Polaris Sportsman 850 Idles Too Low


My 2009 Polaris Sportsman 850 engine runs too slowly while out of gear. It runs poorly after startup and at normal operating temperatures.

When the engine is warmed up the idle is less than 1100 rpm. What should the engine idle speed be set at for a 2009 Sportsman XP 850?

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Derek Shibuya 3 years 2020-12-02T21:26:15+00:00 3 Answers 1205 views Beginner 2

Answers ( 3 )


    The factory engine idle speed setting is 1200 ± 50 RPM. Check the following conditions if the Sportsman 850 idles poorly:

    Idle Too Low

    Symptom: The all-terrain vehicle is said to have a low idle when the engine rpm is less than 1100. Possible low idle causes include:

    • Blockage at the air filter.
    • Leaking injector (rich condition).
    • Belt dragging.
    • Disconnected wiring or faulty sensor.
    • Throttle stop screw was altered.

    The throttle body stop screw is preset from the factory. There is a tamper proof cap that covering the throttle stop screw. Do not make alterations to the throttle stop screw as the it controls the throttle body air flow calibration.

    Erratic Idle

    Erratic idle is when the machine runs irregular or in an uneven pattern while disconnected from a load. The most common causes of erratic idle include:

    • Misadjusted throttle cable.
    • Air leaks, dirty/clogged injector.
    • Throttle position sensor TPS faulty or misadjusted.
    • Valve too tight.
    • Belt dragging.
    • Air cleaner covered in too much dirt, soot or debris.
    • Low compression.
    • Worn engine components.
    • Fouled spark plugs.
    • Disconnected wiring or faulty sensor.

    Idle Too High

    Idle too high is when the Polaris Sportsman 850 idles too fast or above 1400 rpm while at normal operating temperature. The most common reasons for idling high are:

    • Throttle stop screw factory setting was altered.
    • Throttle cable misadjusted or sticking.
    • Intake air leak.
    • Disconnected wiring or faulty sensor.
    • Idle air control valve stuck or inoperative.


    My Polaris 850 XP had rough and it was sneezing out the exhaust, it was also stalling intermittently. I tried adjusting the throttle cable that runs down the handlebar but it didn’t fix the idle problem. I took off the throttle cover and adjusted the throttle switch and now it idles fine.

    Best answer

      My 2001 Polaris 425 xpedition was doing the same thing as in your video. I had already changed the fuel pump, lines and put a new carb on. Took the throttle cover off and sure enough the spring was laying loose inside. I fixed it and now it runs great! Thanks.

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