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Discussion Starter #1
My 2011 Sportsman 850 X2 has less than 200 hrs. It has started backfiring when letting off the throttle. Besides trying a new plug where else should I look to solve the problem.
 

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you may need a valve adjustment....there was a post simular here where the problem was the same...he adjusted valves and cured it....
 

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I suggest that first of all, adjust your throttle cable

Have a good day
Mariano
 

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Spark plugs!
 

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New air filter and plugs first.

Sent from my SCH-R970 using Tapatalk
 

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Make sure your throttle cable is tight. Not too tight though, should have about 1/8" of play in the throttle if I remember correctly.
 

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The correct procedure to adjust the throttle cable is the following

Electronic Throttle Control Switch (ETC) /

Throttle Cable Adjustment





1. Slide the boot back far enough to expose the inline cable

adjuster sleeve and loosen the adjuster locknut.

2. Remove the (4) screws and cover from the RH control.

3. With handlebars centered and wheels pointing forward,

slowly turn the adjuster sleeve counter-clockwise (out) just

until the gap is removed between the throttle arm and the

throttle arm stop (see illustration below).

NOTE: While moving the adjuster sleeve, “flip” the

throttle lever slightly to remove slack in the cable.



4. Turn the cable adjuster sleeve clockwise (in) 1.5 - 2 turns;

tighten locknut and reinstall boot. After this adjustment

there should be .079-.118” (2-3 mm) gap between throttle

arm and throttle arm stop.




5. Reinstall the RH control cover and ensure the O-ring is

properly in place. Securely tighten the (4) screws.

6. Place the vehicle in PARK and start the engine. Turn the

handlebars from full left to full right while listening for any

change in engine speed. If engine speed changes, loosen

the locknut and turn the adjuster sleeve clockwise (in) an

additional 1/2 turn and repeat this step.
 

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Mine has also been backfiring a 2013 850xp with 21 Hours.
 

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Mine backfired a lot but quit when it had around 1000 miles on it. I think the computer is programmed to run rich for a certain period of time when new, during break in. Just my thoughts on it.
 

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Had the same problem. The bolts had come loose from the intake flange to the head. Check the bolts are tight and the gasket is good. If not, take the bolts out and put some blue Locktite on the threads before reinstalling them.
 

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Discussion Starter #11
Thank you for the help. The plugs and air filter were fine. The throttle cable adjustment did the trick, it had become loose underneath the rubber sleeve. What do the contact points inside the throttle mechanism control? The engine is very sensitive to the connection breaking contact before any increase in RPM occurs or the check engine light will come on. When decelerating, it seems like a very fine line for those contacts to close at the right time or else you get backfires. Thanks again.
 

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My 2012 still backfires every now and again under certain conditions. Mainly when I abruptly let off the throttle going down hill. Already adjusted the throttle cable, I figure it'll work itself out once I get some more hours on it. It's barely broken in as it is.
 
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