Yamaha BR250F / BR250 Bravo Snowmobile - Factory Service Manual Maintenance & Repair Reference 1981-1984

Yamaha BR250F / BR250 Bravo Service Manual - 1981-1984

This factory-authorized documentation establishes the definitive technical framework for the maintenance, diagnostic, and overhaul protocols of the BR250 series. Operational reliability is significantly enhanced by adhering to the specific carburetor synchronization and float height settings, which prevent lean-run conditions and ensure consistent thermal stability during high-load operation. Utilizing these factory-calibrated benchmarks ensures the machine maintains the safety and reliability standards established by the original system architecture.

Technical Applicability & Serial Ranges

The technical specifications and service procedures detailed in this manual are applicable to the following vehicle identification sequences:

• Model BR250F (Standard Configuration)
  • Frame ID Range: Starting at 8R4-000101
  • Engine ID Range: Starting at R246-000101
• Model BR250 Bravo (Commercial/Utility Variant)
  • Applicability: 1982 through 1984 production iterations featuring the 246cc fan-cooled power plant.

Systemic Reliability & Performance ROI

• Structural Integrity Verification: Verified torque sequences for crankcase and cylinder head fasteners eliminate the risk of primary compression leaks and casting deformation.
• Precision Fuel Calibration: Detailed jetting charts and altitude compensation tables allow for optimized combustion efficiency across diverse atmospheric conditions.
• Electrical System Diagnostics: Comprehensive testing procedures for the C.D.I. unit and lighting coils ensure electrical stability and prevent ignition failure in sub-zero environments.

Document Metadata

• Print Number: LIT-12618-00-41 (8R4-28197-10)
• Page Count: 166 Pages
• Document Edition: First Edition (Revised)

Technical Depth & Factory Benchmarks

System maintenance must strictly follow the factory-defined tolerances to ensure operational compliance. The R246 single-cylinder engine requires a precise piston-to-cylinder clearance of 0.045–0.050 mm (0.0018–0.0020 in) to mitigate the risk of thermal seizure while maintaining peak volumetric efficiency. Lubrication protocols demand the use of specific low-temperature lithium-base grease for chassis pivot points and molybdenum disulfide grease for the secondary shaft sliding sheave to ensure smooth torque sensing and shift response.

Visual Navigation Aids

Complex diagnostic paths and assembly sequences are supported by the following technical illustrations:

• Exploded View Geometry: Detailed schematic breakdowns for the Autolube oil injection pump and the centrifugal drive clutch assembly.
• Systemic Wiring Schematics: Full-color coded diagrams illustrating the ignition trigger path, lighting circuits, and emergency shut-off loops.
• Fluid Management Maps: Visual routing guides for the pulse vacuum lines and oil delivery hoses to ensure air-free lubrication.

Table of Contents

• General Information: Machine Identification, Storage Protocols, and Special Tooling Requirements.
• Engine: Top-end Overhaul, Crankshaft Alignment, and Autolube Pump Displacement Testing.
• Carburetion: Keihin BD32-28 Disassembly, Cleaning, and High-Altitude Calibration.
• Power Train: V-Belt Wear Analysis, Sheave Alignment, and Chain Case Gearing.
• Chassis: Steering Geometry, Ski Alignment, and Slide Rail Suspension Service.
• Electrical: C.D.I. Magneto Output Tests, Spark Plug Heat Range Analysis, and Troubleshooting.

Operational Limits & Specifications

Adherence to the following factory specifications is mandatory for structural and mechanical validation:

• Cylinder Head Torque: 2.5 m-kg (18 ft-lb) in a cross-pattern sequence.
• Primary Drive Sheave Bolt: Initial seating at 10 m-kg (72 ft-lb); Final retighten at 6.0 m-kg (43.5 ft-lb).
• Autolube Pump Stroke: 0.20–0.25 mm (0.008–0.010 in) at minimum throttle.
• Spark Plug Gap (NGK BR8HS): 0.6–0.7 mm (0.024–0.028 in).
• Track Tension: 25–30 mm (1.0–1.2 in) deflection at 10 kg (22 lb) load.