Positioning:
The Ski-Doo Alpine 640 was a versatile, utilitarian snowmobile designed for work, trail riding, and recreational use, often favored for its robust build and ability to handle varied snow conditions.
Competitors:
Competed with other utility and crossover snowmobiles from brands like Arctic Cat, Yamaha, and Polaris during the early 1980s.
Features:
Likely featured a reliable Rotax 2-stroke engine, a comfortable rider position, good cargo capacity (often with a rear rack or seat), and a robust chassis for durability.
Engine:
Detailed breakdown of the Rotax 640cc engine, including cylinder head, piston, crankshaft, lubrication system, cooling system, and ignition system.
Fuel System:
Carburetor(s) service, fuel pump, fuel lines, fuel tank, and related components.
Drive System:
Chaincase, primary clutch, secondary clutch, drive belt, and rear suspension drive components.
Electrical System:
Ignition system (CDI, ignition coil, spark plugs), lighting system, charging system (stator, rectifier/regulator), starting system (starter motor, battery), and wiring diagrams.
Suspension:
Front ski suspension, rear suspension (articulated or independent depending on exact sub-model), shock absorbers, and bushings.
Steering:
Handlebar assembly, steering column, tie rods, and ski steering mechanism.
Braking System:
Brake lever, brake cable, brake drum, brake pads (if applicable), and wheel hub assembly.
Chassis Body:
Frame inspection and repair, body panels, seats, windshield, and track system.
Track System:
Track inspection, tension adjustment, and replacement, idler wheels, and bogie wheels.
Scheduled Maintenance:
Oil changes, spark plug replacement, air filter cleaning/replacement, track tension adjustment, lubrication points.
Engine Repair:
Top-end rebuild (piston, rings, cylinder), valve adjustments (if applicable to 2-stroke design), crankshaft and bearing replacement, gasket replacement.
Carburetor Service:
Disassembly, cleaning, reassembly, jetting, and synchronization (if multi-carb).
Clutch Service:
Primary and secondary clutch inspection, cleaning, weight and spring replacement, and clutch alignment.
Electrical Diagnostics:
Troubleshooting ignition, charging, and starting system faults using test procedures and wiring diagrams.
Suspension Overhaul:
Shock absorber rebuilding or replacement, spring replacement, and bushing service.
Brake Adjustment And Repair:
Cable adjustment, drum brake servicing, and any hydraulic components if present.
Track And Skid Frame Repair:
Idler wheel and bogie wheel replacement, suspension arm alignment, and track replacement.
Troubleshooting Guides:
Systematic diagnostic flowcharts for common performance issues and component failures.
Depth:
Comprehensive, covering everything from basic pre-ride checks and routine maintenance to complete engine teardowns, clutch recalibration, and electrical system diagnostics.
Engine Type:
2-Stroke, Piston Port Induction (typical for Rotax engines of this era)
Displacement:
636 cc (or approximately 640 cc as per model name)
Configuration:
Vertical Twin-Cylinder (most likely configuration for this displacement)
Cooling System:
Fan Cooled
Horsepower:
Estimated 35-50 HP (specific output varies by tune and model year)
Torque:
Not explicitly specified but designed for good low-end torque for pulling power.
Carburetion:
Likely a dual carburetor setup (e.g., Mikuni VM Series or equivalent) for the twin cylinders.
Fuel Type:
Regular Unleaded Gasoline (typically mixed with 2-stroke oil, or equipped with oil injection)
Oil System:
Oil injection system or pre-mix (manual will specify the correct method).
Oil Change Interval:
Engine oil change (gearbox oil for 2-stroke crankcase) typically every 1,000-2,000 miles or annually. Manual will specify exact interval and type.
Spark Plug Replacement:
Recommended every 1,000-2,000 miles or as needed based on performance. Manual will specify plug gap and type.
Clutch Inspection:
Recommend inspection at 500-1,000 mile intervals for wear and performance.
Track Tension Adjustment:
Check and adjust track tension regularly, especially after initial break-in or track replacement. Manual will detail procedure.
Gearbox Oil:
Specific Snowmobile Gearcase Lubricant (e.g., SAE 80 or 85W-90, manual will confirm exact type and capacity).
2 Stroke Oil:
High-quality 2-stroke synthetic or semi-synthetic oil suitable for fan-cooled engines (e.g., API TC, JASO FD rated). Manual will recommend specific blend.
Coolant:
N/A (Fan Cooled)
Common Wear Items:
Clutch weights and buttons, drive and driven clutch springs, shock absorber bushings, steering tie rods, and track lugs.
Engine Specific:
Potential for carbon buildup in exhaust ports, wear on reed valves (if equipped), and carburetor jetting issues due to fuel variations or altitude. Manual covers proper cleaning and adjustment.
Chassis Specific:
Frame stress points, especially around suspension mounts, may require inspection. Track drive components (idler wheels, bogies) can wear.
