[H2 Cylinder Manufacturing Using a 3D Printer]

November 5 – December 11, 2024

Text & Photos: Sotaro Inoue (President of iB) + Tomonari Nibe (M.C.C.)

Creating a cylinder from nothing but 3D data using a metal 3D printer—
We’ve truly entered an era where this is possible.

Ten years ago, this would have sounded like a dream. When resin 3D printers first appeared, we speculated, "One day, metal might be possible too!" And now, that day has arrived.
Without the need for casting molds or mass production, we can create a single cylinder with greater precision and strength than cast metal.

This time, iB had the opportunity to manufacture a Kawasaki Triple Mach 750cc (H2) cylinder. In fact, we previously machined H2 cylinders from solid aluminum blocks and successfully sold them. We were able to repurpose the 3D data from that project for this new 3D printing challenge.

At JIMTOF 2024 (Japan International Machine Tool Fair) held at Tokyo Big Sight in November, we exhibited the cylinder at the booth of DOHO, a non-ferrous metal trading company and importer of 3D printers.
The 3D printer showcased was the ZRapid, currently the world's best-selling metal 3D printer.

Thanks to the cooperation of Speed One, a Mach-specialized shop in Sakado, we were able to display not only the cylinder but also a fully assembled H2 motorcycle—an exceptional domestic model.

The combination of iB Lady Taiko Ooi and the H2 motorcycle stood out in the otherwise rigid machine tool exhibition, drawing great attention and enthusiastic responses from attendees.

The process of creating the cylinder involved several key steps:

• iB provided the 3D model originally designed for machining.
• The cylinder was 3D printed using advanced metal printing technology.
• iB then performed surface finishing on the top and bottom faces, as well as the intake and exhaust ports.
• Finally, the ICBM® (Aluminum Plated Sleeve) process was applied to the inner bore, completing the cylinder.

Metal 3D printing technology is drawing significant global attention, with large exhibition spaces at JIMTOF dedicated to showcasing various 3D printers.

The combination of 3D printing and iB’s expertise in internal combustion engine machining is proving to be a perfect match. Compared to iB’s traditional precision machining techniques, 3D printing allows for much faster production as long as the data is available. However, 3D printing alone does not produce a ready-to-use engine part. For example, the cylinder required bore plating and diamond honing after printing.
Even if we take on projects for other engine components like cylinder heads or crankshafts, precision finishing will always be crucial—and that’s where iB’s 70+ years of internal combustion engineering expertise becomes invaluable.

Track Testing at Tsukuba Circuit

In December, we conducted real-world testing at Tsukuba Circuit.
The cylinder was installed in a race bike ridden by Takeshi Goto, former editor-in-chief of 2-Stroke Magazine, for TOT and LOC races.

Many people wonder, “Is a 3D-printed cylinder strong enough?”
No need to worry—
It’s stronger and has better heat dissipation than aluminum castings.
And thanks to ICBM® aluminum-plated sleeves, the bore is flawless.

The testing consisted of three 20-minute full-throttle sessions, and the cylinder held up perfectly. After removing it from the bike and inspecting the bore, we found zero deformation or wear.

Why Does iB Take on These Challenges?

I often talk about my Bultaco Sherpa T when explaining iB’s mission.
Bultaco, a Spanish motorcycle brand, went out of business nearly 30 years ago. Naturally, they no longer supply parts.

Yet, when I email specialized Bultaco parts shops in the US or UK, I can get anything I need within a week—from pistons and gaskets to frame components, even T-shirts and caps!
These dedicated shops not only restore old bikes but also remanufacture critical parts and supply them worldwide.

In Japan, people tend to blame manufacturers when parts become unavailable. But the depth of motorcycle culture in the West is different.
It makes me think: Why can’t we do the same in Japan?

After all, manufacturers originally built these motorcycles from nothing—so why not make the parts ourselves?

I know some people will say, “It’s not that simple…”
Of course, it’s challenging. We don’t have the same financial resources as big corporations.
But if we give up now, the motorcycles we love—our 20th-century mechanical treasures—will disappear by the 22nd century.
We have to act now, before it’s too late.

In other words, if something doesn’t exist, we should create it to keep these legendary machines alive.

At iB, our mission is to preserve legendary motorcycles like the Kawasaki Mach 750 (H2) for future generations.
That is the very reason our company, iB Inoue Boring, exists.

Now, there are no longer any technical barriers to producing engine components with metal 3D printing.

Please remember this—
And if you ever need a rare part, don’t hesitate to reach out to iB Inoue Boring.