The 1986 Polaris Indy 400 carburetor manual provides comprehensive service information for the Mikuni VM34 carburetor system used on the 1986 Polaris Indy 400 snowmobile. This manual covers carburetor specifications, adjustment procedures, troubleshooting, maintenance schedules, and repair instructions for optimal engine performance in various temperature and altitude conditions.
Key components: Mikuni VM34 carburetor, throttle cable assembly, fuel inlet fitting, choke mechanism, jet needle assembly, float bowl.
| Component | Specification |
|---|---|
| Carburetor Type | Mikuni VM34 round slide |
| Main Jet | #210 (standard) |
| Pilot Jet | #40 |
| Needle Jet | Q-2 |
| Jet Needle | 6DH4-3 (clip position 3) |
| Throttle Valve | 2.5 |
| Float Height | 21mm ± 1mm |
| Fuel Inlet | 1/8" NPT |
| Choke Type | Enrichment circuit |
| Air Screw | 1.5 turns out (initial setting) |
Remove old carburetor and install new unit following proper procedures.
WARNING! Fuel is flammable; work in well-ventilated area away from ignition sources.
Proper carburetor adjustment is critical for optimal engine performance.
CAUTION! Engine must be at operating temperature for accurate adjustments.
Carburetor features multiple adjustment points for precise fuel mixture control.
Adjustment Points: Idle speed screw, air mixture screw, main jet, pilot jet, needle clip, float bowl.
Idle Circuit: Controls fuel mixture at idle and low throttle openings. Main Circuit: Controls fuel mixture at 3/4 to full throttle. Needle Circuit: Controls fuel mixture at 1/4 to 3/4 throttle. Choke Circuit: Provides rich mixture for cold starting. Float System: Maintains consistent fuel level in float bowl.
Proper fuel system connections ensure reliable carburetor operation.
Tip: Always use fresh fuel and clean fuel filter for optimal performance.
Regular maintenance ensures reliable carburetor performance.
WARNING! Use only compressed air for jet cleaning; never use wire or drills.
Carburetor tuning for specific riding conditions and altitudes.
| Condition | Main Jet | Pilot Jet | Needle Position |
|---|---|---|---|
| Sea Level to 3000ft | #210 | #40 | 3 (middle) |
| 3000-6000ft | #200 | #35 | 2 (leaner) |
| 6000-9000ft | #190 | #30 | 1 (leanest) |
| Cold Weather (-20°F to 20°F) | #220 | #45 | 4 (richer) |
| Hot Weather (60°F+) | #200 | #35 | 2 (leaner) |
Proper cleaning prevents carburetor issues and ensures reliable operation.
Use carburetor cleaner and compressed air for thorough cleaning. Soak metal parts in carburetor cleaner solution. Blow out all passages with compressed air. Inspect rubber components for deterioration. Replace worn gaskets and O-rings.
CAUTION! Do not soak plastic or rubber components in carburetor cleaner.
This manual contains proprietary information for the 1986 Polaris Indy 400 carburetor system. All specifications and procedures are based on factory service data. Copyright © 1986 Polaris Industries Inc. For technical support, contact Polaris Customer Service at 1-800-POLARIS or visit www.polaris.com.
| Symptom | Possible Cause | Corrective Action |
|---|---|---|
| Hard starting | Clogged pilot jet, improper choke | Clean pilot jet, verify choke operation |
| Poor idle | Clogged idle circuit, air leak | Clean idle passages, check manifold gaskets |
| Bogging acceleration | Lean needle setting, clogged main jet | Adjust needle clip, clean main jet |
| High fuel consumption | Rich jetting, leaking float needle | Lean jetting, replace float needle |
| Engine flooding | Stuck float, contaminated needle seat | Clean float bowl, inspect needle and seat |
| Poor high speed performance | Clogged main jet, restricted airflow | Clean main jet, check air filter |
Reset: Return all adjustments to factory specifications if troubleshooting fails.
Service: 1-800-POLARIS; www.polaris.com