LockedPictures of Sportsmans common cam problem.

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2001sportsman400
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2011/02/07 16:24:10 (permalink)

Pictures of Sportsmans common cam problem.

This seems to be a problem with the sportsmans. The exhaust lobe on the cam wears off. I think that my carb float neeedle and seat being worn out caused this. I noticed that I had fuel in my air box. Drained it and didnt think anything else of it. Put a new needle and seat in it. Turns out that about 3 weeks later I realized gas had also filled my motor and diluted the oil so much it was like water. I also noticed it had very tiny sparkles in it. Messed with the carb thinking I had a clogged jet. Read somewhere someone said to check the exhaust lobe on the cam. Finallly popped the valve cover and found  a bad cam. Here are pics of the cam and the exhaust rocker arm. Both are trashed.


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    whalebus
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    Re:Pictures of Sportsmans common cam problem. 2011/02/07 16:55:36 (permalink)
    when you fix it make sure the oiul passages oer cleaned out so it want happen again
    #2
    J_Fred
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    Re:Pictures of Sportsmans common cam problem. 2011/02/07 17:58:32 (permalink)
    What kind of oil are you using?
     
    This is a common problem for those that do not use the recommended oil, not for the 400 and 500 engines.

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    #3
    2001sportsman400
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    Re:Pictures of Sportsmans common cam problem. 2011/02/07 18:20:32 (permalink)
    J_Fred

    What kind of oil are you using?

    This is a common problem for those that do not use the recommended oil, not for the 400 and 500 engines.

     
    Did you read what I wrote? Or did you just comment on the pic? The oil was diluted with gas.............I will never buy into the idea that only polaris oil is suitable for a polaris engine. Thats propaga, believe it if you will.................I was running mobile synthetic.
    #4
    Dezz
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    Re:Pictures of Sportsmans common cam problem. 2011/02/07 18:25:34 (permalink)
    This is not a common problem with the 400 or 500 Polaris engines.
    This would be problem with engines period knowing the details of why it happened. Running any engine on thinned oil can/will cause excessive wear, especially in the camshaft lobe areas. Not using a recommended oil can also lead to this.
     
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    #5
    whalebus
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    Re:Pictures of Sportsmans common cam problem. 2011/02/07 18:59:23 (permalink)
    I aree on you can use differnt oil if you want but even with thinned out oil the cam should not have scared like that un less there was lack of oil.the if the oil was that thin that this happened the the rod and main bearings would be toast and the rings fried.just my .02   there are issues with early sportsman 500 exhuast loab wearing out and stopped up oil galleys if you google it.Just saying if your that deep into it I would definatly pull the head and give it a look over.good luck
    #6
    2001sportsman400
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    Re:Pictures of Sportsmans common cam problem. 2011/02/07 19:17:16 (permalink)
    Yep, that makes good sense. The other 2 lobes and rockers look find. I have also been told that it has something to do with the aluminum oil tank and stuff settling in the bottom then, being pumped and clogging stuff up. Have heard switching to the new plastic oil tank would fix it.  It has never had burnt up oil in it. Other than this recent gas problem. Once the oil started changing colors I have always changed it. I am inclined to think something was clogged as has been suggested by several people now.
    #7
    The Goat
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    Re:Pictures of Sportsmans common cam problem. 2011/02/07 19:26:31 (permalink)
    The oil in my sig is what I recommend for all quads not revving to the moon.

    Always looking for trx70 and atc 70.
    #8
    2001sportsman400
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    Re:Pictures of Sportsmans common cam problem. 2011/02/07 19:26:45 (permalink)
    Then, again thinking about it........The exhaust rocker arm has twice the spring pressure pushing on it as the intake valves do. The intake valves have one spring per valve where as the exhaust valve has 2 springs on it . I would think thin oil with twice the spring pressure would cause it to fail twice as fast as the intake lobes would due to heat. Heat would be an issue on the exhaust valve with gas thinned oil way before it would the intake valves. But, I will check and make sure it was getting proper lube to it.
    #9
    J_Fred
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    Re:Pictures of Sportsmans common cam problem. 2011/02/08 15:51:15 (permalink)
    Run whatever oil you want.  The engines are made with 0w-40 in mind.  Running different oils may/may not hurt. 
     
    This is what you said:
    "This seems to be a common problem with the Sportsmans. The exhaust lobe on the cam wears off.".
     
    That makes it seem as if you think the cam wearing down prematurely is a common problem for the Sportsmans (I honestly don't know any other way to read it).  It is not, as long as everything is up to spec and the proper fluids are used.  Your follow up description does a good job of detailing the entire problem, but saying the cams wearing down is "common'' is misleading information.  This isn't helpful to the Polaris community as a whole.
     
    Anyway, sorry for the bad luck, seems like you are on your way to getting it back running 100%.  Good luck.

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    #10
    2001sportsman400
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    Re:Pictures of Sportsmans common cam problem. 2011/02/08 16:51:24 (permalink)
    Well this isnt the ONLY forum for polaris. I have read threads on different forums and several people have had this problem with their sportsmans. Sorry if you are offended by the fact that this has indeed happened before on several Polaris quads. I dont care if you did or didnt use PROPER fluids. It gets mixed with enough gas it isnt gonna do its job. Why isnt pictures and a discription of what is going on not helpful to the polaris community?  If you dont agree with the thread or dont have helpful info for me do us both a favor dont click on it.  Makes me kind of think you took what I have posted personel. If so, SORRY................. From here on out I will referr to it as a possible problem. I tried to change the orginal post  to avoid further confusion but, I cant. 
    post edited by 2001sportsman400 - 2011/02/08 17:08:37
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    bigpopo2792
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    Re:Pictures of Sportsmans common cam problem. 2011/02/08 21:02:25 (permalink)
    I know many people that run mobile 1 synthetic and yamalube with no problems at all so its not so much as using the PROPER fluids as it is changing it at the CORRECT time. the older sportsman's, non HO's, had soft profile cams that prematurely wore out if the oil was not changed frequently or if the oil passages were clogged.  either way running the bike with gas in the oil is never a good thing lol

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    jeff
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    Re:Pictures of Sportsmans common cam problem. 2011/02/10 09:46:01 (permalink)
    2001sportsman400

    Then, again thinking about it........The exhaust rocker arm has twice the spring pressure pushing on it as the intake valves do.

    Ding, ding, ding.....we have a winner. 
    Yes it is a known problem on the 500's, but often time with other factors contributing.  I know 2 people personally that this has happened to in the past year.  One bike was a 01' H.O. and the other a older Non H.O. Ranger.  The Ranger was though to have worn out from years of farm service and probably a combination of poor maintainance.  The Sportsman....not really sure on that bike.  He only ran polaris oil and kept up with it pretty well but it was a mud bike so who knows.

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    J_Fred
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    Re:Pictures of Sportsmans common cam problem. 2011/02/10 10:03:36 (permalink)
    jeff

    2001sportsman400

    Then, again thinking about it........The exhaust rocker arm has twice the spring pressure pushing on it as the intake valves do.

    Yes it is a known problem on the 500's, but often time with other factors contributing

     
    Exactly : Outside factors.  So the cam prematurely wearing for no real reason, or in a defect in and of itself, doesn't seem to be common.  That's what I have heard, and was getting at.  Proper fluids, and no extraneous problems, the cam shouldn't wear prematurely.
     



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    poo_850
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    Re:Pictures of Sportsmans common cam problem. 2011/02/10 13:51:32 (permalink)
    so.. are you gona use it as a good reason to buy a aftermarket "performance" cam
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    jeff
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    Re:Pictures of Sportsmans common cam problem. 2011/02/10 14:11:02 (permalink)
    ^ Nope.  If is a non HO put a HO cam in it.  If its a HO than just replace with the same cam.

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    2001sportsman400
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    Re:Pictures of Sportsmans common cam problem. 2011/02/10 20:26:02 (permalink)
    Its a 400. Not a 500 but, the 500 non HO and the 400 use the same cam. The 450HO and the 500HO use the same came but bigger carb. I am wondering why would not be able to get a 40mm carb and a HO cam. You boys think that would work?
    post edited by 2001sportsman400 - 2011/02/10 20:27:20
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    poo_850
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    Re:Pictures of Sportsmans common cam problem. 2011/02/10 20:36:28 (permalink)
    **** ya it will work, but dont expect to just bolt it on and work youl have to jet it right which is a simple task , btw a 450 sportsman uses a 34mm carb
    post edited by poo_850 - 2011/02/10 20:50:22
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    jeff
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    Re:Pictures of Sportsmans common cam problem. 2011/02/10 21:38:20 (permalink)
    Yeah a 34-36mm would be perfect for that 400 even with the ho cam. I think a 40mm is too big for a 400. What size is on that 400 now?

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    poo_850
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    Re:Pictures of Sportsmans common cam problem. 2011/02/10 21:44:21 (permalink)
    as far as i know it is still a 34, and i think the 400 will handle a 40 mm carb throw a k&n air filter on and maybee even a exhaust it will roast alot of 500's jmo
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    2001sportsman400
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    Re:Pictures of Sportsmans common cam problem. 2011/02/11 05:29:36 (permalink)
    Well, it has the 34mm on it now. The 450 from reasch is basically a stroked 400. Its got a 500 crank in it with a 400 rod and piston. With this combo the cc's bump from 425 to like 450. I think I am gonna go with the HO cam kit and look for a HO carb. See what happens.
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    jeff
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    Re:Pictures of Sportsmans common cam problem. 2011/02/11 06:58:25 (permalink)
    Oh ok so your 400 is actually a 425? I didn't know that. I knew they made the 425 before the 500. Always wondered why they would have dumped it then make a 400 and 450.

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    bf500efi
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    Re:Pictures of Sportsmans common cam problem. 2011/02/11 11:12:25 (permalink)
    i've chatted with a few people that had older 500s that had the cam lobs wear out, but they had a whole bunch a miles on em. No matter what, the 500 is still the best motor to ever come out of Polaris. Very low maintenance, Tough as nails and can last forever if taken care of. I got 3000 miles on mine and i believe it runs stronger now than the day i bought it new. 

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    jeff
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    Re:Pictures of Sportsmans common cam problem. 2011/02/11 12:06:33 (permalink)
    bf500efi
    No matter what, the 500 is still the best motor to ever come out of Polaris.

     
      I'll drink to that.  Definantly the most reliable, and as you said tough as nails.


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    2001sportsman400
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    Re:Pictures of Sportsmans common cam problem. 2011/02/11 13:50:54 (permalink)
    My odometer quit working when it was about 4 years old. It had of 2000 on it then. Its been a tough quad.
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