| Model Type | 0358 / 0359 / 248 |
|---|---|
| Production Years | 1978 – 1985 |
| Engine Oil | SAE 20W-50 Mineral (2.0 L) |
| Tire Dimensions | F: 90/90-18 51H | R: 110/90-18 61H |
| Tire Pressure | F: 2.0 bar (29 psi) | R: 2.2 bar (32 psi) |
| Battery Type | DIN 52015 |
| Spark Plug | Bosch W7DC |
While the larger BMW R-series boxers were known for their low-end torque and touring prowess, the BMW R 65 (Type 248) carved a unique niche in motorcycling history. Unlike its siblings, the R 65 featured a distinctively short-stroke engine architecture (82mm bore x 61.5mm stroke). This engineering choice allowed the R 65 to rev significantly higher and more freely than the R 80 or R 100, providing a sporting character that was unprecedented for the mid-sized air-head boxer lineup.
Technical Engineering Deep-Dive
The R 65 and its more aggressive sibling, the LS (designed by Hans Muth), utilized a narrower frame and shorter swingarm compared to the heavy-duty /7 series. This resulted in a more compact, flickable machine that excelled in European urban environments and twisty B-roads. The engine delivered approximately 45-50 hp, which, combined with the reduced weight, offered a power-to-weight ratio that challenged many of its 750cc contemporaries.
Maintenance Guide & Essentials
Proper lubrication is the lifeblood of the Type 248 engine. At MotoSpecsLab, we emphasize the use of high-quality SAE 20W-50 Mineral oil. Synthetic oils of the era can often lead to seal weeping in these vintage blocks. A total capacity of 2.0 liters is required for a standard change including the filter.
Ignition and Electrical
The electrical system relies on the DIN 52015 standard battery. For optimal combustion and cold-start reliability, the Bosch W7DC spark plug remains the gold standard for this specific compression ratio. Gap settings should be checked periodically to maintain the crisp throttle response the short-stroke engine is known for.
Chassis and Tires
The 18-inch wheels front and rear contribute to the bike’s balanced handling. We recommend a 90/90-18 on the front and a 110/90-18 on the rear. Maintaining the factory-specified pressures of 2.0 bar (Front) and 2.2 bar (Rear) is critical; under-inflation leads to heavy steering and accelerates the ‘cupping’ of the front tread—a common issue on these lighter boxers.
The LS Variant: A Design Icon
The R 65 LS (1981-1985) remains one of the most visually striking BMWs ever produced. With its wedge-shaped bikini fairing and distinctive alloy wheels, it represented BMW’s first serious foray into modern ‘sport’ styling. Mechanically identical to the standard R 65 in most respects, the LS featured dual front disc brakes as standard, significantly improving stopping power over the early single-disc R 65 models.
Frequently Asked Questions (FAQ)
Can I use synthetic oil in my R 65?
While modern synthetics offer great protection, the gaskets and tolerances of the 1978-1985 Boxer engines are best suited for 20W-50 Mineral oil to prevent leaks and ensure proper internal pressure.
What is the benefit of the short-stroke design?
The shorter stroke reduces piston speed at high RPMs, allowing the engine to rev higher safely, which provides a more linear and ‘sporty’ power delivery compared to the ‘thumping’ nature of long-stroke boxers.