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Old 10-11-2010, 09:58 AM
harley rider's Avatar
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500 sportsman boggs and misfires

I got a 2003 sportsman 500 SE. It starts and idles fine but when you give about 1/8 feeder the motor boggs and misfires. In reverse it almost dies out but when I activate the overdive button it improves but not enough. The plug seems good, the TPS on the bar has 1/8 clearence. I drained the carb bowl and all seamed fine. Tomorrow when the stores are open I will pick up a new plug and fuel filter. Any other ideas??
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Old 10-11-2010, 05:47 PM
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Mr. Harley Rider.

I am new to Polaris and just bought a used 1996 Sportsman 500 with the same problem as you describe. From the little research I have done. Polaris ATV engines use the same technology for years. Some say it's rock solid, some say it's junk. My machine has 800 miles on it and the cam is wore out already. The exhaust lobes are gone. Here is a video of my machine running. does your machine sound like this?
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Old 10-11-2010, 06:29 PM
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Quote:
Originally Posted by Mrgearhead View Post
I am new to Polaris and just bought a used 1996 Sportsman 500 with the same problem as you describe. From the little research I have done. Polaris ATV engines use the same technology for years. Some say it's rock solid, some say it's junk. My machine has 800 miles on it and the cam is wore out already. The exhaust lobes are gone. Here is a video of my machine running. does your machine sound like this? YouTube - 1996 Polaris Sportsman 500 runs bad. Help! What am I missing.wmv

never done any work to my polaris yet, but from what i have worked on, it sounds like your carb needs some new jets and needles... carb kits are cheap on these motors.
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Old 10-13-2010, 02:59 AM
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Well the spark plug and filter didn't help anything. So I removed the carb and the rubber intake boot. There is some dry cracking on it, so a new one will be installed later today. Also found the needle and seat worn, so new on of those also. It would cause excessive fuel in bowl. Leaving for hunting on Friday so want the damn machine running strong.
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Old 10-21-2010, 05:23 AM
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Quote:
Originally Posted by Mrgearhead View Post
I am new to Polaris and just bought a used 1996 Sportsman 500 with the same problem as you describe. From the little research I have done. Polaris ATV engines use the same technology for years. Some say it's rock solid, some say it's junk. My machine has 800 miles on it and the cam is wore out already. The exhaust lobes are gone. Here is a video of my machine running. does your machine sound like this? YouTube - 1996 Polaris Sportsman 500 runs bad. Help! What am I missing.wmv
My 1999 sportsman does the same , I did renew the carb, played with ignition timning , rev limiter ,checked the valves and finally taken of the cylinder head off and suprise: camshaft worn out , intake valves partly worn out and springs how to say gone too soft .
Now I am waiting for parts to be send to me . As soon as I put the engine together I will let you know the out come.
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Old 11-23-2011, 02:38 PM
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500 misfire problem

I see it's a long time since anyone wrote in this thread, but has anyone found a solution? My '98 500 does the exact same thing, when running at more than 3/4 throttle, it starts caughing out the carb and misfiring. I have had the cylinder head off and rebuilt it with new cam, lifters, springs, valves, you name it, and I had high hopes for this, but it did not work. I have played with the carb, cleaning it out several times, making the mix leaner and richer, but no luck. By coincidence, I started it without the air filter box, and then it ran even at higher revs, but it blew out of the carb. I have tried adjusting the timing (cam) in both directions, no luck. I have also adjusted the ignition timing, no luck... The spark plug is new, but I will try to replace it again for another brand (think it is Champion sitting there now, so it should be good stuff). I will also try to run a higher octane fuel (I'm from Norway, and we still have 98 octane at the pumps here :-) ) I'm running it at 95 octane now, but my idea is that higher octanes require higher compression before it ignites. I've done quite a bit of research on the web, and this seems to be a common problem, so SOMEONE must have found a solution. Please help, I'm desperate!!!
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Old 11-23-2011, 03:46 PM
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Check the ETC (electronic throttle control) make sure you don't have too much slack in your throttle cable. Check spark plug gap & make sure its correct plug. Exaust system air leak. Air leak in intake (check intake boot for cracks), make sure air box lid is sealed. Could also be a faulty coil.
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2011 Sportsman 500 H.O. Green
14" STI Wheels-26" Mud Trax X/L's
2500# polaris winch
Ricochet a-arm guards
Rev. override kit
Hid 3 light kit
3 light mod. w/relay

Uni air filter on both

Wifes
2011 Sportsman 500 H.O. Red
Ricochet a-arm guards
Hid 3 light kit
3 light mod. w/relay
Winch,wheels & tires still to go!
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Old 11-24-2011, 02:11 PM
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Thanks for your tips. During my research before rebuilding the head, I checked both the ETC and the speed limiter, timing and a bunch of other stuff, but no luck... I will double check the spark plug gap, and also the other things you mention, like throttle cable slack, and intake leak. The thing is that (from all the research I have done to date) these engines run OK if you take off the air box. I did that, and it ran OK, but it was pushing air/exhaust/gas out through the carb. When I put on only the rubber "duct" going from the carb to the air box, the same thing happened; it started caughing/bogging/misfiring. It's like it pushes this mix out through the carb and into the duct, and when the engine tries to "breath" in fresh air/fuel, it is only breathing in what it just pushed out and then does not have enough fresh air to run correctly. Anyway, I will try some of the tips you gave, and keep on trying other things as well. I also contacted Polaris today asking for a solution. If I get a good response, I will for sure post it here, because I know this is a common problem for these engines. Thanks, though, and any other tip is also highly appreciated.
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Old 11-25-2011, 02:56 AM
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I had the same problem on my 500 1999 model, try to do all sorts of stuff , ignition timing, valve clerance, rebuild the carb no luck finaly i did replace the camshaft and rocker arms (in take and exhaust).
Please check the camshaft lobes , rocker arms (the exhaust one) and you will see that exhaust lobe and rocker arm one can be slightly worn out .
This is causing the problem also please check the automatic compression mechanism if is working correctly .
If you need more help , please write me a message .
Zyggi
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Old 11-25-2011, 03:13 AM
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Quote:
Originally Posted by NorthernPolarisRider View Post
but it was pushing air/exhaust/gas out through the carb. When I put on only the rubber "duct" going from the carb to the air box, the same thing happened; it startedcaughing/bogging/misfiring. It's like it pushes this mix out through the carb and into the duct, and when the engine tries to "breath" in fresh air/fuel, it is only breathing in what it just pushed out and then does not have enough fresh air to run correctly.
I know you totally rebuilt the head but it sounds like a intake valve might be sticking open a little!
__________________
2011 Sportsman 500 H.O. Green
14" STI Wheels-26" Mud Trax X/L's
2500# polaris winch
Ricochet a-arm guards
Rev. override kit
Hid 3 light kit
3 light mod. w/relay

Uni air filter on both

Wifes
2011 Sportsman 500 H.O. Red
Ricochet a-arm guards
Hid 3 light kit
3 light mod. w/relay
Winch,wheels & tires still to go!
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