HONDA 12100-056-670 Cylinder Ar

( Manufacturer Part Number: 12100-056-670 ), ( Part Type: Cylinder ), ( Vintage Part: Yes )

Review HONDA To Cylinder Ar yellow fits CT90 1970–1972

The **Honda 12100-056-670 CT90 cylinder (AR-Yellow)** is a meticulously crafted, high-performance replacement cylinder kit designed exclusively for Honda s legendary **CT90** two-stroke motorcycles produced in **1970 and 1972**. This precision-engineered component is a direct replacement for the original factory cylinder, ensuring seamless integration with the bike s stock engine while delivering enhanced reliability, durability, and performance. Crafted from **high-grade cast iron**, the cylinder is machined to Honda s exacting specifications, featuring a **smooth, honed bore** that optimizes piston sealing and reduces friction for improved efficiency. The **AR-Yellow finish** not only provides a striking, vintage-inspired aesthetic but also offers a slight thermal resistance benefit, helping to dissipate heat more effectively during high-speed or extended riding sessions. This cylinder is paired with a **compatible piston, rings, and gasket set** (often included in the same kit), ensuring a complete, ready-to-install solution for riders seeking to restore or upgrade their CT90 s engine. Whether restoring a classic bike to its original glory or fine-tuning an existing setup, this cylinder kit embodies Honda s commitment to engineering excellence, blending historical authenticity with modern performance standards. Its robust construction and attention to detail make it an ideal choice for enthusiasts who demand both heritage charm and dependable power.

### **Pros and Cons of Buying a 1970 1972 Honda CT90 (Cylinder: AR-Yellow, Part Number: 12100-056-670)**

#### **Pros**

1. **Classic Design and Nostalgia** The CT90 is a rare and iconic early Honda motorcycle, appealing to collectors and enthusiasts who appreciate vintage Japanese engineering. Its simple, utilitarian design reflects the practical yet stylish aesthetic of the 1970s.

2. **Reliability of Early Honda Engines** Honda s early air-cooled single-cylinder engines (like the CT90 s 90cc unit) were known for durability and simplicity. With proper maintenance, these bikes can last decades with minimal issues beyond basic wear.

3. **Low Cost of Ownership (If Well-Maintained)** Parts for a CT90 are relatively inexpensive compared to modern bikes, especially if you source them from Honda s legacy parts catalog or aftermarket suppliers. Labor costs for basic repairs are also low.

4. **Lightweight and Maneuverable** At just under 200 lbs (90 kg), the CT90 is easy to handle, making it ideal for urban commuting, parking in tight spaces, or casual riding. Its small size also contributes to fuel efficiency.

5. **Fuel Efficiency** The 90cc engine delivers impressive mileage, often exceeding 100 mpg (43 km/l) in real-world use, making it cost-effective for short trips.

6. **Minimalist Maintenance Requirements** Unlike modern bikes with complex electronics, the CT90 has few moving parts beyond the engine, transmission, and basic drivetrain. Oil changes, chain adjustments, and tire rotations are the primary upkeep needs.

7. **Potential for Restoration or Customization** If you enjoy working on bikes, the CT90 offers a fun project. Restoring one to original condition or modifying it (e.g., upgrading the exhaust, adding a modern seat, or installing a digital speedometer) can be rewarding.

8. **Low Insurance Costs** As a vintage bike, insurance is typically cheaper than for modern sport or touring motorcycles, especially if it s registered as a classic.

9. **Community and Enthusiast Support** There are active forums (e.g., Honda CT90 groups on Facebook, vintage motorcycle clubs) where owners share tips, modifications, and restoration advice. This can be invaluable for troubleshooting or finding parts.

10. **Environmentally Friendly** The CT90 s small engine produces minimal emissions, making it a low-impact choice for casual riding.

---

#### **Cons**

1. **Age and Wear** A 1970 1972 CT90 will almost certainly show signs of age, including rust (especially in the frame, swingarm, or exhaust), worn tires, and degraded seals. The bike may require significant restoration work to be road-legal and reliable.

2. **Limited Power and Performance** The 90cc engine produces only about 5 6 horsepower, making it slow by modern standards. Acceleration is sluggish, and top speed is around 40 50 mph (65 80 km/h), which may be frustrating for riders expecting more power.

3. **Poor Weather Protection** The CT90 lacks a full fairing or windscreen, leaving the rider exposed to wind, rain, and debris. This can make long rides uncomfortable, especially in adverse conditions.

4. **Basic Comfort** The seat is hard and narrow, and there s no suspension (or very minimal) in the early models, leading to a bumpy ride on rough roads. Modern ergonomics (e.g., adjustable handlebars, footpegs) are absent.

- **Rust in the frame or swingarm** (common in older Hondas exposed to moisture).

- **Worn or stretched chain** (leading to poor shifting and potential derailment).

- **Leaking oil seals** (causing oil loss and potential engine damage).

- **Faulty carburetion** (early CT90s use a simple but finicky carburetor that may need cleaning or adjustment).

- **Brake wear** (drum brakes on early models can be weak; upgrading to disc brakes is a common mod).

6. **Limited Aftermarket Support** While parts exist, they may be harder to find than for more common bikes (e.g., CB750, GS500). Some components (e.g., original Honda parts) may require sourcing from specialty vendors or eBay.

7. **No Modern Safety Features** There s no ABS, traction control, or advanced lighting. The bike relies on basic mechanical braking and visibility, which can be risky in traffic.

8. **Resale Value is Low** Even in good condition, a restored CT90 won t hold significant value. It s primarily a hobby bike for enthusiasts, not an investment.

9. **Legal Restrictions** Some jurisdictions have helmet laws or require modern safety equipment (e.g., turn signals, reflectors). The CT90 may need modifications to comply with current regulations.

10. **Not Suitable for Long Distances** The lack of comfort, power, and weather protection makes it impractical for touring or long rides. It s best suited for short, casual urban or countryside trips.

---

### **Conclusion**

Buying a 1970 1972 Honda CT90 (especially one with the AR-Yellow cylinder and the specified part number) is a decision that hinges on your priorities. If you value **nostalgia, simplicity, and the challenge of working on a vintage bike**, the CT90 can be a rewarding project. Its low cost, fuel efficiency, and reliability (if well-maintained) make it an attractive option for riders who enjoy the basics of motorcycle ownership.

However, if you prioritize **comfort, power, modern safety, or practicality for daily use**, the CT90 s limitations will likely outweigh its charms. It s not a bike for serious commuting, highway riding, or long-distance travel it s a **collector s item or a hobbyist s plaything**.

The **12100-056-670 cylinder** (a rare or restored part) suggests the bike may have been in better hands than average, but you should still inspect it thoroughly for rust, engine condition, and overall structural integrity. A **pre-purchase inspection by a motorcycle mechanic familiar with vintage Hondas** is highly recommended.

---

### **Recommendation**

- You re an enthusiast who enjoys restoring or modifying classic bikes.

- You have experience working on motorcycles and are prepared for potential repairs.

- You re okay with its limitations (slow speed, no fairing, basic comfort) and plan to use it for short, casual rides.

- You find the bike s rarity and historical significance appealing.

- You re willing to invest time (not just money) to bring it back to road-legal condition.

- You need a reliable, comfortable, or powerful bike for daily use.

- You re not comfortable with basic mechanical maintenance or don t have access to a mechanic.

- You expect modern features (e.g., disc brakes, fairing, suspension).

- You re looking for a bike that holds value or is practical for long trips.

- You dislike the idea of a slow, exposed ride.

- If you love the CT90 s simplicity but want something slightly more modern, consider a **1975 Honda CT125** (which has a slightly larger engine and better brakes).

- For a more practical vintage bike, a **Honda CB750 (1968 )** or **Yamaha XS650** offers more power and comfort while still being classic.

- If you re open to modern bikes with retro styling, a **Kawasaki W800** or **Yamaha XSR700** provides a balance of vintage aesthetics and contemporary reliability.

Ultimately, the CT90 is a **love-it-or-leave-it bike**. If you re passionate about its era and willing to embrace its quirks, it can be a fantastic addition to your collection. If not, there are plenty of other options that offer better practicality or performance.

Details:

Clean, no broken fins. I don't think is was ever bored out.Smooth cylinder walls.

part #: 12100056670 price

• $199.99

specifications cyclevintagee:

• for models: Ct90
• for makes: Honda
• for years: 1970-1972
• mpn: 12100-056-670
• part type: Cylinder
• vintage part: Yes

seller cyclevintagee:

• rating: 99.4%
• city: Jackson, Missouri
• # reviews: 609

shipping cyclevintagee:

• carrier: USPS
• type: Fixed
• cost: $12.00
• service: USPS Ground Advantage
• transit: 4-10 Days
• class: Standard

offer cyclevintagee:

• options: Ship-to-home
• quantity: 1
• sold: 0
• started: February 23, 2026
• availability: In Stock

general cyclevintagee:

• Parts Accessories > Motorcycle Scooter Parts Accessories > Other Motorcycle Scooter Parts Accessories
• condition: Used

payments cyclevintagee:

• wallet: Google-pay
• other
• credit card: Visa

returns cyclevintagee:

• policy: No Returns

Honda 12100-056-670 Is Similar To:

• 103-93-a Rensen Honda Yamaha Nos Acorn Engine Cylinder Head Nut Set (34.1% similar) Please look at all the pictures and read whole. They may not be clean. Any questions. They may have repairs. Oem original equipment manufacturer which may be new or used items for that machine. They may need some repairs. It is also cheaper if you do not need a lift gate truck. Not looking at the ...(April 25th, 2018)
• 12100-358-670 Honda Oem Cylinder Jug (52.2% similar) If the cost seems high, especially on combine shipping items, before paying. They will not look like new parts. Ecm-cycle attn: dept. No deep scratches or gouges that can be felt. Measures 71MM which is. Please look at all the pictures and read whole. All threads are good. No bent fins. What you see...(October 19th, 2017)
• 12100-ka3-740 Honda Fresh 030 Cylinder (48.9% similar) Cylinder head was also reconditioned has some small marks in chamber as shown over with matching Wisc piston wring wrist pin clips bearing and cosmetic top end gasket kit CR125 complete. Cylinder is freshly bored and honed...(January 24th, 2018)
• 12100-235-000 Honda Ca175 Cb175 Cd175 Cl175 Sl175 Cylinder Genuine Japan P N (36.4% similar) Some grease on the fins. Honda CA175 CB175 CD175 CL175 SL175 cylinder genuine japan P/N cylinders are stock bore, was honed and not run since. Top and bottom inside cylinders have nice cross hatch but middle is not consistent. It will run but I would recommend getting it bored out. There is some ...(May 24th, 2016)
• 12101-063-010 12191-044-000 13101-044-030 Honda Oem Cylinder Piston Gasket (26.2% similar) Used cylinder, piston gasket out of a honda PC50. Also fits the P50...(September 9th, 2018)
• 12107-ksr-730 Honda Cover Left Cylinder Side Nos Fits (36.7% similar) Cover, left cylinder side nos honda P/N KSR-730 fits CR125R. Note: my site only ships within the USA...(December 7th, 2018)
• 12191-ks7-700 Honda Nos Oem Cylinder Gasket Xr (37.3% similar) I haven't messed with this stuff in years so do your research as I'm not much help for if it will fit you bike...(May 22nd, 2018)
• 12200-169-000 Honda Oem Cylinder Head Elsinore Cr Ahrma (34.2% similar) If the cost seems high, especially on combine shipping items, before paying. Oem original equipment manufacturer which may be new or used items for that machine. Not asking questions, gets you the wrong part every time guaranteed. No bent fins, broken fins. Some light pitting in the combustion ...(May 3rd, 2018)
• 12200-356-010 Honda Xl Engine Cylinder Head Valves (35.8% similar) Good used cylinder head, it fits honda XL350 model's part number, will probably need the valves ground before being...(May 6th, 2018)
• 12200-357-030 Honda Cylinder Head 1973 (34% similar) Will restore very nicely. Thanks and good luck honda Elsinore CR250M cylinder head very nice condition ready to finish...(July 11th, 2017)
• 12200-381-000 Honda Cr Elsinore Cylinder Head Vintage (33% similar) Selling a rare and complete oem original cylinder head from 1975 honda Cr 250. Please review all pictures before purchasing to note actual condition of the parts and what are included. May fit other years and model's but research before you purchase. Bolt on and ride. From a good running vintage ...(June 12th, 2018)