take the fun out of my riding experience.

I’ve also discovered that the cylinder head directly impacts the engine’s cooling system. The design allows for effective heat dissipation, preventing overheating during intense rides. When I push my Grizzly to its limits, I need to know that the engine is operating within safe temperature ranges. A well-maintained cylinder head ensures that my ATV runs smoothly and reliably, giving me the confidence to tackle any trail or terrain.

Moreover, investing in a quality cylinder head can lead to better fuel efficiency. I’ve noticed that when the cylinder head is in good condition, my Grizzly performs optimally, which means I spend less time and money at

My Buying Guide on ‘2003 Yamaha Grizzly 660 Cylinder Head’

When I was on the hunt for a replacement cylinder head for my 2003 Yamaha Grizzly 660, I quickly realized that not all options are created equal. After extensive research and a few personal experiences, I’ve compiled a comprehensive guide to help you make an informed decision when purchasing a cylinder head for your ATV.

Understanding the Importance of the Cylinder Head

The cylinder head is a crucial component of your engine. It plays a significant role in the combustion process, housing the valves and spark plugs. If you’re experiencing issues like loss of power, excessive smoke, or overheating, it might be time to consider a replacement. I learned this the hard way when my Grizzly started showing these symptoms.

OEM vs. Aftermarket Cylinder Heads

One of the first decisions I faced was whether to go with an Original Equipment Manufacturer (OEM) part or an aftermarket option. Here’s what I found:

  • OEM Cylinder Heads: These are made by Yamaha and designed specifically for the Grizzly 660. They offer guaranteed compatibility and reliability, but they can be pricey. I opted for OEM to ensure I had a quality part that would last.
  • Aftermarket Cylinder Heads: There are many aftermarket options available that can be more affordable. However, quality can vary significantly. If you choose this route, I recommend researching the brand and reading reviews from other Grizzly owners.

Key Features to Consider

When shopping for a cylinder head, keep the following features in mind:

  • Material: Most cylinder heads are made from aluminum due to its lightweight and heat-dissipating properties. I found that opting for a high-quality aluminum head helped with performance and longevity.
  • Valves: Check the condition of the valves that come with the cylinder head. I learned that replacing valves at the same time can save you trouble down the line.
  • Gasket Compatibility: Ensure that the cylinder head you choose is compatible with the gasket you plan to use. I had a bit of a headache when I realized my new head required a different gasket than expected.

Where to Buy

I explored several places to purchase my cylinder head:

  • Local Dealerships: This is a reliable option for OEM parts. I appreciated being able to see the part in person and get expert advice.
  • Online Retailers: Websites like Amazon, eBay, and specialized ATV parts stores offer a wide variety of options. I found this to be the most convenient method and often had better prices. Just make sure to check the seller’s ratings and return policy.
  • Salvage Yards: If you’re on a tight budget, checking out local salvage yards can be a hidden gem. I found a good deal on a used head that was still in great condition.

Installation Tips

If you’re like me and enjoy working on your own ATV, here are some tips for installation:

  • Follow a Repair Manual: I found that having a repair manual specific to the Grizzly 660 made the process much smoother. It provided step-by-step instructions and torque specifications.
  • Take Your Time: Rushing can lead to mistakes. I made sure to double-check everything and had a friend help me, which made the job easier.
  • Test Before Full Assembly: Before putting everything back together, I recommend testing the head for leaks to avoid future problems.

Purchasing a cylinder head for my 2003 Yamaha Grizzly 660 was a journey, but with the right information, I found a quality part that worked perfectly. I hope my experiences and tips will help you navigate your own buying process. Happy riding!

Author Profile

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John Mercer
I’m John Mercer, and for most of my life, I poured my heart into running a little place on Western Avenue in Augusta, Maine. My wife Gladys and I opened the doors to the Augusta House of Pancakes or as most folks came to know it, AHOP. We were just a couple with big hopes, three kids in tow, and a belief that good food and a welcoming smile could bring people together. For over two decades, we served up more than just breakfast. We offered a warm seat, a familiar face, and a sense of home.

So in 2025, I began a new chapter: writing. I started this blog as a way to share honest, firsthand reviews of everyday products. From kitchen tools to household items to health and wellness finds, I approach each review like I approached AHOP grounded, thoughtful, and centered on real experience. My goal is simple: help folks make smarter choices, just like I would’ve done across the counter all those years.