1988 Polaris Indy 400 Manual

The 1988 Polaris Indy 400 is a high-performance snowmobile featuring a 398cc air-cooled twin-cylinder engine, Polaris Variable Ratio (PVR) suspension, slide rail rear suspension, and manual reverse. This manual covers safety precautions, specifications, operation, maintenance, troubleshooting, and storage procedures for optimal performance and longevity.

1. Features at a Glance 2. Installation & Setup 3. Specifications 4. Controls and Operation 5. Maintenance Schedule 6. Engine System 7. Suspension & Drivetrain 8. Electrical System 9. Storage & Winterization 10. Safety Information 11. Troubleshooting

Features at a Glance

Key components: 398cc twin-cylinder engine, PVR front suspension, slide rail rear suspension, manual reverse, mechanical disc brake.

Feature	Description
Engine	398cc air-cooled twin-cylinder
Carburetion	Dual VM34 Mikuni carburetors
Front Suspension	Polaris Variable Ratio (PVR)
Rear Suspension	Slide rail with torsion springs
Track	15-inch wide rubber track
Brake System	Mechanical disc brake
Reverse	Manual reverse system
Fuel Capacity	11.5 gallons
Dry Weight	Approx. 425 lbs
Instrumentation	Speedometer, tachometer, fuel gauge

Installation & Setup

Pre-delivery inspection and setup procedures.

Remove shipping materials and inspect for damage.
Install handlebars and secure with provided hardware.
Check and adjust track tension to specification.
Fill with recommended 2-stroke oil and premium fuel.
Check tire pressure and suspension settings.

WARNING! Always wear safety gear during operation. Never operate under the influence of alcohol or drugs.

Specifications

Engine: 398cc air-cooled twin-cylinder 2-stroke
Bore x Stroke: 68mm x 55mm
Compression Ratio: 7.0:1
Carburetion: Dual VM34 Mikuni
Ignition: CDI electronic ignition
Starting System: Electric and pull start
Drive System: Polaris Variable Ratio (PVR)
Track Length: 121 inches
Suspension Travel: Front 7 inches, Rear 9 inches
Fuel Capacity: 11.5 gallons
Oil Capacity: 3 quarts

Controls and Operation

Main controls: Throttle lever, brake lever, choke, reverse lever, ignition switch.

Starting Procedure: Turn fuel valve on, set choke, pull starter rope or use electric start. Allow engine to warm up before riding.

Operation: Use throttle for acceleration, brake lever for stopping. Engage reverse only when completely stopped. Monitor instruments for proper operation.

Maintenance Schedule

Interval	Service Required
Every Ride	Check fuel and oil levels, inspect for damage
100 Miles	Check track tension, inspect drive belt
500 Miles	Change spark plugs, check carburetor settings
1000 Miles	Inspect suspension components, check brake system
Seasonal	Full inspection, lubrication, storage preparation

Engine System

398cc air-cooled twin-cylinder engine maintenance procedures.

Spark Plugs: Replace with NGK BR9ES every 500 miles
Carburetor Adjustment: Set idle speed to 1500-1700 RPM
Fuel Mix: Use premium unleaded gasoline with Polaris 2-stroke oil
Cooling: Ensure cooling fins are clean and unobstructed
Compression: Check compression regularly (should be 120+ PSI)

Suspension & Drivetrain

PVR front suspension and slide rail rear suspension maintenance.

Track Tension: Adjust to 1-1.5 inches of free play
Suspension Lubrication: Grease fittings every 200 miles
Drive Belt: Inspect for wear and proper alignment
Skis: Check for wear and proper alignment
Rear Idlers: Inspect bearings and replace if worn

Electrical System

CDI ignition, lighting, and starting system maintenance.

Battery: Maintain proper fluid levels, keep terminals clean
Spark: Check for strong blue spark at plugs
Lights: Inspect headlight, taillight, and brake light operation
Wiring: Check for damaged or loose connections
Stator: Test output if starting or charging problems occur

Storage & Winterization

Proper storage procedures for off-season.

Drain fuel system or add fuel stabilizer
Fog engine through spark plug holes
Remove battery and store in cool, dry place
Clean entire snowmobile thoroughly
Store on stands to relieve suspension pressure
Cover with breathable fabric to prevent moisture

CAUTION! Never store with fuel in carburetors without stabilizer.

Safety Information

Critical safety precautions for operation and maintenance.

Always wear DOT-approved helmet and protective clothing
Never operate on public roads or restricted areas
Check local laws and regulations before riding
Maintain safe following distances from other vehicles
Be aware of changing weather and trail conditions
Carry emergency supplies and communication devices

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	Fuel, spark, or compression issue	Check fuel supply, spark plugs, compression
Poor performance	Clogged carburetor, worn drive belt	Clean carburetor, inspect and replace belt
Overheating	Clogged cooling fins, lean fuel mixture	Clean cooling fins, check carburetor settings
Electrical failure	Battery, stator, or wiring issues	Test battery voltage, check stator output
Suspension problems	Worn components, improper adjustment	Inspect and lubricate, adjust to specifications

Service: Contact authorized Polaris dealer for major repairs

Parts: Use genuine Polaris parts for optimal performance