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Discussion Starter #1
So Id say about 2 years back I bought a 2013 Polaris Sportsman 500 H.O. off of my uncle. It ran perfectly, nothing wrong at all. I usually go mudding with it or just ride trails with buddies. So as you would assume, the quad is quite dirty from sitting for a few weeks.

STUTTERING PROBLEM: I noticed one day out of nowhere that in high gear at 15-20 MPH, I was already maxed out at 4500-5000 RPM It would get to 15-20 mph, max out on rpms and start sputtering. It sounded like it was basically acting like it couldn’t go any faster than this.

IDLING PROBLEM: I was fucking with the carberator the other day maybe thinking that is causing my sputtering, and now my idle will shoot up to 2600 on start usually, then I will turn the throttle adjustment down to the normal 1400. The rpms with then fluctuate 10-30 rpms back and forth repeatedly, it will then run for about another 30-60 seconds and the RPMs will slowly drop to about 900-1000 RPM and stall out. I replaced the carburetor and everything seems to be working perfect on that, no leaks and what not but it’s still acting strange. Also, I’ve noticed that when looking into the Electronic Throttle Control that two plates that aren’t supposed to touch have to be WAY past touching to even try to fire up. Even when set at a wide open throttle like that, I still have to give it some throttle to get it to fire up.

Here is what I have done so far:
Checked the belt and clutch
Changed out spark plug (Last one was covered in carbon)
Cleaned the intake and air box
Replaced the carburetor
Replaced the inline fuel filter
Checked that all lines on carburetor are connected into the right spots
Checked If intake boot was cracked (Not from what I can see)
Unhooked and reattached new carburetor (About 4-5 times)
Cleaned battery terminals and battery off
Shut on and off Gas Line Cutoff Valve

My next thoughts are that maybe the TPS is fucked up or maybe the Spark Arrestor is plugged with mud. I was thinking tomorrow to purge the exhaust and also check the ohms output on the TPS.


6,568 Posts
First, please edit the expletives in your post.

Second, you do not have a TPS (throttle position sensor) to adjust - there is a TSS (throttle safety switch) which is simply adjusted with the throttle cable.

One thing you have failed to do is check the valve adjustment. If you don't know when the last the valve clearance was checked, then it's over due. Keep in mind that carburetors do not usually cause 'sputtering' unless they are running rich. Most carb problems are related to running too lean especially on a vehicle using alcohol blended fuel and have set unused for more than two weeks. Most over rich conditions are related to dirty air filtration or obstructed air intake.

Although you put in a new spark plug, what brand of spark plug did you put in and what did you set the gap at?

Since the vehicle seeming ran fine one time then not the next time I would surmise the problem is something that changed with time or temperature. Valve clearance, fuel and spark plugs are the most common culprits that are time and temperature sensitive.
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