BMW R 66 (1938–1941) — Specs
Identity
Manufacturer: BMW
Model: R 66
Category: Motorcycle
Type: Motorcycle
Years: 1938 → 1941
Engine
Displacement (cc): 597
Cylinders: 2
Power (hp): 30
Power (kW): 22
Torque (Nm): 39
Dimensions
Overall length: 2150 mm
Overall width: 810 mm
Overall height: 1180 mm
Wheelbase: 1450 mm
Ground clearance: 155 mm
Weight (kg): 187
Seat height (mm): 700
Tank (L): 14
Tires
Front tire: 3.25-18
Rear tire: 3.50-18
Front pressure (bar): 1.4
Rear pressure (bar): 1.9
Drivetrain
Final drive: Shaft drive
Ignition
Spark plug: NGK B7HS
Plug gap: 0.5-0.6 mm
Fluids & Filters
Engine oil (with filter, L): 1.65
Oil filter: OEM oil filter
Air filter: OEM air filter
Brake fluid: DOT 4
Fuel consumption
Estimated range: ~291 km on a full tank (14.0 L)
Service
Battery: OEM battery specification
Service interval (km): 10000
Service interval (months): 12
Valve check (km): 24000
Parts and consumables for this motorcycle
Data is gathered with care, but without guarantee. Always confirm critical information with your dealer or workshop.
Service notes
Service interval: every 10,000 km or 12 months, whichever comes first. Valve clearance check every 24,000 km. Valve clearance — intake cold 0.10-0.15 mm, exhaust cold 0.10-0.15 mm. Engine oil: 1.65 L with filter change. Spark plug: NGK B7HS (gap 0.5-0.6 mm). Drive: shaft drive. Tire pressure: front 1.4 bar, rear 1.9 bar (cold). Tire size: front 3.25-18, rear 3.50-18. Always confirm critical values with the workshop manual or an authorised dealer.
OEM and quality aftermarket parts that fit this bike. Always confirm with your dealer before ordering.
Engine oil
Spec: nan, 1.65 L (with filter)
- OEM OEM recommended engine oil
- Premium Motul 7100 4T (100% Synthetic, Ester)
- Premium Motul 5100 4T Technosynthese (Semi-Synthetic)
Which Motul for this bike?
| Motul 7100 4T ✓ | Motul 5100 4T | |
|---|---|---|
| Product | Motul 7100 4T — 100% fully synthetic | Motul 5100 4T — semi-synthetic |
| Best for | Sport, Naked, Adventure (600cc+), track | Standard, Cruiser, Scooter, daily use |
| RPM protection | Excellent — ester base, stable under load | Good — for normal riding conditions |
- Standard Repsol Moto Racing 4T (Synthetic)
- Standard Elf Moto 4 Tech (Semi-Synthetic)
Fully Synthetic vs Semi-Synthetic
| Fully Synthetic | Semi-Synthetic | |
|---|---|---|
| Base oil | 100% chemical synthesis (ester or PAO) | Mineral oil + synthetic additives |
| Heat resistance | Excellent — stable at extreme heat & RPM | Good — suitable for normal temperatures |
| Cold start | Better — reaches engine faster when cold | Good — adequate for normal climates |
| Change interval | Longer (up to 10,000 km) | Shorter (5,000–7,000 km typical) |
| Price | Higher | Lower |
Oil filter
Air filter
Spark plug
Spec: NGK B7HS, gap 0.5-0.6 mm
- OEM NGK B7HS
- Premium NGK B7HSIX
- Standard NGK B7HS
Front brake pads
Spec: EBC FA095HH
- Premium EBC FA095HH
Rear brake pads
Spec: EBC FA095HH
- Premium EBC FA095HH
Front tire
Spec: 3.25-18, 1.4 bar
- OEM OEM 3.25-18
Rear tire
Spec: 3.50-18, 1.9 bar
- OEM OEM 3.50-18
Battery
- Premium Yuasa YTX12-BS or YTZ10S (typical 500-750cc)
Brake fluid
- Standard TotalEnergies HBF4
Coolant
Service interval
Spec: 10 000 km / 12 months
- OEM Engine oil + oil filter change
- OEM Air filter inspection
- OEM Spark plug check
- OEM Brake fluid replacement: every 2 years
Valve check
Spec: 24 000 km
- OEM Intake clearance: cold 0.10-0.15 mm
- OEM Exhaust clearance: cold 0.10-0.15 mm
Suspension
Spec: telescopic fork ÖLGEDÄM.
- OEM Fork: telescopic fork ÖLGEDÄM.
Drive chain
