550/650 troubleshooting, need help!
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  1. #1
    PWCToday Newbie MitchInMN's Avatar
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    May 2017
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    Prior Lake, MN
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    50

    550/650 troubleshooting, need help!

    Hi guys, I have a 550 hull that I swapped a 650 motor into last winter. Just a little background on the ski to hopefully narrow down my issue a little bit easier:
    almost all stock 650 motor
    new crank seals last winter with about 25 hours run time on them now
    stock carb with stock air filter
    stock 650sx pipe
    rebuilt and tuned carb
    oil blockoff
    crankcase blockoff
    all new gaskets last winter
    all 650 electronics in a 650 ebox
    even 150/150 compression
    always used dominator oil and 93 octane
    no carb settings were changed Between when it ran and didnít run

    so onto my issues:

    finished the ski last last spring and got it running and tuned very easily. It ran great for a weekend on my local lake, absolutely no issues.
    Brought it to a cabin up north and ran it all day for 5 days straight and the thing didnít skip a beat, I was so pleased with it. Took it out of the water each night So it wouldnít sit and fill with water.
    Brought it home after the 5 day run and ran the water out of it in the driveway to make sure it was fully flushed. The next weekend took it out again on my local lake with no issues.
    Then I brought it to a different cabin, started it on the trailer before launching. Got it on the water and about halfway across the lake it quit on me. Put it up on the swim deck of a ski boat and got it back to the cabin. Wouldnít start the rest of the day and we were out ripping on other skis so I wasnít too worried about it. The next morning it started right up so I let it sit and idle in the water. Eventually it quit out. Started right back up again, and ran about 2/3 as long as the first time. Started a third time and it ran 1/3 of the amount of time. Once itís warm it wonít start back up. It seems like something electrical to me since all my fuel lines and check valves are new, along with crank seals last winter during the rebuild.

    Sorry for the long Long write up, just want to get this thing handled this winter so I can enjoy it next summer again.

    Any and all suggestions would be greatly appreciated!!
    1994 750sx
    1989 650sx
    1987 550/650 swap
    1984 js550

  2. #2
    I dream skis sportsfreak29's Avatar
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    Oct 2011
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    Midland, Tx.
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    754

    Re: 550/650 troubleshooting, need help!

    Install a primer in place of the choke, rebuild the fuel pump, replace the inline check valves on the fuel line and tank vent with a new ones, and replace all your fuel lines.

    It's possible that you are loosing prime somewhere or a tank vent check valve failure is creating vacuum in the tank, and it's not able to pull fuel to the carb.

    If the problem persists, then it could be a bad connection somewhere, or your stator, cdi or voltage regulator may be going out.
    Last edited by sportsfreak29; 10-10-2018 at 02:59 PM.
    If you're not crashing, then you're not trying!!!

    Ski situation in limbo!

    Special thanks to Chris Newmiller, and Mitchell at M&M Marine!

  3. #3
    PWCToday.com Is My Home Away From Home Rushford_Ripper's Avatar
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    Re: 550/650 troubleshooting, need help!

    Bad connection or bad stator coil?


  4. #4
    I dream skis sportsfreak29's Avatar
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    Re: 550/650 troubleshooting, need help!

    Agreed, but I'd do all the fuel system work anyways.

    It's a couple hours of work, and 50.00 worth of invaluable preventative maintenance.

    If you have air leaks in the fuel system or fuel delivery issues caused by a bad fuel pump, and the motor goes lean on a WOT run, you're going to roast your top end.

    I've been there, wasn't fun, and cost me some bucks to repair, not to mention the riding time lost.

    If it is the stator, I still have a couple available for purchase.
    Last edited by sportsfreak29; 10-10-2018 at 05:32 PM.
    If you're not crashing, then you're not trying!!!

    Ski situation in limbo!

    Special thanks to Chris Newmiller, and Mitchell at M&M Marine!

  5. #5
    PWCToday Newbie
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    Jun 2018
    Location
    WA
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    34

    Re: 550/650 troubleshooting, need help!

    CDKII has trouble with the gaskets/diaphragm between fuel pump & carb body, the partition gasket likes to sag between them, messing up pressure.
    Also measure the exciter coil resistance/continuity. & yes, my summer was a nightmare. : (

  6. #6
    PWCToday Newbie MitchInMN's Avatar
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    May 2017
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    Prior Lake, MN
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    Re: 550/650 troubleshooting, need help!

    Thanks for all the responses guys, I really appreciate it. Sportsfreak29, I have a primer kit for it that I ordered last winter but never saw the need to put it in so i'll do that this weekend. I usually do fuel lines and check valves every winter on all the skis so ill get to that at the same time. If that doesn't seem to help I will start testing electronics. pepper22, I have an SBN44 that I was planning on rebuilding at some point for this ski so that may be the next step since i'll have the time to get into it now that riding season is ending. 33 degrees when I got up this morning!
    1994 750sx
    1989 650sx
    1987 550/650 swap
    1984 js550

  7. #7
    I dream skis sportsfreak29's Avatar
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    Oct 2011
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    Midland, Tx.
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    Re: 550/650 troubleshooting, need help!

    You'll be amazed at the additional top end response the 44sbn will give you.

    I had one in a box for 10 years, and after finally installing it, I felt like a complete idiot for not doing it immediately.

    I ran a 2.3 n/s with 21psi pop of, 115/145 jets. Low at about 1 turn out, hi at 1-1/8. Ran perfect at sea level to about 3000 ft elevation, 185 psi compression, factory pipe 650 limited, and a skat 9/17. JS550 with a 650 motor and 650 pump swap. Pure power and speed!
    Last edited by sportsfreak29; 10-12-2018 at 02:46 PM.
    If you're not crashing, then you're not trying!!!

    Ski situation in limbo!

    Special thanks to Chris Newmiller, and Mitchell at M&M Marine!

  8. #8
    I dream skis sportsfreak29's Avatar
    Join Date
    Oct 2011
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    Midland, Tx.
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    Re: 550/650 troubleshooting, need help!

    Quick note: Explore the new top end power with care.... The old 28mm had nothing left after about 2/3 throttle, I pinned the throttle at about 45 mph, and the ski ripped it's self out from under me. The ski was a good 20-30 feet ahead of me when I hit the water, and it was one hell of a face plant!
    If you're not crashing, then you're not trying!!!

    Ski situation in limbo!

    Special thanks to Chris Newmiller, and Mitchell at M&M Marine!

  9. #9
    PWCToday Newbie MitchInMN's Avatar
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    May 2017
    Location
    Prior Lake, MN
    Posts
    50

    Re: 550/650 troubleshooting, need help!

    well I pretty much feel like an idiot at this point. Started the ski up and it acted the exact same way, run, die, run a little, die. I figured i'd just start at the tank check valve and go from there, pulled it off, the thing was absolutely locked up. vacuum in the tank. As I ran it more it kept building vacuum until it couldn't move any gas. Anybody have a suggestion as to where I should buy new check valves? Don't want this to keep randomly happening.

    Thank you sportsfreak29!! you saved me a lot of testing time that I was ready to just jump into.

    I've read about the SBNs a lot since I have one sitting around, and that's what I keep hearing over and over, do it sooner! I just kept the 28 on there for reliability and getting the ski on the water as fast as possible. since my reliability went out the window with this tank vacuum issue.... I guess now is the time haha. I also read all about the stock pipe mod so I think I may do that with my existing pipe before trying to find something aftermarket.
    1994 750sx
    1989 650sx
    1987 550/650 swap
    1984 js550

  10. #10
    I dream skis sportsfreak29's Avatar
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    Oct 2011
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    Midland, Tx.
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    Re: 550/650 troubleshooting, need help!

    Awesome, glad you found the problem.

    Try Parts Unlimited, Watcom, or Atlantic Jet sports. They should all have what you need. Probably 15.00 or less.
    Last edited by sportsfreak29; 10-13-2018 at 11:54 AM.
    If you're not crashing, then you're not trying!!!

    Ski situation in limbo!

    Special thanks to Chris Newmiller, and Mitchell at M&M Marine!

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