Page 1 of 5 1 2 3 ... LastLast
Results 1 to 10 of 47
  1. #1

    Yamaha 1200 xl ltd jetting problems

    I just rebuilt the engine in my ski. It had a melted piston probably due to dirty carbs and a bad carb check valve. I bought the ski with the bad engine. I rebuilt the carbs did the return balance and drilled the restrictions. 110 low jet 120 high jet pop of with 1.5 is 43 psi. Ran the ski for the first time and it ran good but was super rich below 4000 rpms. Today took off the exhaust and turned the t handles on the lows in a little at a time and started each time but even with them all the way bottomed out it runs so rich it will choke me out of the shop and the idle speed doesn't increase. Has a d plate installed and the rear exhaust resonator removed and replaced with a hose from a 98 model. Do I need to go down on the jet size?


  2. #2
    jeffg426690's Avatar
    Join Date
    Jul 2015
    Location
    Sarasota, FL
    Posts
    471
    +1
    42
    What's on the intake? Fa's? Stock intake? Modified stock?
    Choke plates still in?
    Accel pump removed?

    To tune the lows, you really need the ski in the water w a load on the motor and a tach other than the stock guessOmeter. You can do it on the trailer, backed on @ a ramp. That's according to Group K tech articles, everyone has their own twist.

  3. #3
    Yamaha artisan Cutlass's Avatar
    Join Date
    Oct 2010
    Location
    Madison, WI, USA
    Posts
    2,536
    +1
    62
    Agreed. Adjusting the carbs while the ski is out of the water accomplishes nothing. The engine has no load on it and acts very differently. You have to adjust it in water.

  4. #4
    Modified stock airbox with no silencer. Chokes still intact. The idle is about the same out of the water so I thought I could get the lows close. It's hard to believe that the idle jet needs to be so much bigger. The stock size is 87.5 and I have a 110 in now. Has anyone ever though of attaching some hard plastic tubing like for air brakes to the carbs to be a sleeve then making a screwdriver from a speedometer cable to insert and adjust? They could be fixed so that lows could be adjusted with exhaust on. And yes I did check the needle valve arm height during carb rebuild

  5. #5
    butterbean_29512's Avatar
    Join Date
    Sep 2013
    Location
    Bennettsville, SC
    Posts
    1,163
    +1
    103
    Its best to stick to the recipe. If you try to tune it too much you'll end up burning it up again. 2 strokes are supposed to smoke.

  6. #6
    jeffg426690's Avatar
    Join Date
    Jul 2015
    Location
    Sarasota, FL
    Posts
    471
    +1
    42
    How is the stock airbox modified? Just open w ducts removed ?

  7. #7
    The screen has been removed along with the intake silencer. At high speed the screen would be the most restrictive part. This wouldn't affect the low speed airflow though. It's not just smoking like normal it is putting out raw gas from the exhaust. Has anyone ever ran the European jetting and had any luck?

  8. #8
    jeffg426690's Avatar
    Join Date
    Jul 2015
    Location
    Sarasota, FL
    Posts
    471
    +1
    42
    The screen is the actual flame arrestor of the stock intake and needs to be on to protect against a backfire situation. The airbox cover itself should be swiss-cheesed w as many holes as you can put in it (I used a 1" spade bit).

    It sounds like your not getting enough air. The recipe is a tad rich on highs and lows w the turns as described in the sticky but not as much as you are describing. The recipe is tried and true but needs the appropriate airflow to work.

    You either have an airflow issue or fuel leaking issues inside the carbs. What's the pop-off set at? Did you pressure test the carbs while doing the pop-off? 1.5 N&S?

  9. #9
    Yes 1.5 n&s 45 psi pop off. If I had a fuel leaking problem I would think it wouldn't be all three carbs. The plugs are soaked if it idles for a min or two.

  10. #10
    jeffg426690's Avatar
    Join Date
    Jul 2015
    Location
    Sarasota, FL
    Posts
    471
    +1
    42
    Your airbox should look something like thisClick image for larger version. 

Name:	20160508_223350.jpg 
Views:	21 
Size:	49.6 KB 
ID:	439321

Page 1 of 5 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. Is it worth modifying my 1999 Yamaha 1200 xl ltd
    By canon714 in forum Yamaha PWC Performance (2-stroke)
    Replies: 2
    Last Post: 06-30-2015, 04:15 PM
  2. where to connect 2000 Yamaha 1200 xl ltd exhuast temp sensor
    By spray&Splash2011 in forum Yamaha How To & FAQs
    Replies: 8
    Last Post: 09-27-2014, 08:20 AM
  3. 1999 Yamaha 1200 Xl ltd shops want $2,600 to repair need advice and help
    By canon714 in forum Yamaha PWC Performance (2-stroke)
    Replies: 15
    Last Post: 09-19-2014, 03:51 PM
  4. yamaha 1200 xl limited problems
    By bbowen25 in forum Kawasaki PWC Performance (2-stroke)
    Replies: 1
    Last Post: 08-06-2013, 08:27 PM
  5. 2000 Yamaha 1200 XL Limited problems
    By Ryallen in forum Yamaha PWC Performance (2-stroke)
    Replies: 20
    Last Post: 05-09-2013, 11:25 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
  •