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Discussion Starter #1
Hey guys, I have a Polaris sportsman 500 and I have had it since 2001 maybe. Last September it started to have a loss of power. It would have half power at half throttle and if you went any further at full throttle then it felt like it was bogging down or half throttle. My dad had a guy work on it then he didn't know what was wrong with it and we brought it to a dealership. My dad put $1000+ in it and still didn't have it fixed. I got it back home, in pieces(really crappy service), and started to put it back together and put a new sparkplug in it and it ran like new. I got brand new itp mud lite xl tires on the front and regular mudlite on the back and a superwinch lt 3000lb and it has started doing it again. It has new royalpurple motor oil in it. I have never replaced the air filter cause my dad said it didn't need one, I have covered food plots in really sandy south Ga. where it was dusty. I have been searching on google and found something about the cam and flatspots. When it was worked on the guy had a supposedly "great" mechanic look at it and said it was fine. The only thing I have done to it before is change all the fluids and new tires, starter( going on 2nd one), and a belt. And thanks for helping me diagnose the speedometer problem also. Any help is appreciated.
 

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For sure change the air filter. It should be done at every oil change. If I was your Dad I would get my 1000$ back. What did the " great mechanic" actually do besides take it apart? Try rebuilding the carb. I think the flat spots on cam was with the HO models.
 

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Discussion Starter #3
I will get an air filter. He rebuilt the carb. And he cant get his $1000 back, it was supposedly $70 an hour cause it was older than 10 years or something. He put a new stator on it and all kinds of stuff.
 

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Start with a new air filter, fuel filter, and a good thorough carb cleaning, and make sure the airbox is closed up good. The cam issues are on the early models 500's, pre 04 I believe. Yu could likely have a cam on it's way out too. But start with the easy stuff first.
 

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Discussion Starter #5
The guy I brought it to first changed the fuel filter, cleaned and rebuilt the carb, and their is a few holes in the lid of the box where the air filter is cause the bolts to bolt it down fell out.
 

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it sure does sound like the cam issue that ive read so much about. did anyone ever check the valve clearance? might be a good idea to set them. and do a compression check? if the 97 is the same as the 98 it used wingnuts to hold down the lid on the air cleaner, should be easy for u too replace the missing nuts? but that's not the issue! let us know the compression!
 

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Discussion Starter #7
I will talk to m dad and see if we can do a compression check and valve clearance. I cant replace the bolts on the air box, plastic it around them to hold them so you can screw the wing nut on. I tried to fill them with silicone but it was cold outside and I didn't do a very good job
 

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Pull the valve cover off and have a peek at the exhaust side of the cam. Its to the front of the bike.
Pretty sure this is a classic cam case, on the early 500's.
 

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Discussion Starter #9
When I got it back home their was a plate took off on top, to the front, and angled on the motor. They looked at everything.
 

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Sounds like bad cam to me too, check that first if that's not it could also be buttons worn out in secondary clutch, dirty carb ,ect.
 

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Discussion Starter #13 (Edited)
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