1 5

INOUE BORING

YAMAHA　RZ250 Early model φ54.0 mm STD　Port with bridge　ICBM™ Aluminum Sleeve Finish Cylinder Processing

YAMAHA　RZ250 Early model φ54.0 mm STD　Port with bridge　ICBM™ Aluminum Sleeve Finish Cylinder Processing

$1,500.00
$1,500.00
Sale Sold out
Shipping calculated at checkout.

About This Service

This is a cylinder rebuild service for YAMAHA RZ250 (φ54mm) early model.
Upon receipt of your cylinder, we will rebuild it and return it to you.
Please send us only the cylinder and the corresponding piston, with payment in advance.

We will install an aluminum sleeve plated with nickel-silicon-carbide (hardness second only to diamond) and ensure proper piston clearance before returning it to you.

This rebuild also features Inoue Boring’s original “Bridge-Port” specification, a unique pillar-type port structure designed to enhance durability and gas flow stability — ideal for high-performance and long-lasting results.

Never Wears Out. Seizure-Proof. Lightweight.

  • Ride right away—no break-in required

  • Exceptionally long-lasting

  • One-third the weight of cast iron

  • 5× the heat transfer of cast iron

  • Rust-free

What is ICBM™ Processing?

  1. Remove the original cast-iron sleeve.

  2. Install a precision nickel-silicon-carbide-plated aluminum sleeve.

  3. Ride with a lightweight, ultra-durable cylinder that preserves itself as you go.

How to Order

  1. Click [Add to Cart] to purchase the machining service only.

  2. Complete the quote/service form below.

  3. Within one business day we’ll confirm schedule by email.

  4. Print the confirmation PDF and include it when you ship us your parts.

  5. After machining, we inspect every component and ship it back to you.

Shipping address: 

Inoue Boring Co., Ltd.
〒350-1155 Saitama Prefecture Kawagoe City Shimoakasaka Onohara 671
℡：+81-49-261-5833

We Buy Your Spare Cylinders

Upgraded to ICBM™ cylinders? Sell your leftover originals to us—just submit a buy-back request through our inquiry form.


**Need pistons supplied? Request a quote on our Estimate Request page.
Processing takes about 20 business days.

All work is completed in our insured, domestic facility, and every component is quality-guaranteed. Ride with confidence—preserve your engine for the next generation.

 

Inquiry

Inquiry about the product

Shipping

Shipping Policy

Refund

Refund Policy

View full details

ICBM™ gives your engine alive again!

  1. Long-lasting super durability
  2. Preserve your engine while riding
  3. Feel the engine's pulse forever!

“We want to create a cylinder that doesn't wear down...” This has been Inoue Boring’s long-held dream. This technology dramatically improves the durability of the cylinder bore by manufacturing an aluminum sleeve and applying a special plating to the inside diameter.

LEARN MORE

Why ICBM™ is "Revolutionary”

✔ Exceptional wear resistance
✔ Lightweight
✔ Low friction (reduces ring wear)
✔ Highly resistant to seizure
✔ Excellent heat dissipation
✔ Uniform expansion rate
✔ And it’s rust-resistant!

TESTIMONIALS

”Elegance Reborn: My Mach III Runs Like New”

My Kawasaki Mach III is over 50 years old. Many parts were worn out, so I used Inoue Boring’s modern engine work to bring it back. With  ICBM™ treatments, it runs smooth and strong. It won First Place at a restoration contest hosted by Inoue Boring. This bike is old—but alive.

-Mr.Hirakawa　Kawasaki H1 Owner　
Japan

”Back to Life: My Orange H1-B with ICBM™”

“After years in storage, I brought my H1-B back with Inoue Boring’s ICBM™ treatment. The old cast-iron sleeve was replaced with an aluminum one, letting me return to the standard bore. I even added a bridge port. It’s not about more power—it’s about bringing back the ride I remember.”

-Mr. Katsumi Taguchi　Kawasaki H1-B Owner
Japan

READ MORE

BLOG

View all
1 3
View all