Page 1 of 2 1 2 LastLast
Results 1 to 10 of 18
  1. #1

    98 to 1200 motor question

    I have a 98 gp 1200 and a piece of one of the pistons cracked off. It did a little damage to the cylinder. Is it possible to just bore out the one cylinder or do you have to do all 3. It is stock right now. Is there anything else you would reccomend while I have the motor apart. New rings? On the other two. Any help would be much appreciated.
    Justin


  2. #2
    pilo704's Avatar
    Join Date
    Jul 2008
    Location
    dirty jerzz
    Posts
    830
    hey justin, you ask if you would have to do all three because you want to run 2 different bores? you can resleave the 1 one damaged cylinder..

  3. #3
    Yes, I was wondering about the two different bore sizes. Two cylinders would be stock. I called the local ski shop here and they said it would be $50 to bore the one cylinder. Then they said to buy a piston kit.

  4. #4
    jdog800's Avatar
    Join Date
    Feb 2007
    Location
    Alexandria L.A.
    Posts
    812
    as long as you cant catch your fingernail in the scratchs or damage to cylinder then it has to be bored. You can bore up to 86mm with the 65u engine.
    If your damage is deeper than that you will have to have it resleeved which will be stock bore if you go that route.
    I wouldnt recommend to anyone who was going the performance route to run with different size bores but for the average joe, haveing one piston slightly bigger (as long as you can go to the next bore) wont hurt. I have seen many boats run with this type setup and last for years. Especialy the old boats when they start going to the way side and you just dont want to spend a bunch of money on it.You dont gain very much displacement and the wieghts of the pistons are not enough difference to cause much torrsioning.
    The best route to go is to bore all three cylinders to buy all new pistons to match. This will improve power slightly and the motor will run smoother. This is better on the crank as well.
    gp1200 is one of the easyest and cheapest watercraft to mod so you can go as far as you want from here.

  5. #5

    couple more questions ?

    I really appreciate everyones help with this. Does anyone know what a piston kit and gaskets on average would go for? I would like to do all of the cylinders to repair it right. The local shop said $50 to bore the one cylinder I didn't think that was to bad? Am I right?
    Thanks Justin

  6. #6
    jdog800's Avatar
    Join Date
    Feb 2007
    Location
    Alexandria L.A.
    Posts
    812
    bore - 50. each
    pistons 100. to 145. each
    gasket set 100.

    think you buy this stuff in a kit for around 435.00 comes with pistons, gaskets, wristpins, rings and clips.

  7. #7
    Mpeavler's Avatar
    Join Date
    Dec 2005
    Location
    Anderson, Indiana
    Posts
    5,154
    +1
    170
    JD,
    I can in my set up run larger then 86mm....I believe I can actually run a few more bores beyond that ....from what I'm told ... from Mark? Although I don't see anything larger then 86mm that I can remember?

    M

  8. #8
    krispaintballz's Avatar
    Join Date
    Sep 2007
    Location
    Kenosha, WI
    Posts
    2,978
    Quote Originally Posted by Mpeavler View Post
    JD,
    I can in my set up run larger then 86mm....I believe I can actually run a few more bores beyond that ....from what I'm told ... from Mark? Although I don't see anything larger then 86mm that I can remember?

    M
    I think you can do 89mm on the sleaves you got mike.

  9. #9
    Mpeavler's Avatar
    Join Date
    Dec 2005
    Location
    Anderson, Indiana
    Posts
    5,154
    +1
    170
    Quote Originally Posted by krispaintballz View Post
    I think you can do 89mm on the sleaves you got mike.
    Yup...that's what Mark said...your right...I knew it was something crazy

  10. #10
    krispaintballz's Avatar
    Join Date
    Sep 2007
    Location
    Kenosha, WI
    Posts
    2,978
    Quote Originally Posted by Justin GP1200 View Post
    I really appreciate everyones help with this. Does anyone know what a piston kit and gaskets on average would go for? I would like to do all of the cylinders to repair it right. The local shop said $50 to bore the one cylinder I didn't think that was to bad? Am I right?
    Thanks Justin

    Punch it to 85.5mm and go wiseco setup.

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. Yamaha SUV 65U 1200 Motor question
    By BIGCAT in forum Yamaha PWC Performance (2-stroke)
    Replies: 2
    Last Post: 09-15-2016, 06:09 PM
  2. Polaris Virage i 800 to 1200 Motor Swap. Fuel Injected.
    By Harsax13 in forum Polaris Open Discussion
    Replies: 14
    Last Post: 08-16-2016, 10:10 AM
  3. '96 SL900 to 1200 conversion questions
    By bigred70 in forum Polaris Projects
    Replies: 35
    Last Post: 07-12-2010, 05:00 PM
  4. Carb Question 98 GP 1200
    By krispaintballz in forum Yamaha Old School Skis
    Replies: 5
    Last Post: 05-04-2008, 03:38 PM
  5. question on the 135hp 1200 motor.
    By Water4fire in forum Yamaha Open Discussion
    Replies: 19
    Last Post: 03-04-2007, 10:17 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
  •