What Is ICBM™ Technology? A New Future for Vintage Engines

To Everyone Who Loves Engines

Hello, everyone. I'm Sotaro Inoue from Inoue Boring. I want to thank you all for your continued interest and support for what we do.

In this new series, I’m going to tell you all about ICBM™ technology—a project we at Inoue Boring have developed with great passion over many years. I want to explain it to you myself, with all the detail it deserves.

The engine. What does that word mean to you? Is it just a piece of machinery? I don't think so. For people like us, an engine is much more. We're all captivated by its unique pulse, its smell, and its functional beauty. This is especially true for the engines in vintage motorcycles. They have a timeless appeal, and it almost feels like they hold the spirit of their designers and the memories of the roads they’ve traveled.

As I often write in our company’s Japanese newsletter, the 20th century was the “century of the engine.” Engines expanded our world and changed everything. But now, in the 21st century, things are different. With a growing focus on environmental issues and the shift toward electric power, some people question the future of the internal combustion engine.

That's exactly why we feel so strongly about our mission: We want to preserve the amazing culture of engines for future generations. And we don’t just want to save them; we want more people to enjoy them in peak condition for many years to come. Our ICBM™ technology is how we are making that happen.

ICBM™ is more than just a repair method. It’s our way of giving new life to the engines we love, especially the hearts of vintage motorcycles. It’s our solution to ensure they continue to perform brilliantly, both today and for years to come. This technology is our commitment.

In this first article, I’ll explain what ICBM™ is, how we developed it, and what it makes possible. This might get a little long, but as a fellow engine lover, I hope you’ll follow along to the end.

The Story Behind ICBM™ Technology: Honoring Cast Iron While Pushing Beyond Its Limits

To understand why we created ICBM™, we have to look back. For much of the 20th century, most engine cylinders relied on cast iron sleeves, or liners. Cast iron offered a great balance of strength, machinability, and cost. It was also very compatible with piston rings, making it the standard choice for engine cylinders for many years. As engine specialists, we have the greatest respect for this material. The history of how engineers mastered cast iron to improve engine performance is truly impressive.

But demands on engines are always changing. People wanted more power, better fuel economy, and longer life. As these demands grew, some of the limitations of cast iron sleeves became clear.

Weight: Because it’s iron, it's heavy. This could sometimes hinder performance.

Wear: Friction from the piston rings would eventually wear the cylinder down. This led to a loss of performance and defined the engine’s lifespan. The constant need for overhauls was a direct result of this wear.

Heat Dissipation: Cast iron doesn't transfer heat very well. This could lead to power loss from heat soak or even overheating, especially in high-performance and air-cooled engines.

Rust: Being iron, rust was unavoidable. If an engine sat for a long time, the cylinder walls could rust, causing damage upon the next startup. This was a serious headache for vintage motorcycle owners, whose bikes are often carefully stored.

Inoue Boring has been in the business of reconditioning cylinders—or boring—since just after World War II. Working with worn and damaged cylinders every day, we understood the limits of cast iron better than anyone. We kept thinking, "Even if we bore a cylinder to fix it, it will just wear out again. Isn't there a way to make a cylinder that fundamentally resists wear?" That question stayed with me, and it became a part of our company’s DNA.

Then, in the 1990s, manufacturers like Honda began producing more all-aluminum cylinders without cast iron sleeves, using a plated bore instead. We had opportunities to work on these new cylinders and saw firsthand that the plating—mostly a nickel-silicon carbide coating—was incredibly hard and far more resistant to wear than cast iron. It was a natural next step for us to ask, "Could we apply this plating technology to older engines with cast iron sleeves?"

But the road wasn't easy. We were able to partner with a high-tech plating company that worked on advanced projects like those for Honda, but we immediately hit a major wall: productivity. The plating process was designed for mass production, where costs are manageable. How could we adapt it for the small batches we needed?

We had countless meetings with the plating company, trying to build a system for producing high-quality results on a small scale. Honestly, we ran into so many problems. More than once, I thought, "Maybe this is impossible." But we couldn't give up. I kept thinking, "What happens to the future of these engines if we stop? We can’t let down the owners who are waiting to get their vintage bikes back on the road." With that as our motivation, we gritted our teeth and kept pushing forward.

Finally, in 2016, after twelve long years of development, we perfected a technology that we could proudly offer to the world. That technology is ICBM™, which stands for Inoue Boring Cylinder Bore Finishing Method. The name carries our pride at Inoue Boring, and it also expresses our strong belief that this is not just a repair. It's an evolution—a way to "Bore up" the cylinder liner to a new level. It was an unforgettable moment for us, when all those years of hard work finally paid off.

Timeline of ICBM™ development:

20th Century: Cast iron sleeves were the standard for engine cylinders, offering strength but facing issues like weight, wear, heat dissipation, and rust.

Post-WWII: Inoue Boring began reconditioning engine cylinders, recognizing the limitations of cast iron.

1990s: Inoue Boring saw the potential of plating technology used in aluminum cylinders and sought to apply it to older engines.

2000s: Partnered with a plating company but faced challenges adapting for small-scale production.

2016: After 12 years of development, Inoue Boring perfected ICBM™, revolutionizing cylinder technology for vintage motorcycles.

The Plated Aluminum Sleeve and Its Benefits: Seven Advantages That Will Change How You Think About Engines

So, what exactly is the "plated aluminum sleeve" at the heart of our ICBM™ technology?

Simply put, it's a precision sleeve made from an aluminum alloy that is highly compatible with the cylinder block material (which is also usually an aluminum alloy). We then apply a special coating (a nickel-silicon carbide composite plating) to the inner wall—the surface the piston slides against. The basic approach of ICBM™ is to replace the original cast iron sleeve with this new one. For engines with a sleeveless, all-aluminum design, we apply the plating directly to the bore itself. (We select the best method for each engine’s specific structure.)

You might be thinking, "Can just changing the sleeve material really make that much of a difference?" Yes, it does. It changes things so much that it can turn your understanding of engines upside down. Here are the seven main benefits that our ICBM™ plated aluminum sleeves deliver:

1. Incredible Wear Resistance: This is the biggest feature of ICBM™. The plated surface is more than ten times harder than cast iron (more on this in the next article!). As a result, the cylinder shows almost no wear. Your engine’s initial performance is maintained for an incredibly long time.

2. Lightweight: Aluminum weighs about a third as much as iron. Making the engine lighter, especially around the cylinder, greatly improves the motorcycle’s handling.

3. Low Friction: The plated surface is extremely smooth. This reduces internal engine resistance, which improves throttle response and gives the engine a quick, light revving character. It also reduces wear even further.

4. Resistant to Seizure: Even under high temperatures and heavy loads, the sleeve has a natural resistance to piston seizure. In the event of a problem, damage to the engine is kept to a minimum.

5.Superior Heat Dissipation: Aluminum is a great conductor of heat. It efficiently draws heat away from the engine’s core, preventing power loss from heat soak and protecting against overheating. This leads to more stable performance.

6. Uniform Thermal Expansion: The aluminum block and the aluminum sleeve expand at nearly the same rate when heated. This means clearances remain stable as the engine warms up, creating a strong, unified bond between the cylinder and the sleeve.

7. And… It Doesn’t Rust! This is surprisingly important, especially for vintage motorcycles that are often ridden less frequently or put into long-term storage. A cast iron sleeve can start to rust on its inner walls with just a little moisture. When you next start the engine, that rust can act like sandpaper, scratching the piston rings and cylinder walls. That’s truly bad for an engine. With a plated aluminum sleeve, you have zero worries about that. For one of our newsletter features, we took a finished EverSleeve and submerged it in a saltwater tide pool for a photo, and it was completely unharmed. We are certain that this "rust-proof" quality alone will solve one of the biggest concerns for vintage bike owners.

These benefits don't just stand alone; they work together, raising the engine's overall performance, reliability, and lifespan to a level beyond what was previously possible.

We wanted to make this incredible ICBM™ technology available to more people and more shops. That led us to develop a finished, ready-to-install plated aluminum sleeve: the EverSleeve™ (patented in Japan). Each EverSleeve™ is a standalone unit that we precision-plate and hone right here at Inoue Boring. We designed it so that engine builders and bike shops everywhere can use it to create a high-precision plated aluminum cylinder with relative ease. We hope the EverSleeve™ makes our ICBM™ technology more accessible to everyone.

Why ICBM™ Technology Is "Revolutionary": A Bridge to the Future of Motorcycling

There's a reason we call ICBM™ technology a "revolution," not just an "improvement." We believe this technology does more than just enhance engine performance. It holds the power to change the future of vintage motorcycle culture itself and even reshape our relationship with engines.

First, it’s a technology that turns "giving up" into "hope." Have you ever looked at an engine and thought, "There are no more parts, it can't be fixed," or "It's too worn out, this engine is done"? ICBM™ can bring those very engines back to life. Even a completely worn-out cylinder can regain better-than-new performance and durability with our process. Every time we see classic machines like the Kawasaki Z, Honda CB, Yamaha RZ, or Suzuki Gamma return to their former glory and run strong again, it renews our pride and joy in this work. We feel that we are connecting something precious from the past to the future.

Second, it’s a technology that improves an engine's "total performance." The seven benefits I listed earlier—wear resistance, light weight, low friction, seizure resistance, heat dissipation, uniform expansion, and rust prevention—all work together. The result is that the engine isn't just better in one specific area. Its total performance, including power, response, durability, reliability, and ease of use, is elevated to a completely different level. This means that even engines with older designs can be ridden with confidence and enjoyed to the fullest on today's roads.

Third, it embodies our company's mission: "Making the world smile with engines!" At Inoue Boring, this is our slogan. We believe that when an engine is healthy, the bike is healthy. When the bike is healthy, the owner smiles. And that smile spreads to the people around them. ICBM™ technology is the tool that makes this possible. It is filled with our desire to make as many people as possible smile, all through the heart of their motorcycle: the engine.

Fourth, it’s a technology that is creating the "standard of the future." Today, almost all new high-performance motorcycles use plated aluminum cylinders. There's a simple reason for this: the technology is superior. ICBM™ makes that same superior technology available for engines built in the past. We see this not as just extending the life of a legacy product, but as presenting the "way things should be" for all engines—a new standard for the future. We've reached a point where, besides cost, there's almost no reason left to continue using heavy cast iron sleeves that wear out and rust.

As you can see, ICBM™ is not just the name of a part or a process. It is the result of our technology and our passion, born from a deep love for engines and a sense of responsibility for their future. That is why we proudly call this technology "revolutionary."

Our Conclusion: A Passion for Engines and a Promise for the Future

In this first article, I’ve shared the story of ICBM™ technology: what it is, how it was created, the ideas behind it, and the reasons why we use the word "revolution" to describe it.

ICBM™ technology uses the power of aluminum and a special plating process to overcome the challenges of cast iron sleeves. It gives an engine seven key advantages: 1. incredible wear resistance, 2. lighter weight, 3. low friction, 4. resistance to seizure, 5. superior heat dissipation, 6. uniform thermal expansion, and 7. a rust-proof design.

This is our promise and our practical solution for dramatically improving the performance and lifespan of the engines you love. It's how we can carry the wonderful culture of vintage motorcycles into the future. It is my sincere hope that through this technology, your life with motorcycles will be richer, longer, and filled with more smiles.

In our next article, we will take a closer look at the single most important benefit of ICBM™: its incredible wear resistance. We’ll answer the questions, "Why does it barely wear down?" and "How different is it really from cast iron?" I will share all the details behind its surprising durability and the true value this brings to your engine. For everyone who cares deeply about their engine, this is information you won’t want to miss. Please look forward to the next article.

Thank you very much for sticking with me through my passionate discussion today.

Sotaro Inoue 

CEO, Inoue Boring Co., Ltd.