1955–1966 BMW R26 / R27 Repair Manual (P/N 9099 136)

• Covers BMW R26 and R27 single-cylinder motorcycles as documented in the July 1962 printing, identified as BMW factory repair manual P/N 9099 136.
• Covers cylinder-head and valve repair, cylinder and piston inspection, generator and advance-unit removal, model-specific camshaft and timing-chain work, clutch and flywheel service, oil-pump access, crankshaft installation, valve adjustment, ignition timing, and carburetor setup.
• Details 4-speed transmission removal and overhaul, the foot-operated gear-change mechanism, primary and secondary shafts, kickstarter, speedometer drive, neutral contact, propeller shaft, and final-drive setup with backlash and tooth-contact checks.
• Includes wheel-bearing service, brake-lining replacement, wheel lacing and truing, suspension-unit disassembly, front swing-arm and fork repair, plus conversion and alignment work for the BMW “Standard” sidecar and its hydraulic brake.
• Provides separate R26 and R27 wiring diagrams, charging-system tests, regulator and generator service, ignition and lighting fault charts, and checks for the battery, horn, switches, neutral indicator, and sidecar lighting.
• Lists Matra and shop-made special tools with tool numbers, along with technical-data tables, fits and clearances, torque specifications, lubrication data, wear limits, and illustrations numbered through Fig. 235.

Factory Repair Scope

The repair-manual PDF contains 158 pages and reproduces a BMW workshop publication rather than an owner’s maintenance handbook. It was written for trained mechanics working in a properly equipped motorcycle shop, so familiar operations are sometimes abbreviated while model-specific measurements, tool use, cautions, and assembly exceptions receive the detail. English is included, but it is interleaved with German, French, and Spanish content rather than presented as an English-only manual.

Engine coverage runs well beyond routine tune-up work. The manual addresses cylinder-head removal, valve and spring inspection, valve-guide and valve-seat replacement, cylinder and piston measurement, connecting-rod and crankshaft work, clutch and flywheel removal, oil-sump and oil-pump service, and carburetor and air-cleaner adjustment. Separate R26 and R27 procedures cover the generator and centrifugal-advance arrangement, camshaft drive, timing-chain installation, and ignition timing, so the two engine builds are not treated as interchangeable.

Drivetrain sections explain how the rear wheel, rear drive, gearbox, engine, and complete engine-transmission block are removed and refitted before moving into internal repair. The transmission chapter covers the drive flange, gear shafts, selector mechanism, primary and secondary shafts, kickstarter, speedometer drive, and neutral-indicator contact. Final-drive work includes propeller-shaft removal, seal and bearing service, matched pinion-and-crown-wheel identification, shim selection, backlash measurement, and tooth-contact pattern inspection.

A significant R27 serial break is called out: direct gearbox removal under operation D3 applies from frame number 375893, while machines through 375892 use the engine-transmission-block procedure in D5. The chassis chapters also distinguish solo and sidecar configuration. Sidecar conversion coverage includes the final-drive ratio and speedometer change, front swing-arm and suspension repositioning, heavier rear springs, frame attachment hardware, lighting connection, toe-in and camber setup, hydraulic-brake filling and bleeding, and sidecar brake sequencing.

Electrical, Tools, and Visual References

Electrical information separates the R27 generator and Bosch Z regulator arrangement from the R26 generator with Bosch F regulator. It includes switch functions, terminal and cable identification, battery and charging maintenance, regulator-contact service limits, ignition-system fault isolation, generator no-load and load tests, cut-in and reverse-current checks, and removed-armature and field-coil testing. The dedicated R26 and R27 wiring diagrams are backed by troubleshooting tables for starting, charging, lighting, and intermittent-circuit faults.

Representative visual material includes model-specific camshaft and timing-chain indexing views, clutch and flywheel photographs, transmission-shaft and selector layouts, final-drive gear-contact patterns, wheel-spoke lacing and truing references, the two wiring diagrams, and sidecar mounting and brake illustrations. The tool section identifies both proprietary and dealer-made equipment, including the Matra 311 flywheel puller, Matra 529 clutch-centering arbor, shop-made 5042 final-drive tooth-play fixture, 5094 suspension compressor, 5096 neutral-contact gauge, and 5098/4 spoke-fitting gauge.

The ZIP also contains a separate 72-page July 2008 MOTORRAD STEMLER illustrated parts catalog and a 38-page August 2010 price list. The catalog supplies exploded component-group drawings, part-number callouts, replacement notes, and model-specific R26/R27 listings for the engine, transmission, carburetor, chassis, suspension, brakes, wheels, body fittings, and electrical equipment. These two files are later supplier references, not sections of BMW P/N 9099 136; the price list is a historical reference and should not be read as current pricing or availability.

Several cautions are especially important during repair. Rear swing-arm and wheel taper-roller bearing races and rollers must remain as matched sets; mixing them or leaving incorrect bearing play can compromise alignment and bearing life. R26 and R27 timing-chain installation uses different indexing methods, and applying the wrong method can put valve and ignition timing out of phase. During final-drive assembly, the seal lips require protection and the matched gear-set shim relationship must be restored; forcing the cover or ignoring the setup can damage seals and produce an incorrect tooth-contact pattern.

Engine, wheel, brake, steering, frame, and sidecar work directly affects safe vehicle operation. Use proper supports and personal protective equipment, isolate fuel and electrical systems where required, follow the complete manual procedure, and verify all braking, steering, wheel, and drivetrain functions before returning the motorcycle to service.