Results 1 to 5 of 5
  1. #1

    Unhappy Superjet top end rebuild.. is my crank still good?? Please help me!

    Hey all, ive had my 2000 superjet for about a month now, shes been going absolutly awesome! my compression is down to 150/143psi tho.. the last owner never rebuilt and said he's used it least an hour a week for the last 10 years! thats around 300+ hours on it!
    so while the weather is cold down here in aus, thought I'd take the time to rebuild the top end!

    pullerd my cylinder block and took it down to my local machining shop to get bored and honed .5mm bigger.. thats was a couple days ago.. tonight i thought I'd pull out the pistons and get it ready for my block back after the weekend.. this is what I discovered!

    The missing piece of the piston is gone too!
    There are scratch marks under around the crank shaft where obviously the piece of the piston has been pushed around the crank housing!

    So obviously the previous owner has opened it up, taken out the piece of piston fromt eh crank, slapped her bak together and sold it.. to me!

    When i move the conrods around and spin the crank, im hearing a fairly noisy rolling sound, not really a grinding sound tho.. im just wondering if this is normal or might I need to take the whole motor out and replace the big end bearings or something??

    Ive uploaded a video with sound of me spinning the crank.. its 2.5MB tho.. couldnt figure how to compress it further.. but i really need a professional opinion on what else I may need to fix/rebuild and the cost im up for!
    I was hoping to go on a big jetski trip next weekend!

    here's the video!

    Any comments or suggestions would be greatly appreicated!!

  2. #2
    any ideas on cost options would be good too!
    thanks in advance!

  3. #3

    Join Date
    Jul 2010
    Morehead City, NC
    If it was me, and the crank had been running OK to this point, I'd probably run it until it locked up. You do, however, risk damage to the crank preventing re-build. On the other hand, you can spend $300 and get a rebuilt stock crank with new bearings. It depends on your budget! The previous owner might not have pulled that piece out, btw. It may have gotten chewed up by the rotating assembly. I suppose it doesn't really matter at this point

  4. #4
    banshee350racer's Avatar
    Join Date
    Oct 2008
    I would pull the motor inspect the rest of it. Right now your only seeing 1/2 the motor. I understand budget has a lot to do with it. Say that piece wasnít removed now itís chewed up and in your bearings! If you do slap it back together ďas isĒ and locks up or the bearings fail in time, it may blast a hole in the side of the case then you will need an entire motor. New cases, crank, maybe even cylinders, pistons, head who knows the extent of the damage if it blows apart. Just take a step back look at your budget and motor. If you canít afford it now save up and do it right. Otherwise it will cost you more in the end if you donít do it right the first time. Who knows you might already need a new bottom end depending on what happened to the piston skirt. good luck

  5. #5

    Join Date
    Jun 2008
    St Clair Shores, MI
    I'd put a crank in it. Especially if you can get a rebuilt one for a few hundred bucks.

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. Top End Rebuild Help
    By hopeful1 in forum Yamaha Old School Skis
    Replies: 2
    Last Post: 03-19-2009, 07:37 PM
  2. Top End Rebuild
    By Stoffa17 in forum 2-Stroke Performance
    Replies: 2
    Last Post: 01-03-2008, 04:40 PM
  3. top end rebuild costs?
    By izz0 in forum Yamaha Open Discussion
    Replies: 6
    Last Post: 07-24-2007, 02:33 PM
  4. '96 SL780 top end rebuild
    By repoman in forum Polaris Open Discussion
    Replies: 25
    Last Post: 06-23-2007, 12:49 AM
  5. '96 SL780 top end rebuild
    By repoman in forum Polaris Open Discussion
    Replies: 7
    Last Post: 04-08-2007, 09:47 PM

Posting Permissions

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