Simson SCHWALBE KR51 (1964–1980) — Specs
Identity
Manufacturer: Simson
Model: SCHWALBE KR51
Category: Motorcycle
Type: Motorcycle
Years: 1964 → 1980
Engine
Displacement (cc): 50
Cylinders: 1
Power (hp): 3
Power (kW): 2
Torque (Nm): 4
Dimensions
Overall length: 1830 mm
Overall width: 700 mm
Overall height: 1090 mm
Wheelbase: 1290 mm
Ground clearance: 115 mm
Weight (kg): 80
Seat height (mm): 760
Tank (L): 6.8
Tires
Front pressure (bar): 1.25
Rear pressure (bar): 1.5
Drivetrain
Drive chain: 114 links
Sprockets (front / rear): 13 / 14
Ignition
Spark plug: NGK B9HS
Plug gap: 0.5 mm
Fuel consumption
Estimated fuel consumption: ~2.5 L/100 km
Estimated range: ~272 km on a full tank (6.8 L)
Note: estimate based on engine size + bike type. Real-world ±20%.
Service
Service interval (km): 3000
Service interval (months): 12
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 3,000 km or 12 months, whichever comes first. Spark plug: NGK B9HS (gap 0.5 mm). Chain: 114 links, sprockets 13/14 teeth. Tire pressure: front 1.25 bar, rear 1.5 bar (cold). 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: 2-stroke autolube (JASO FC), separate mix-oil reservoir
- OEM OEM 2-stroke oil (JASO FC/FD)
- Premium Motul 710 2T (100% Synthetic)
- Premium Motul 510 2T Technosynthese (Semi-Synthetic)
- Standard Repsol Moto Sintetico 2T (Synthetic)
- Standard Elf Moto 2 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
Spec: Not applicable — 2-stroke engine has no replaceable oil filter cartridge
- OEM 2-stroke engine — no engine-oil filter to replace.
- OEM Use the recommended 2-stroke oil grade listed above — clean oil is your only filtration.
Spark plug
Spec: NGK B9HS, gap 0.5 mm
- OEM NGK B9HS
- Premium NGK B9HSIX
Front brake pads
Rear brake pads
Front tire
Spec: 1.25 bar
Rear tire
Spec: 1.5 bar
Brake fluid
Coolant
Service interval
Spec: 3 000 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: Not applicable — 2-stroke engine has no valves
- OEM 2-stroke engine — no valve clearance to inspect.
- OEM Inspect piston, rings and cylinder at engine rebuild intervals (~30–50 hours for race, longer for street).
- OEM Check exhaust power-valve operation (if equipped) every 20–30 service hours.
Air filter
Drive chain
Battery
- Premium Yuasa YTX5L-BS or YT4B-BS (typical 50-125cc)
