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  1. #1

    disintegrated ring land on top groove of piston #3

    In checking the compression on my 1999 SLTX 1050 the back 2 cyliders where low #1 120, #2 90, #3 60
    So I proceeded to do a tear down & inspect
    what I found was a Broken ring land on top of piston #3 plus the cylinder wall is pretty scored up
    piston #2 doesn't look to bad but there is quite a bit of slop between the piston & the cylinder plus some scoring in the cylinder wall
    in looking at the top of the pistons they appear to be stock & not oversized: listed on top 1, 80-85

    wondering if this is just normal wear & tear for this old of a watercraft?
    or if there was some kind of mixture related issues or problems to cause the piston failure
    plus I'm wondering what brand pistons would be the best way to go for replacements
    WSM, wiseco, etc...
    should the carbs be rebuilt or checked out, etc...

    Thanks
    Last edited by carms_us; 02-16-2009 at 10:07 AM. Reason: improper wording


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Welcome to the Hulk!

    You can find the Polaris Factory Service Manuals here. We don't have the 1999 manual online, but the 1992-1998 manual should cover most 1050 engine related info.

    If you can post some clear close up photos of the pistons and cylinder walls, we may be able to provide some insight into the cause of the damage. To post photos, reply using Advanced Mode, scroll down to Manage Attachments.

    Any time you have to do engine work, you should clean and rebuild the carbs.

    In fact, being ten years old, you should go through the entire fuel and oil systems. New fuel hoses would be good, replace the fuel and oil filters. Replace the oil lines while you are at it. Clean and refurb the fuel selector valve.

    What grade of gasoline have you been using? Was it old fuel?

    How long have you had this machine?
    What is the service history?

    How many engine hours?

  3. #3

    Loss of compression, Piston failure, Rebuilding top end of engine, etc...

    Soon as I get a chance I'll take some pictures & post them along with more specifics about the watercraft, engine hours, it's past, etc...

    Thanks for your response

  4. #4
    SPEED KILLS, BUT YOU GET THERE QUICKER Keddano's Avatar
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    If the ring land is broken and not burnt,then it is normally from a ring hanging in a port. Could be caused by excessive wear in the cylinder,allowing piston rock,as mentioned on the other piston,how many hours? or could be a overbore with a stock piston,or something got ingested into the cylinder(sorta hard if the FA's are in place,unless it was a choke screw)

  5. #5

    Pictures of piston failure

    Here's some pics piston #2 & #3
    looks like I could have did a better job of taking the pictures
    but hopefully they are legible enough to determine problem
    #1 piston still looks to be in pretty good shape
    yes there was quite a bit of slop or excessive wear in the rear 2 cylinders seemingly progressive from front of engine to rear cylinder
    The watercraft was bought used so we don't know to much about it's past
    Did a visual of the rear crank seal but looks ok by sight, also in looking at #3 base gasket looks like it might have been leaking or blown
    wondering if the gasket or the rear seal might be leaking possibly causing a lean condition
    anyone know if either are common problems for this model watercraft?
    Thanks
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  6. #6
    SPEED KILLS, BUT YOU GET THERE QUICKER Keddano's Avatar
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    That piston was ran lean,Looking at the top of the piston there is no Wash Pattern at all. That motor doesn't have any inherent problems,no more then any others. If your going to rebuild it,Go completely thru it,All new seals,check the crank bearing,Rebuild the carbs,Etc.Seals can go bad and leak,Carbs can get plugged,hoses can deterate.....Etc. Others will chime in also.

  7. #7
    Lake Mead Bum & BTLS Mark starflight's Avatar
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    Are all domestic pistons like that? The top ring that close to the dome? The fugis have alot more meat above the top ring.

  8. #8
    SPEED KILLS, BUT YOU GET THERE QUICKER Keddano's Avatar
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    I'd like to see higher resilution pictures of the broken,burnt edge. I can't tell by the picture if that is broken or burnt. If someone has took out the back cylinders in the past,they may have just been honed a few times,leaving them with excessive clearance.

  9. #9

    Higher resolution picture piston #3

    Here's a bit closer picture of piston #3
    Looks like the ring land disintegrated

    I'm thinking it was a base gasket failure for that cylinder which could have also influenced piston #2
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  10. #10
    SPEED KILLS, BUT YOU GET THERE QUICKER Keddano's Avatar
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    It does look as if it's broken,As much scoring on the sides as there is,A air leak is a good possiblity.If the piston ran lean and heated,it may have expanded to the point to catch the port.Any sign of damage to the port ?

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