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  1. #1

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    Sl 650 std backfire

    I have a 95 sl650std and when I got it, it had the intermittent spark got a new cdi box and boom fired right up. the other day I took it to the water just to start and let run. No riding. The ski did perfect. But once I got home and tried to start it again it started backfiring and wouldn’t start. Checked the cdi box all over and found out it was wrong cdi. Got another cdi correct part number and it’s still backfiring. It try’s to start sometimes but just ends up in a loud back fire. And thoughts on what happen from taking it to the water and letting it run on the trailer to why it might have started backfiring. And yes it ran with the wrong cdi box for probably 5 min total run time until I got the correct One

  2. #2
    Click avatar for tech links/info K447's Avatar
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    What are the part numbers for the ‘wrong’ and ‘correct’ CDI ?

    Post some clear photos of the insides of the electrical box.

    Any signs of corrosion or damaged wires inside the electrical box?

    Has the magneto stator been changed?

    Any signs of water inside the flywheel housing?

  3. #3
    Click avatar for tech links/info K447's Avatar
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    Click this link for lots of useful Polaris PWC info
    http://polarispwcknowledge.shorturl....t-things-to-do

    You may want to remove the spark plug caps, trim the plug wires back maybe 1/2” and then re-screw the plug caps onto the wire ends.

    What spark plugs are installed? Are they fresh/new spark plugs?

  4. #4

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    I just put brand new plugs in. Bpr8es ngk. New plug wires. No new stator yet. The other cdi box is for a 92. This one is for a 93 but I seen we’re a guy put a 93 on a 95 cuz the timing points are the same but not for the 92 year cdi. Just weird that it started with the other cdi ran for maybe 5 min of total run time then just started backfiring for no reason.

  5. #5
    Ryan Beernutz's Avatar
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    Quote Originally Posted by Matt387x View Post
    I just put brand new plugs in. Bpr8es ngk. New plug wires. No new stator yet. The other cdi box is for a 92. This one is for a 93 but I seen we’re a guy put a 93 on a 95 cuz the timing points are the same but not for the 92 year cdi. Just weird that it started with the other cdi ran for maybe 5 min of total run time then just started backfiring for no reason.
    If I remember correctly, 92-93 650s used an analog ignition system. If your ski is a 1995, you would need a CDI for a 94-96 Fuji (650, 750, or 780)

    Refer to this thread.


  6. #6
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Welcome to the Hulk.

    It's odd that it ran well and then developed the back fire problem.

    When it backfires through the exhaust, that means the exhaust port is open when a spark is introduced. (Bad timing)

    1. Check your crank phase to make sure it's not out of true.

    2. Check your ignition timing. It's controlled by the magneto position.

    3. Timing that is "off" may be due to a sheared woodruff key on the crank.

    If this is a new to you ski, did the previous owner tell you about any problems it may have had, and that's why they were selling it?

    People don't usually sell skis because they run good. They sell them because they are tired of sinking $$ into it.

    And if you're serious about replacing the magneto, I have a brand 650 factory magneto available.

  7. #7
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Quote Originally Posted by Beernutz View Post
    If I remember correctly, 92-93 650s used an analog ignition system. If your ski is a 1995, you would need a CDI for a 94-96 Fuji (650, 750, or 780)

    Refer to this thread.
    I'm pretty sure all 650's have analog ignition. And so did the 1993 SL 750. 1994 and newer all 750 and 780 were digital.

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