Page 1 of 2 1 2 LastLast
Results 1 to 10 of 16
  1. #1
    canuck's Avatar
    Join Date
    May 2006
    Location
    The wet left coast.
    Posts
    1,089
    +1
    108

    96 GTX Seized the PTO piston WHY is the big question ?

    The background

    The ski is bone stock.

    Complete engine rebuild with rebuilt crank and counterbalancer shaft, bored with new ProX pistons and OEM gasket kit, .055 squish. Fuel tank removed and cleaned, pickup screen cleaned, new fuel lines, separator cleaned, carbs rebuilt with Mikuni kits.

    First ride about 2 hours no problems and I ran some oil premixed with the first tank of fuel. Second ride about 1.5 hours with some full throttle for a few seconds heading back to the ramp at about 3/4 throttle it died. Fired right up then died a few seconds later.

    After tear down the PTO piston had seized. The only reason I could find is the manual calls for the high speed screws to be closed on the MAG and 1/2 open on the PTO, I had them both closed. I can fix the damage where do I go to find the cause ? Would the closed high speed screw do this ?

    I'll post some pics tomorrow when the jugs come off.


  2. #2
    If i knew,...I wouldn't ask sea-one's Avatar
    Join Date
    Aug 2009
    Location
    Dallas/Waxahachie
    Posts
    2,340
    +1
    109
    The Infamous "lean" 3/4 throttle phomeonon strikes again..

  3. #3
    canuck's Avatar
    Join Date
    May 2006
    Location
    The wet left coast.
    Posts
    1,089
    +1
    108
    Quote Originally Posted by sea-one View Post
    The Infamous "lean" 3/4 throttle phomeonon strikes again..
    Why, what causes this ?

    Should I be making some jetting changes over the stock settings ?

  4. #4
    If i knew,...I wouldn't ask sea-one's Avatar
    Join Date
    Aug 2009
    Location
    Dallas/Waxahachie
    Posts
    2,340
    +1
    109
    i dont know,i've read and heard of this for years,Theres and article on SEA-DOO.net site.PPG performance talks of it.

  5. #5
    canuck's Avatar
    Join Date
    May 2006
    Location
    The wet left coast.
    Posts
    1,089
    +1
    108

    Pics

    Pics
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	IMG_5426.JPG 
Views:	64 
Size:	54.5 KB 
ID:	242680   Click image for larger version. 

Name:	IMG_5430.JPG 
Views:	72 
Size:	40.6 KB 
ID:	242679   Click image for larger version. 

Name:	IMG_5431.JPG 
Views:	78 
Size:	34.1 KB 
ID:	242681   Click image for larger version. 

Name:	IMG_5424.JPG 
Views:	69 
Size:	54.5 KB 
ID:	242682   Click image for larger version. 

Name:	IMG_5428.JPG 
Views:	52 
Size:	51.5 KB 
ID:	242683   Click image for larger version. 

Name:	IMG_5425.JPG 
Views:	60 
Size:	52.7 KB 
ID:	242684  

    Click image for larger version. 

Name:	IMG_5429.JPG 
Views:	69 
Size:	44.5 KB 
ID:	242685  

  6. #6
    canuck's Avatar
    Join Date
    May 2006
    Location
    The wet left coast.
    Posts
    1,089
    +1
    108
    Oil pump has been tested and works fine, using Amsoil Interceptor.

    Carbs have been apart again and are spotless nothing in the filters and the pop off is 28 psi on both carbs.

    Looking at the jetting specs and settings in the manual the 96 specs show both HS screws closed and the 97 specs show closed on the mag and 1/2 open on the PTO. Interesting since the 96 and 97 are mechanically identical machines. I'm going with 1/2 on the mag and 3/4 on the pto as I would rather be fat and happy rather than sticking pistons every second ride. After a few tanks I can do some plug chops and slowly close the highs.

    Engine will get pressure tested once assembled.

    Any other advise or input much appreciated.

  7. #7
    Doesn't look like it was getting much oil. What do the tops of the pistons look like? Plug color? Compression before it seized?

  8. #8
    canuck's Avatar
    Join Date
    May 2006
    Location
    The wet left coast.
    Posts
    1,089
    +1
    108
    Quote Originally Posted by Seapoo View Post
    Doesn't look like it was getting much oil. What do the tops of the pistons look like? Plug color? Compression before it seized?
    Left is PTO
    Right is MAG

    The PTO cylinder had more residual oil in it than the Mag cylinder.

    Sorry no pics of the piston tops as they are already at the machine shop. The MAG piston had a normal looking brown wash on top the PTO piston was black and oily.

    No compression numbers, it only had 3 1/2 to 4 hours run time on new ProX pistons.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	IMG_5434.JPG 
Views:	90 
Size:	46.9 KB 
ID:	242867  

  9. #9
    Were the carb filters cleaned?

  10. #10
    canuck's Avatar
    Join Date
    May 2006
    Location
    The wet left coast.
    Posts
    1,089
    +1
    108
    Quote Originally Posted by Seapoo View Post
    Were the carb filters cleaned?
    Yes both carbs rebuilt with Mikuni kits, I took the carbs apart last night to see if anything got in there and the filters looked like new nothing in them.

    I'm curious if the high speed screws being closed would do this ?

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. Why is the reverse on the right side??!!
    By SeaDoocer in forum Yamaha Open Discussion
    Replies: 7
    Last Post: 10-20-2007, 02:12 PM
  2. Why is the center carb tuned differently?
    By Metal4130 in forum Yamaha Old School Skis
    Replies: 4
    Last Post: 07-26-2007, 10:13 AM
  3. why oh why is the uk so s..t for cane owners
    By z00m in forum Polaris Open Discussion
    Replies: 4
    Last Post: 07-01-2007, 10:11 AM
  4. Why is this GTX SC so slow?
    By Shibby1485 in forum 4-Tec Performance
    Replies: 15
    Last Post: 05-24-2007, 08:41 PM
  5. Replies: 11
    Last Post: 11-04-2006, 03:41 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
  •