Model:
Bonneville 750 & Tiger 750
Body Styles:
Roadster (Bonneville), Dual-Sport/Scrambler (Tiger)
Production Years Covered:
Primarily 1973-1983 (Bonneville T140V/TSX/ES/D, Tiger TR7)
Historical Context:
Iconic British motorcycles known for their parallel-twin engines, distinctive styling, and a strong presence in classic motorcycle culture.
Contemporary Rivals:
Competed with other large-displacement twins from Japanese manufacturers (e.g., Honda CB750, Kawasaki Z1) and other British marques.
Bonnevile Appeal:
Classic styling, smooth parallel-twin power delivery, comfortable riding position.
Tiger Appeal:
More rugged and versatile, suited for off-pavement excursions with its higher ground clearance and often knobbier tires.
Target Audience:
Owners, restorers, and mechanics working on Triumph Bonneville 750 and Tiger 750 motorcycles.
Engine:
Full overhaul, disassembly, reassembly, tuning, carburetor servicing (e.g., Amal Concentric), ignition system (points, coils), lubrication system.
Transmission:
Gearbox servicing, clutch replacement, chain drive maintenance, gearbox oil specifications.
Chassis:
Frame inspection, suspension (forks, rear shocks), steering head bearings, wheel bearings, spoking, tire fitting.
Brakes:
Front and rear brake systems (typically Grimeca or Triumph disc brakes, drum brakes), hydraulic fluid, caliper servicing.
Electrical System:
Wiring diagrams, lighting systems, battery maintenance, charging system (alternator/generator), starter motor, ignition timing.
Fuel System:
Fuel tank servicing, fuel lines, fuel taps, carburetor tuning and synchronization.
Bodywork:
Fender removal, seat mounting, tank mounting, minor bodywork adjustments.
Maintenance:
Scheduled maintenance, lubrication, filter changes, spark plug replacement, chain adjustment.
Troubleshooting:
Diagnosis of common running issues, electrical faults, and mechanical problems with symptom-based guidance.
Repair:
Step-by-step instructions for component removal, overhaul, and reinstallation.
Diagnostics:
Guidance on identifying and rectifying common performance and reliability issues.
Depth:
Comprehensive, covering everything from basic servicing to full engine rebuilds and electrical system diagnostics.
Type:
Air-cooled, parallel-twin, four-stroke
Bore X Stroke:
76 mm x 81.5 mm
Compression Ratio:
Typically 8.5:1 to 9.5:1 depending on specific model variant.
Horsepower:
Approx. 50-55 bhp at 6,500-7,000 rpm
Torque:
Approx. 45-50 lb-ft at 4,000-5,000 rpm
Carburetors:
Twin Amal Concentric (or similar, e.g., Mark II) 30mm or 32mm carburetors
Fuel Type:
Unleaded petrol (recommendations for lead-free adapters or hardened valve seats if original) or leaded petrol.
Type:
Contact breaker points ignition, or early electronic ignition on later models.
Crash Safety:
N/A (Motorcycles of this era did not undergo standardized crash testing like modern cars).
Brakes:
Disc brakes (front, typically single disc), drum brakes (rear on some models, later models featured dual front discs on T140D/ES variants).
Lighting:
Headlight, taillight, brake light, turn signals.
Oil Change:
Every 3,000 miles or annually, whichever comes first.
Valve Adjustment:
Every 6,000 miles (or as specified in manual for checking clearance).
Spark Plug Check:
Every 6,000 miles.
Chain Lubrication Adjustment:
Every 500 miles or after washing/rain.
Engine Oil Capacity:
Approx. 2.5 liters (5.3 US pints) for 750cc models (confirm with manual).
Engine Oil Type:
SAE 20W-50 motorcycle oil (mineral based recommended for this era).
Brake Fluid:
DOT 3 or DOT 4 hydraulic brake fluid (confirm specific type in manual).
Carburetion:
Amal carburetors can be prone to wear and require periodic adjustment/rebuilding for optimal performance. Jetting may need recalibration for altitude or fuel changes.
Oil Leaks:
Common with motorcycles of this age; check and replace worn gaskets, O-rings, and seals (e.g., primary cover, cylinder base).
Electrical Reliability:
Wiring can degrade over time; check connections, stator/generator output, and regulator/rectifier for consistent voltage.
Gearbox Clutch:
Clutch plates can wear; gearbox dogs and shift forks can wear with high mileage, potentially leading to false neutrals or difficulty engaging gears.
Tappets:
Valve clearances can widen, requiring adjustment to prevent noise and potential damage.
Triumph Legacy:
Triumph is one of the oldest motorcycle manufacturers, with a rich history of innovation and performance dating back to the early 20th century.
Bonnevile Lineage:
The Bonneville name originated in the 1950s and became synonymous with high-performance British motorcycles, evolving through various engine sizes and configurations.
Tiger Lineage:
The Tiger name historically represented Triumph's off-road and adventure-oriented models, with the TR7 representing a modern interpretation of this concept in the 1970s.
Manufacturing Era:
This generation of 750cc twins was produced during a challenging period for the British motorcycle industry, with significant changes in ownership and manufacturing practices.
Key Variants:
T140V (1973-74), T140R (Roadster), T140E (Economy, emission controls), T140ES (Electric Start), T140D (Special, disc brakes front and rear), TR7 (Tiger).
