Page 1 of 4 1 2 3 ... LastLast
Results 1 to 10 of 34
  1. #1
    Cliffy's Avatar
    Join Date
    Oct 2009
    Location
    UK,
    Posts
    566

    Mullered Piston, Whats caused it?????????? More Pic's

    Guys

    Went out on my ski today, still not holding its idle though

    Went for a run doing 42 on the MFD then it died, started back up low speed back in, pulled the ski out of the water done some checks, pulled the spark plug and found a carboned up plug on the front mag (near steering)

    Here's what i found when i removed the heads


    Middle mag


    Rear mag


    Was it running to lean to cause that damage??, it hasnt damaged the bore so im guessing id get away with just a new piston and ring?? and gaskets??

    Is this a easy job, what should i be checking to ensure it doesnt happen again?

    Thanks
    Neil
    Last edited by Cliffy; 07-04-2010 at 06:53 PM.


  2. #2
    I think everyone is going to say a lean condition. Have you done all the upgrades? It looks like it was trying to burn a hole.

  3. #3
    Cliffy's Avatar
    Join Date
    Oct 2009
    Location
    UK,
    Posts
    566
    yeah i figured as much,

    It has a triple pump, checked and clean the carbs a while back, set all carbs to stock position last weekend, run wicked took it out today and this happened, deep joy

  4. #4
    Are you running premix? If so I think you need to richen up the mixture since oil displaces fuel. If you are not, I bet the mag carb was not rich enough.

  5. #5
    Cliffy's Avatar
    Join Date
    Oct 2009
    Location
    UK,
    Posts
    566
    na im still letting the ski do the mixing as it works well (well i thought it was)

    So now im gonna get 1 new piston, can i get a stock one as the bore doesnt have any major scoring maybe a light score in one place but not deep or anything u wouldnt feel the mark unless u used ur finger nail but again its very slight nothing major

  6. #6
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
    Join Date
    Oct 2006
    Location
    Cleveland OH
    Posts
    17,329
    +1
    30
    Major bummer.....

    Cen is pretty rich. the PTO doesn't look lean either.

    Something is restricting fuel flow to the MAG, or you had an air leak.

    Check your carb filters and make sure to do a leak down test after you replace the piston.

  7. #7
    Cliffy's Avatar
    Join Date
    Oct 2009
    Location
    UK,
    Posts
    566
    Quote Originally Posted by xlint89 View Post
    Major bummer.....

    Cen is pretty rich. the PTO doesn't look lean either.

    Something is restricting fuel flow to the MAG, or you had an air leak.

    Check your carb filters and make sure to do a leak down test after you replace the piston.
    Tell me about it buddy, whats a leak down test???

    Will i get away with a stock piston and ring??

    Also Pulling the cylinder pot off, will this give me enough access to the piston pin etc

    Any tips or tricks??

    Thanks again
    Neil

  8. #8
    Cliffy's Avatar
    Join Date
    Oct 2009
    Location
    UK,
    Posts
    566
    Quote Originally Posted by xlint89 View Post
    or you had an air leak.
    would that be from a cylinder ring brake down or something else??

  9. #9
    Cliffy's Avatar
    Join Date
    Oct 2009
    Location
    UK,
    Posts
    566
    Has anyone got any good pic's for a tear for this job??

  10. #10
    Clayton G's Avatar
    Join Date
    Apr 2009
    Location
    Upper Peninsula of Michigan
    Posts
    143
    Hello Cliffy

    No, an air leak meaning that the cylinder is pulling in air from somewhere other than the carb. This air doesn't have gas in it, so it leans air from the carb and burns pistons. Check around the cylinder base gaskets, the gaskets for the reeds and intake manifold and the gaskets under the carbs. Also look for any cracks in the manifold or any other possible spots that would leak.

    Check your fuel line to that carb, and the carb itself for any restrictions in fuel flow.

    Good luck,
    Clayton G

Page 1 of 4 1 2 3 ... LastLast

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. Swapped out my reeds today and found this, what caused it you think?
    By thetolleyman in forum Yamaha PWC Performance (2-stroke)
    Replies: 2
    Last Post: 09-18-2013, 07:07 AM
  2. GPR cylinder blew...dunno what caused it
    By 9t8gp1200 in forum Yamaha Old School Skis
    Replies: 7
    Last Post: 08-18-2010, 07:31 PM
  3. Think i found what caused my piston burn down.
    By xplayer2885 in forum Polaris Open Discussion
    Replies: 5
    Last Post: 06-28-2010, 09:43 PM
  4. What caused this Piston Damage - Ultra 150
    By hotshotbz in forum Kawasaki PWC Performance (2-stroke)
    Replies: 14
    Last Post: 01-27-2010, 04:26 PM
  5. Drive Shaft Noise: What Causes it?
    By thompsdw in forum Sea Doo Open Discussion
    Replies: 3
    Last Post: 08-18-2008, 11:08 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
  •