Segment:
Trail/Utility Snowmobile. The Indy 400 SKS was a popular model in Polaris's lineup, offering a balance of performance and versatility for recreational riders.
Competitors:
Competed with other 400cc class snowmobiles from manufacturers like Ski-Doo (e.g., Safari), Yamaha (e.g., Exciter), and Arctic Cat during the mid-to-late 1980s.
Features:
The SKS (Special Ski & Snowmobile) designation typically indicated a model optimized for deeper snow conditions or off-trail capability, often featuring a slightly longer track or improved suspension compared to standard Indy models.
Value:
Essential for owners seeking to perform maintenance, repairs, and diagnostics to keep their vintage Polaris Indy 400 SKS running optimally. Provides OEM-level information for accurate work.
Primary Coverage:
Full service, repair, and maintenance for the 1987 Polaris Indy 400 SKS snowmobile.
Estimated Pages:
Variable (typical factory service manuals range from 200-600+ pages; exact count not provided in product info).
Type:
Factory Service Repair Manual
Language:
English (Assumed, standard for Polaris manuals of this era).
Engine:
Detailed diagnostics, overhaul, component identification, specifications, and tuning for the 400cc class engine.
Fuel System:
Carburetor adjustment and cleaning (likely Mikuni VM series), fuel pump, fuel lines, and tank maintenance.
Ignition System:
CDI unit, stator, ignition coil, spark plug specifications, timing, and troubleshooting.
Cooling System:
Air cooling system details, fan, shroud, and maintenance.
Drive System:
Primary clutch (drive clutch) inspection, maintenance, and calibration; secondary clutch (driven clutch) assembly, adjustment, and belt replacement.
Suspension:
Front IFS (Independent Front Suspension) or trailing arm system, rear suspension (articulating or torque sensing), shock absorber service, and lubrication points.
Brakes:
Hydraulic disc brake system maintenance, fluid specifications, caliper service, and rotor inspection.
Electrical System:
Wiring diagrams, lighting, battery maintenance, starter system, and kill switch operation.
Chassis And Body:
Frame inspection, seat removal, hood and windshield maintenance, ski and track inspection.
Routine Maintenance:
Oil changes (if applicable for gearcase), lubrication points, spark plug checks, track tension adjustment, and general cleaning.
Engine Overhaul:
Piston and ring replacement, cylinder inspection, crankshaft and connecting rod checks, seal and gasket replacement.
Clutch Service:
Clutch alignment, weight and spring replacement, roller and bushing inspection, sheave cleaning.
Suspension Repair:
Shock absorber rebuilding or replacement, ball joint and tie rod end inspection, ski alignment.
Brake Maintenance:
Brake pad replacement, bleeding the hydraulic system, caliper seal replacement.
Electrical Troubleshooting:
Diagnosing starting issues, lighting failures, and ignition problems using provided wiring diagrams.
Troubleshooting Guides:
Systematic diagnostic flowcharts for common performance issues, starting problems, and component failures.
Depth:
Comprehensive (covers everything from basic maintenance to complete engine rebuilds and major component overhauls).
Compatibility:
Requires Adobe Acrobat Reader or compatible PDF viewer. Recommended for digital use, printing specific sections is possible.
Quality:
Digital PDF quality; clarity depends on the original scan quality, but factory service manuals are typically high resolution.
Type:
N/A (Digital PDF format, not a physical book).
Type:
N/A (Digital PDF format, not applicable).
Type:
Two-stroke, Twin Cylinder, Fan-Cooled
Displacement:
Approximately 398 cc (exact bore and stroke would be detailed in the manual).
Bore X Stroke:
Specifics to be found within the manual (e.g., 63mm x 64mm typical for this class).
Carburetion:
Likely a dual Mikuni VM34 or similar carburetor setup.
Horsepower:
Estimated 40-50 HP (typical for 400cc class two-strokes of this era; precise figure in manual).
Torque:
Specific figures to be found in manual.
Fuel Type:
Unleaded gasoline mixed with 2-stroke oil (pre-mix or oil injection system, manual will specify).
Oil Type:
Specific 2-stroke snowmobile oil viscosity and type (e.g., SAE 30 or 0W-30 synthetic, specified in manual).
Ignition Type:
CDI (Capacitor Discharge Ignition)
Type:
CVT (Continuously Variable Transmission) utilizing a centrifugal clutch (drive clutch) and a spring-loaded, adjustable clutch (driven clutch).
Options:
N/A (Standard CVT system for this model).
Gear Reduction:
Integrated chaincase for final drive reduction. Gear oil type and capacity specified in manual.
Clutch Calibration:
Manual provides specifications for clutch weights, springs, and helix angles for optimal performance based on application.
Certification:
N/A (Snowmobiles are not typically rated by organizations like NHTSA or IIHS). Adherence to manufacturer safety guidelines is paramount.
Safety Features:
Engine kill switch tether (operator presence control), brake system, headlight, taillight, reflector placement.
Design Considerations:
Chassis stability, track grip, handlebar steering response.
Clutch Inspection:
Recommended every 500 miles or annually: inspect drive and driven clutches for wear on sheaves, rollers, and bushings. Check belt condition and tension.
Engine Tune-Up:
Recommended annually or every 1000 miles: Inspect and clean/replace spark plugs, check carburetor synchronization and jetting, inspect air filter.
Lubrication:
Grease suspension fittings, steering components, and drive shaft bearings as per manual's schedule (typically annually or every 500 miles).
Chaincase Oil:
Specific gear oil viscosity and type (e.g., SAE 80W-90 GL-5 gear oil) and capacity will be detailed in the manual.
Brake Fluid:
DOT 3 or DOT 4 hydraulic brake fluid (specific type confirmed in manual).
Common Wear Items:
Drive belt wear, clutch roller wear, shock absorber seals, track lugs, ski carbides, and steering components can be common wear items on snowmobiles of this age.
Engine Carburation:
Carburetors can become clogged with age or poor fuel storage, leading to performance issues. Fuel stabilizers are crucial for storage.
Part Numbers:
The manual will contain OEM part numbers for all components, crucial for sourcing replacements for this vintage model.
Polaris Legacy:
Polaris has a long and storied history in snowmobiling, dating back to the 1950s. They are known for innovation and building durable, capable machines.
Indy Lineage:
The Indy line was a cornerstone of Polaris's snowmobile offerings, evolving significantly over the years. The 1987 models represented a mature design phase for the brand.
Era:
The mid-to-late 1980s was a competitive period in the snowmobile industry, with manufacturers focusing on engine refinement, suspension technology, and rider comfort.
