Honda GB350 / GB350C / CB350 (NC59) — OEM Fluid, Tire Pressure & Maintenance Specs
348cc Air-Cooled Ultra-Long-Stroke Single SOHC 2-Valve Dual-Balancer (Wet Assist/Slipper) · Source: Honda GB350 / GB350C / CB350 (NC59 / NC64) Official Owner’s Manual Maintenance Specifications
According to the Honda GB350 / GB350C / CB350 (NC59 / NC64) Official Owner’s Manual Maintenance Specifications, the 2021–Present Honda GB350 / GB350C / CB350 (NC59) (chassis NC59/NC64) requires 2 L (2.11 US qt) of SAE 10W-30 (JASO MA, API SJ or higher) engine oil for a drain-only change and 2.05 L (2.17 US qt) with filter service (15412-K0N-D01 / HF569). Standard solo cold tire pressure is 200 kPa / 2.00 bar / 29 PSI front (100/90-19 M/C 57H) and 225 kPa / 2.25 bar / 33 PSI rear (130/70-18 M/C 63H), paired with 1× NGK MR6K-9 spark plug(s) and a YTZ8V battery.
Drain only: 2 L (2.11 US qt)
R 225 kPa (2.25 bar)
Est. Range: ~615 km (382 mi)
1. Engine Lubrication, Filter & Clutch Specifications
| Clutch Architecture | Wet Multi-Plate Manual Clutch NEVER use JASO MB |
|---|---|
| Recommended Viscosity & Grade | SAE 10W-30 (Alt: SAE 10W-40) · JASO MA · API SJ or higher |
| Oil Volume (Drain / With Filter / Overhaul) |
• Drain only: 2 L (2.11 US qt) • With filter/strainer: 2.05 L (2.17 US qt) • Complete dry overhaul: 2.5 L (2.64 US qt) |
| OEM Oil Filter Code & Type | 15412-K0N-D01 / HF569 |
| Correct Oil Level Check Method | Hold upright on level ground; rest dipstick UNTHREADED on filler neck (do NOT screw in) |
| Oil Drain Bolt Torque | 24 N·m (17.7 lb-ft / 2.45 kgf·m) — Use fresh crush washer |
2. Cold Tire Pressures, Wheels, Ignition & Drivetrain
| Front / Rear OEM Tire Sizes | Front: 100/90-19 M/C 57H · Rear: 130/70-18 M/C 63H (Tubeless) |
|---|---|
| Cold Tire Pressure — Solo Riding |
Front: 200 kPa / 2.00 bar / 29 PSI Rear: 225 kPa / 2.25 bar / 33 PSI |
| Cold Tire Pressure — 2-Up / Loaded Touring |
Front: 200 kPa / 2.00 bar / 29 PSI Rear: 250 kPa / 2.50 bar / 36 PSI |
| OEM Spark Plug & Quantity | NGK MR6K-9 × 1 (Gap: 0.8–0.9 mm) |
| OEM Battery Code & Rating | YTZ8V (12V 7.0Ah MF AGM) |
| Final Drive Maintenance | 520 Sealed O-Ring Chain (104 links) — Maintain 25–35 mm slack |
| Brake Fluid & Coolant | DOT 4 · Air-Cooled Vertical Single (No liquid coolant — internal piston oil-jet cooling) |
3. Ergonomics, Range & Scheduled Service Intervals
| Displacement · Max Power · Peak Torque | 348 cc · 20.3 hp @ 5,500 rpm · 29 N·m (21.4 lb-ft) @ 3,000 rpm |
|---|---|
| Seat Height & Wet Curb Weight | 800 mm (31.5 in) · 179 kg (395 lbs) |
| Fuel Tank & Est. Real-World Range | 15 L (4.0 US gal) · ~41 km/L → ~615 km (382 mi) |
| OEM Scheduled Maintenance Intervals |
• First Break-In: 1,000 km • Engine Oil / Filter: 6,000 km / 12,000 km • Air Filter / Spark Plug: 18,000 km / 12,000 km • Valve Clearance Check: 12,000 km |
4. Generation Cutoffs & Real-World Wrenching Gotchas
Model-Year & Chassis Generation Notes
Sold as GB350, vintage-fendered GB350C (NC64), and H’ness CB350, all variants share the exact 70.0 × 90.5 mm 348cc single, 2.0–2.05 L oil capacity, and 15412-K0N-D01 filter—except the GB350S, which swaps the 130/70-18 rear wheel for a 150/70R17 radial.
Oil & Clutch Mechanical Engineering Note
Unlike Royal Enfield’s 350 (which specifies 15W-50), Honda’s walled crankcase architecture and piston cooling jet run strictly on low-drag SAE 10W-30 JASO MA oil (~2.0 L drain / ~2.05 L with 15412-K0N-D01 paper filter element).
Garage Wrenching Gotchas
- Despite its classic silhouette, the 19-inch front and 18-inch rear cast-alloy wheels wear tubeless tires—meaning roadside punctures can be plugged in minutes without pulling tubes.
- Because 5th gear is a tall highway overdrive, avoid lugging the long-stroke single below 50–55 km/h in top gear; downshift cleanly using the light assist-and-slipper clutch.
5. Frequently Asked Questions (FAQ)
What is the oil capacity and filter code for the Honda GB350 / CB350?
Fill ~2.0 L drain-only or ~2.05 L when replacing the 15412-K0N-D01 (HF569) paper oil filter element (2.5 L dry overhaul) with SAE 10W-30 JASO MA oil, checked upright via the unthreaded dipstick.
What cold tire pressure is recommended for the Honda GB350?
Cold inflation pressure is 200 kPa (29 PSI) front and 225 kPa (33 PSI) rear solo, or 250 kPa (36 PSI) rear when riding two-up.
What is the real-world fuel range of the Honda GB350?
Combining a 15.0 L fuel tank with ~41 km/L real-world consumption, the GB350 easily clears 550+ km (340+ miles) between fill-ups.