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1999 polaris sportsman 500

Discussion in 'Mechanic and Repair' started by KCL, May 26, 2009.

  1. KCL

    KCL LawnSite Member
    Posts: 61

    I have a 1999 polaris sportsman 500 with really low miles and hours. It recently started to knock when you get the rpms up. At idle it is fine. I runs perfect and starts fine. Any thought?
  2. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    Is it a top end or bottom end knock ?

    Is it knocking in neutral or under load (riding) ?

    The Sportsman has a speedo on it, How many miles/hours ?
  3. KCL

    KCL LawnSite Member
    Posts: 61

    Seems to be the top end. It knocks in nuetral and in drive. It has about 1000 miles

  4. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024


    You could check the valve clearances, Back in 98/99 they had some issues with exhaust cam lob wipe-outs. Also check the exhaust flange gasket for leaks and make sure the pipe springs are not stretched. The only other thing that comes to mind is a tear-down inspection, Remove the top end and check the wrist pin bearing and crankpin journal bushing.
  5. SLR

    SLR LawnSite Gold Member
    Posts: 3,218

    How old is gas in tank?
  6. KCL

    KCL LawnSite Member
    Posts: 61

    Not very old. I'm thinking maybe I need to run a higher octane
  7. AI Inc

    AI Inc LawnSite Fanatic
    Posts: 25,151

    My trucks drink regular , everything else ( Harley , boat 4 wheeler , snowmobile ) drink super.

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