| Feature | Specification |
|---|---|
| Model Designation | SC78A (Euro 4) |
| Production Years | 2017 – 2021 |
| Engine Type | Air/Oil-cooled Inline-4, DOHC |
| Engine Oil | SAE 10W-30 (JASO T 903 MA) (3.9 L) |
| Tire Dimensions | F: 110/80R18 / R: 140/70R18 |
| Spark Plug | NGK LMAR8A-9 |
| Battery | YTZ14S |
Engineering Highlight: The Impossible Air-Cooled Inline-Four
While the industry pivoted toward liquid cooling to satisfy tightening emissions, Honda engineers achieved a rare technical feat with the SC78A. This iteration of the CB 1100 EX features the most advanced thermal management ever applied to a production air-cooled inline-four. To meet Euro 4 standards without a radiator, Honda utilized ultra-thin cooling fins (just 2mm thick) and a sophisticated oil-cooling circuit, ensuring the aesthetic purity of the 1969 CB750 remained intact while delivering modern reliability.
Technical Maintenance Specifications
For the SC78A to maintain its legendary smooth delivery, adhering to precise fluid and component specifications is non-negotiable. The 1,140cc powerplant is optimized for SAE 10W-30 (JASO T 903 MA) oil. A total capacity of 3.9 liters is required during a full service with filter change.
Ignition and Electrical
The SC78A utilizes a high-performance NGK LMAR8A-9 spark plug, which is essential for stable combustion at the leaner air-fuel ratios required by Euro 4 logic. Electrical stability is managed by the YTZ14S battery, providing the high cold-cranking amps (CCA) necessary for the high-compression starter motor.
Chassis and Contact Patch
Unlike many modern nakeds, the EX variant retains the classic 18-inch spoked wheels. Correct tire pressure is critical for the handling characteristics of this 255kg machine:
- Front (110/80R18 M/C 58V): 2.5 bar (36 psi)
- Rear (140/70R18 M/C 67V): 2.9 bar (42 psi)
MotoSpecsLab Verdict
The Honda CB 1100 EX (SC78A) is more than a retro exercise; it is a masterclass in mechanical restraint. It offers a tactile experience that liquid-cooled bikes cannot replicate, provided the owner adheres to the strict maintenance intervals of its unique air-cooled architecture. It remains a blue-chip investment for collectors and purists alike.