1951 BMW R 25/2 Specifications

Name: 1951 BMW R 25/2
Brand: BMW

All-Round • Specs last verified 13 July 2026

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1951 BMW R 25/2 Overview

The 1951 BMW R 25/2 is an all-round motorcycle built around 247 cc of displacement. Under the tank sits a Four stroke, single cylinder, pushrod operated, OHV, 2 valves per cylinder engine, a compression ratio of 6.5:1. 1951 BMW R 25/2 delivers 8.9 kW @ 5600 rpm of peak power. From a practical standpoint, the 1951 R 25/2 tips the scales at 142 Kg and carries a 12 L fuel tank. That's roughly 65.5 kg lighter than the average all-round motorcycle in our database. Scroll down for the complete 1951 BMW R 25/2 spec sheet covering every technical detail from suspension travel to tyre sizes.

1951 R 25/2 - Pros & Cons

Strengths

Capable power output: At 8.9 kW @ 5600 rpm, the R 25/2 holds its own against class rivals.
Low-maintenance final drive: Shaft final drive means no chain to clean, lube or adjust - meaningfully less routine maintenance than a chain-driven equivalent.

Considerations

Modest fuel capacity: The 12 L tank means more frequent fuel stops on longer rides, which is worth planning around on touring routes.

Wear Points & Servicing Notes

Heat management in traffic

R 25/2's air-cooled design means engine-bay temperatures build up more in stop-start traffic than on a liquid-cooled equivalent - a function of the cooling method itself, not a defect. Mesh riding gear and avoiding prolonged idling help in hot climates.

Suspension condition on used examples

Up front, the R 25/2 runs Telescopic fork and Pushrod suspension, spring loaded saddle at the rear. On a used example, check fork seals for weeping oil and test the rear linkage for play - seals are a relatively cheap fix but useful when negotiating price.

Final drive maintenance

Final drive is by shaft - no chain or belt maintenance at all, though the drive-shaft oil should be changed on the manufacturer's interval.

Frame & chassis check

The frame is Closed steel twin loop frame, welded - worth a visual check for corrosion or impact damage around the head-stock and swingarm pivot on any used example, since frame damage is far costlier to fix than any service item.

R 25/2 - Buying & Maintenance Guide

What to check before buying

When inspecting a used 1951 BMW R 25/2, start with the basics: check the service book for oil change frequency, inspect the chain and sprockets for wear, and look for oil seepage around the engine casings and rocker covers. A cold start test is invaluable - a well-maintained R 25/2 should fire up cleanly and settle to a smooth idle within a few seconds.

Oil and filter changes

Regular oil changes are the single most important maintenance task on any R 25/2. Stick to the manufacturer's interval - typically every 6,000 km or once a year, whichever comes first. Always use the correct viscosity grade as specified in the owner's manual.

Carburetor upkeep

Keep the carburetors clean and free of deposits. If the R 25/2 has been stored, strip and clean the carb float bowls before attempting to start it. Pilot jets are the first to block and the last to be checked - always include them in any carb rebuild.

1951 BMW R 25/2 - Frequently Asked Questions

What engine does the 1951 BMW R 25/2 have?

The 1951 BMW R 25/2 uses a Four stroke, single cylinder, pushrod operated, OHV, 2 valves per cylinder. engine with 247 cc of displacement. It is air cooled.

How much does the 1951 BMW R 25/2 weigh?

The 1951 BMW R 25/2 weighs 142 Kg. This is the manufacturer's wet figure.

How much power does the 1951 BMW R 25/2 make?

The 1951 BMW R 25/2 produces 8.9 kW @ 5600 rpm of power.

What is the fuel tank capacity of the 1951 BMW R 25/2?

The 1951 BMW R 25/2 has a 12 L fuel tank. At around 5-6 litres per 100 km, that is roughly 200-240 km between stops.

What brakes does the 1951 BMW R 25/2 have?

The 1951 BMW R 25/2 uses ∅160mm Drum at the front and ∅160mm Drum at the rear.

What tyre sizes does the 1951 BMW R 25/2 use?

The 1951 BMW R 25/2 runs 3 x 19" front and 3.25 x 19" rear tyres. A good selection of sport, touring and all-weather rubber is available in these sizes.

What gearbox does the 1951 BMW R 25/2 have?

The 1951 BMW R 25/2 is fitted with a 4 Speed transmission.

Key Specifications

Engine

Four stroke, single cylinder, pushrod operated, OHV, 2 valves per cylinder.

Power

8.9 kW / 12 hp @ 5600 rpm

Torque

Not published by manufacturer

Top Speed

Not published by manufacturer

Weight

142 Kg / 312 lbs

Fuel Capacity

12 L / 3.1 US gal

Full 1951 BMW R 25/2 Specifications

Year 1951 - 53

Make Model BMW R 25/2

Fuel Capacity 12 L / 3.1 US gal

Wet Weight 142 Kg / 312 lbs

Max Power 8.9 kW / 12 hp @ 5600 rpm

Displacement 247 cc / 15.1 cu in.

Engine Detail Four stroke, single cylinder, pushrod operated, OHV, 2 valves per cylinder.

Bore x Stroke 68 x 68 mm

Compression Ratio 6.5:1

Cooling System Air cooled

Fuel Induction 1x Bing type 1/22/44 or SAWE type K22F

Ignition Battery ignition

Starter Kick

Clutch Single plate, dry

Final Drive Shaft

Gear Ratios 1st 6.10 / 2nd 3.00 / 3rd 2.04 / 4th 1.54:1

Transmission / Drive 4 Speed

Frame Type Closed steel twin loop frame, welded

Suspension - Front Telescopic fork

Suspension - Rear Pushrod suspension, spring loaded saddle

Brakes - Front ∅160mm Drum

Brakes - Rear ∅160mm Drum

Tyres - Front 3.00 x 19"

Tyres - Rear 3.25 x 19"

Specifications are compiled from manufacturer documentation and cross-referenced technical sources, and corrected on an ongoing basis. Spot an error? Let us know.

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