Page 1 of 2 1 2 LastLast
Results 1 to 10 of 16
  1. #1

    Join Date
    Aug 2009
    Location
    LI, NY
    Posts
    344
    +1
    3

    98 760xl burn't piston

    Got it apart after losing speed and rpm. Rear piston melted front looks ok. Totally stock ski with 104 hours. Still using oil injection and it was definetly working. What are the other possible causes to this problem? Where to look for a service manual?


  2. #2
    if you got pics it would help to determine the cause. burnt piston is typically a lean condition air leak. fuel volume or pressure low from a bad pump or restriction. you may have a bad crankshaft seal.

  3. #3
    dghal's Avatar
    Join Date
    Jul 2008
    Location
    League City Texas
    Posts
    280
    Quote Originally Posted by desertdeweller View Post
    if you got pics it would help to determine the cause. burnt piston is typically a lean condition air leak. fuel volume or pressure low from a bad pump or restriction. you may have a bad crankshaft seal.

    I concur,

    What were you doing when it blew up?

    running wide open? pulling a tube?

    was the engine fully warmed up

    new gas or old gas? what octane gas.

    oil injection was working? how so? no line blockage.

    have you had it for all 104 hours?

    what heat range spark plugs?

    many things can cause a melt down,,

    post some pictures of the damaged parts.

  4. #4

    Join Date
    Aug 2009
    Location
    LI, NY
    Posts
    344
    +1
    3
    Running at various speeds over 2 days noticed drop in rpm not pulling tube. New 87 octane fuel warmed up.Oil injection working lines were not blocked. Purchased with 70 hours on it and put on remaining 34 hours. Using ngk br8hs spark plugs. Will post pics asap.

  5. #5

    Join Date
    Aug 2009
    Location
    LI, NY
    Posts
    344
    +1
    3
    Here are pics.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	piston burnt.JPG 
Views:	71 
Size:	3.29 MB 
ID:	148548  

  6. #6

    Join Date
    Aug 2009
    Location
    LI, NY
    Posts
    344
    +1
    3
    Sorry second pic
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	burnt piston.JPG 
Views:	75 
Size:	3.24 MB 
ID:	148551  

  7. #7
    Xl760 on the water/ gp760 in shop for paint
    Join Date
    Jun 2008
    Location
    Ontario, Canada
    Posts
    88
    Thats not a burnt piston, looks like the piston broke on the exhaust side and scored the piston, any marks or pits on the dome of the head??

  8. #8

    Join Date
    Aug 2009
    Location
    LI, NY
    Posts
    344
    +1
    3
    Yes head is badly pitted from piston material.

  9. #9

    Join Date
    Aug 2009
    Location
    LI, NY
    Posts
    344
    +1
    3
    Just got it all apart and front piston is just starting to melt on exhaust side the same as rear piston.

  10. #10
    Here come the smokers! OBXJeepGuy's Avatar
    Join Date
    Aug 2008
    Location
    Outer Banks, NC
    Posts
    1,393
    That exact same thing happened to my 760 last year....

Page 1 of 2 1 2 LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. 1995 Polaris SLT 750 - burned middle piston
    By irishfred in forum Polaris Open Discussion
    Replies: 6
    Last Post: 10-03-2011, 07:01 PM
  2. Will a clogged CAT CONV burn a piston?
    By Voodoo121 in forum Yamaha Open Discussion
    Replies: 13
    Last Post: 07-13-2008, 10:38 AM
  3. My 98 xl1200 piston wash pics
    By Insanediego Joe in forum Yamaha Old School Skis
    Replies: 13
    Last Post: 09-23-2007, 12:03 PM
  4. problem burning hole in piston
    By matthew1 in forum Polaris Open Discussion
    Replies: 7
    Last Post: 08-03-2007, 07:02 PM
  5. Slt 750 Burning Holes In Front Piston
    By 2sl750 in forum Polaris Open Discussion
    Replies: 11
    Last Post: 07-17-2007, 02:00 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •