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  1. #1

    Join Date
    May 2019

    Angry Polaris SLT 750 Engine Siezed on Last Ride of the Season

    Hello All,

    So of course on the last ride of the season I put Stabil in the gas and am riding at near full throttle and all the sudden the engine locks up try to bump the starter and doesn't budge. I get back to shore and I pour 2-stroke in the cylinders and gave it 5 minuets and after two bumps of the starter if freed up the engine.

    Because of the type of person I am I will not be able to sit all winter without knowing why this happened and I was looking for input. I run premix 40:1 and just filled up the tank before this ride so I know that there was adequate oil but I believe I put 4 oz of Stabil in the tank when I should have put 3. Is this Enough to throw off the premix mixture?

    Would this for sure be a top-end issue because the fact that putting oil in the top-end freed it up almost right away?

    Any input would help,

    Thank You,

    Jake B.

  2. #2
    Click avatar for tech links/info K447's Avatar
    Join Date
    Jul 2007
    near Toronto, Canada
    What year is your SLT 750?

    How many running hours since the last engine or top end rebuild?

    How many hours since the last jet pump rebuild?

    What was the water temperature on that last WOT ride?

    Is the stock thermostat and bypass valve present inside the thermostat housing?

    If the engine top end has been rebuilt, what was the piston clearance and ring end gap set to?

    It is possible the jet pump bearings have seized. The failure symptoms can be similar to what you described. Remove the jet pump and inspect for possible bearing damage.

    I doubt the Sta-Bil dosing had anything at all to do with the engine stopping while riding.

    If the engine will start (jet pump and driveshaft removed), run it without cooling water for about 15 seconds. This should burn off much of the oil you added.

    Then check cylinder compression.
    All spark plugs out, throttle held wide open.
    Battery healthy and well charged.
    Look for a cylinder with markedly less compression or slower to build compression.

  3. #3

    Join Date
    May 2019
    Thank you for the response K447,

    - It is a 1995 SLT 750

    - It has had 120 hours on this top end. It was 3 years ago that I rebuilt the entire top end all 3 jugs and pistons. I also have a triple outlet fuel pump in it.

    -I rebuilt the jetpump only about 3 hours ago as I was getting cavitation before.

    - The water temperature was about 58 degrees.

    - Yes I have the stock thermostat in the housing

    - I believe the ring gap was .5mm

  4. #4
    Click avatar for tech links/info K447's Avatar
    Join Date
    Jul 2007
    near Toronto, Canada
    Quote Originally Posted by Jacob03 View Post

    - It is a 1995 SLT 750

    -I rebuilt the jetpump only about 3 hours ago
    It is possible the jet pump rebuild did not work out.

    It is straightforward to remove the jet pump and check for potential problems.

  5. #5
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
    Join Date
    Oct 2006
    Cleveland OH
    Did you properly warm the engine up prior to WOT?

    Cold water and improperly warming the engine up can lead to cold seizure. Usually happens with forged pistons, not cast. Prob why K447 was asking about ring gap.

    Generally this time of year the water is colder, the air is colder, and the carbs would need to be adjusted most likely because of that. This normally would lead to a holed piston as opposed to a seizure though.

    Pop the heads off and lets have a look see at what you got.

  6. #6
    sdlvx's Avatar
    Join Date
    Aug 2007
    If you are running quality oil you can run better than 50:1. But because the carbs are providing the oil to lubricate your engine, if something goes wrong with your carbs you don't get enough oil. 40:1 is very safe ratio and you could run 50:1 with good oil. But I wouldn't recommend it because it's more likely to have problems.

    With oil injection, even if the engine is getting no fuel the oil pump will pump oil into into engine as long as there is some in the oil tank. My vote is in cold seize, this time of year you have to be careful, you are dumping 58 degree water on a metal engine running at 135 degrees. Lots of stuff expanding at different rates.

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