Spark Plugs

Content Source: 2019 850 PRO-RMK / SKS 155 Owner’s Manual (9928946 R01) > Maintenance Chapter

IMPORTANT

The Owner's Manual for this vehicle contains warnings, instructions and other information you must read and fully understand before safely riding or performing maintenance on this vehicle.Always follow the warnings and instructions in Owner's Manual.

Click the CONTENTS link above for the Table Of Contents, or download a full PDF of the Owner Manual in the Owner Support area of Polaris.com

Spark Plugs

Spark Plug Recommendations

NOTE

Using non-recommended spark plugs can result in serious engine damage. A spark plug with a heat range too high will always cause engine damage if the engine is operated in conditions more severe than intended for that plug. Always use the spark plugs recommended for your snowmobile.

A new engine can cause temporary spark plug fouling due to the preservative added during the assembly process. Avoid prolonged idle speeds, which cause plug fouling and carbonization.

Refer to the Specifications chapter for the specific spark plug to be used in your snowmobile.

Change the spark plugs at the intervals outlined in the Periodic Maintenance section.

Use recommended spark plugs with the proper gap. Refer to the specifications section for the specific spark plug to be used in your snowmobile.
Use only resistor-type spark plugs.

Torque spark plugs to specification.

TORQUE
18-22 ft. lbs. (24-30 Nm)

Always carry spare spark plugs.

Spark Plug Inspection

Spark plug condition is indicative of engine operation. The spark plug firing end condition should be read after the engine has been warmed up and the vehicle has been driven at higher speeds. Immediately check the spark plug for correct color.

WARNING

A hot exhaust system and engine can cause burns. Wear protective gloves when removing a spark plug for inspection.

Remove the left side panel and hood.
Remove the spark plug cap.
Using the spark plug wrench provided in the tool kit, rotate the spark plug counter-clockwise to remove it.
Reverse the procedure for spark plug installation. Torque to specification.
Reinstall the spark plug cap. Verify an “audible” click is heard when installing the plug cap.

Spark Plug Condition

Normal Plug

The normal insulator tip is gray, tan or light brown. There will be few combustion deposits. The electrodes are not burned or eroded. This indicates the proper type and heat range for the engine and the service.

TIP

The tip should not be white. A white insulator tip indicates overheating, caused by use of an improper spark plug or incorrect carburetor/throttle body adjustments.

Wet Fouled Plug

The wet fouled insulator tip is black. A damp oil film covers the firing end. There may be a carbon layer over the entire nose. Generally, the electrodes are not worn. General causes of fouling are excessive oil or use of non-recommended injection oil.