| Specification | Data |
|---|---|
| Model Series | Honda CB 750 K (KZ/KA/KB) – RC01 |
| Production Years | 1978 – 1982 |
| Engine Oil | SAE 10W-40 (API SE, SF, SG) |
| Oil Capacity | 3.2L (Drain) / 3.5L (Filter) / 4.0L (Dry) |
| Tire Size (F/R) | F: 100/90-19 54H / R: 120/90-18 64H |
| Tire Pressure | F: 2.0 bar / R: 2.25 bar (2.8 bar with pillion) |
| Battery | YB14L-A2 |
| Spark Plug | NGK DR8ES-L (Gap: 0.6 – 0.7 mm) |
The Honda CB 750 K (RC01) represents a pivotal moment in motorcycling history: it was the platform that retired the legendary SOHC (Single Over-Head Cam) engine in favor of the sophisticated 16-valve DOHC (Double Over-Head Cam) architecture. This engineering shift allowed Honda to regain its dominance in the Superbike class, providing a broader powerband and increased thermal efficiency that the aging SOHC design could no longer sustain against its rivals.
Engineering Deep-Dive: The 16-Valve Powerplant
The RC01, encompassing the KZ, KA, and KB variants, features an air-cooled, inline-four engine. Unlike its predecessor, the use of four valves per cylinder significantly improved gas flow, allowing the engine to breathe better at high RPMs. The bucket-and-shim valve adjustment system, while more complex to service than the old screw-and-locknut type, provided greater valve train stability at the 9,500 RPM redline.
Maintenance Guide & Essentials
Lubrication System
For the RC01, maintaining oil quality is paramount due to the high-revving nature of the DOHC head. We recommend a high-quality SAE 10W-40 meeting API SE, SF, or SG standards. Note the capacities: a standard oil change requires 3.2 liters, while including a filter change bumps this to 3.5 liters. If the engine has been fully disassembled, the dry capacity is 4.0 liters.
Ignition & Electrical
The RC01 utilizes an electronic ignition system, a significant upgrade for reliability. However, the spark plugs remain a critical maintenance item. The NGK DR8ES-L is the standard fitment. Precision is key here; ensure the electrode gap is set strictly between 0.6 and 0.7 mm to prevent misfires or coil stress. The electrical system is supported by a YB14L-A2 lead-acid battery.
Chassis & Tires
The CB 750 K maintains a classic 19-inch front and 18-inch rear wheel setup. For modern road use, the 100/90-19 54H (Front) and 120/90-18 64H (Rear) provide the best balance of period-correct aesthetics and contemporary grip. Pressure should be maintained at 2.0 bar (28 psi) in the front and 2.25 bar (32 psi) in the rear for solo riding, increasing the rear to 2.8 bar (40 psi) when carrying a passenger.
MotoSpecsLab Verdict
The RC01 is a robust machine, but it demands disciplined maintenance. Its 16-valve head is sensitive to oil starvation and neglected valve clearances. When properly tuned, the CB 750 K offers a smooth, linear power delivery that remains competitive even by modern standards. It is the quintessential ‘Universal Japanese Motorcycle’ (UJM) refined for the high-performance era.