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Hello everyone. New to the forum here and hoping to get some advice from my fellow ATV enthusiasts. I have a 2013 Polaris Sportsman 400 that I've had for about 6 months now. Last month, it started bogging down and losing power when going up hills, and I couldn't get it to go much faster than 30 or 35 mph on a straightaway. Almost sounded like it was hitting a governor. I read on one of these forums that it is most likely the carb, so I got a Dynajet carb kit, thoroughly cleaned the carb, and re-jetted using a 160 as specified for my elevation. I replaced the fuel filter and the spark plug. I swapped out the OEM air filter for a K&N. Got everything back together today and took it for a spin around the block. It seemed to run fine in low gear, but the top end in high just isn't there. I can only get it up to about 30 mph with full throttle. The carb re-jetting helped with the popping noise and the bogging down (it was really bad before. Like 5 mph up a steep trail in low with full throttle bad) but I can't get the power out of it that I used to. Any ideas? Appreciate any input!

Paul
 

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I would check your belt, could be worn
 

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What are your RPM's when the machine is at top speed (30mph)?
 

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Also, did you check for water in the belt case?
 

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Also, did you check for water in the belt case?
I replaced the belt. The old one didn't look too bad, but I will follow the break in procedure carefully for the new one. No water in the belt case. Clean and dry. How do I check the buttons? Also, where does the vac line from the very bottom of the carb connect to? I think this may be part of the problem lol. It was just laying there. Must have forgotten to re-connect it upon re-installation of the carb.
 

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What are your RPM's when the machine is at top speed (30mph)?
The RPM's are right around 4500 give or take a hundred. This is at about 25 mph. When I pull the choke out, the RPM's go almost to 5000 and the speed increases a bit. Here are my thoughts, and please check me on this. When I drilled out the brass plug inside the carburetor to adjust the fuel/air mixture screw, perhaps I adjusted the screw wrong. I went with a 160 jet (Dynajet kit) and it said to screw the screw in all the way and then back it out three turns. I assumed this meant three whole turns, so that's what I did. Perhaps when I re-hooked up the choke cable to the carb, I didn't set the play in the choke cable correctly. The one screw holds the cable in the carb, and the other adjusts the tension, I believe. Do you know how I check the secondary clutch? I had the cover off today and replaced the belt to no avail. I've heard many people having problems with the secondary clutch, but I don't know enough about them to know what I was looking for. Any thoughts? Thanks all!
 

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How many miles on the 400? Are you running larger mud tires? Just trying to establish the amount of wear on the clutches. It sounds like you are getting power out of the engine and carb with the amount of rpm it's pushing. I'm still leaning toward the clutches.
 

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How many miles on the 400? Are you running larger mud tires? Just trying to establish the amount of wear on the clutches. It sounds like you are getting power out of the engine and carb with the amount of rpm it's pushing. I'm still leaning toward the clutches.
There are about 17o hours on it with 1365 miles.
 

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Discussion Starter #10
So I screwed the fuel/air mixture screw in all the way until it seated and then I backed it out two turns instead of the three I had it set to before. I'm talking the one inside the carb that was originally covered with a brass plug. I drilled out the brass plug when I installed the Dynajet kit. Not much difference in top end. I did notice, however, that there is a small amount of fuel coming out of the little line on the bottom of the carb (the one with the check valve). Is this a sign that it is running too rich? If you're still leaning toward the buttons on the secondary clutch, do you have any sources (videos, write-ups, etc.) that I could use as a reference to swap the buttons? I've never messed with the clutches before. Thanks in advance.
 
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