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  1. #1
    c.res.q's Avatar
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    New guy here needin some help

    Hello everyone. My name is Chris and I recently purchased a '95 Polaris SLT750. It was not running when I bought it so I started with the carbs. Took them apart, cleaned, and put back together. Ski started up and runs great except one cylinder is running hot. The magneto cylinder is running hotter than the center and PTO cylinders. I have replaced all fuel lines, rebuilt the carbs and fuel pump, replaced the fuel selector switch, pulled the water rail and checked to make sure I have good water flow, and I took the oil system out and went pre-mixed. The other 2 cylinders are as cold as the water is so that kinda excludes all the things they have in common, i.e. fuel/oil mix, cooling water. I thought of it running lean but we made adjustments to the carb with no success. Any help would be greatly appreciated. I have been doing research on this site and you guys have a top notch deal going here. Very informative and friendly conversations.PLEASE


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Welcome to the Hulk!

    How much hotter is the MAG cylinder/head?
    Too hot to hold your hand on it?

    Have you run it in the water, or just on the hose?
    Where did you connect the hose, if that is what you are using?

    How did you confirm that you have good cooling water flow through the front cylinder?

    What do the spark plugs look like?

    I presume you have already found the Polaris Service Manuals?

  3. #3
    OLDJETSKIMAN's Avatar
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    Hello Chris, welcome to the form. These guys are great on here. I have the same ski 95 slt750 One the frist things the experts on here will tell you is to up grade to a triple fuel pump this gets fuel evenly to each carb. The o.e. pump is the reason for many of these skis burning a hole in one piston. Lean cond. But I am sure the pros will respond soon to your problem. Welcome again.

  4. #4
    seaobin's Avatar
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    Im with K447 Mag Cylinder will run hotter on the hose if the hose is connected to the water rail.

    Pull the plug and tell us how it looks.
    get a small flash light and look through the spark hole and see if you can see the piston . What does it look like?

    Definitely upgrade to triple fuel pump, or you will be chasing your tail trying to adjust the carbs

  5. #5
    c.res.q's Avatar
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    The mag cylinder will warm up as the engine idles, but as I increase the rpm's it will get too hot to hold my hand on. I have only run it on a hose at the flush kit for fear of blowing that cylinder. The spark plugs are fine. They all look the same, no difference between the 3. I pulled the water rail and blew air into each orifice. The magneto cylinder sounded like it had minor blockage but after 2-3 times it sounded the same as the other 2. When I pulled the rail the first time I found RTV in the thermostat area so I figured a blockage on the exhaust side. It appears as though thats not it. Reading the manual it says to do a crank index, but at this point it doesn't make sense because the other 2 cylinders are not hot. My thinking is if 1 is out of sync, the other 2 would also be out. 120/120/120. Thats were I'm stuck. It has reed valves, could the exhaust be stuck closed? Is it the nature of these engines to have the furthest cylinder run hotter than the closer 2?????

  6. #6
    seaobin's Avatar
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    Take it to the lake and leave it strapped to teh trailer. You do not wan tto run the ski for more than a few minutes on the hose. (will destroy your pump bearings) Let it idel and see if the cooling is better in the water. The reason that gets hotter is that it is the farthest from teh flush point, but closest to the intake side. So it will be cooler in the water. (or you can insert a T in the main line from pump to exhaust manifold and do your cooling from there. Just remember to clamp the cooling line behind the T (toward the pump) so that the water goes through the engine and not just out the pump

  7. #7
    c.res.q's Avatar
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    Seaobin, I will give that a try for sure. I looked at the book again and realized that the flush kit is actually on the outlet side of the water railI will let ya'll know how it does with that after this weekend. Ski is at my in-laws 45 minutes from my place. Thanks a bunch for the help and keep it coming, please....

  8. #8
    OLDJETSKIMAN's Avatar
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    Chris, when I joined, I had two skis and they called it a starter kit. Get ready your gonna be hooked You will be wanting a pro next. HOWDY YALL!!! Love Texas been there four times for training. Good luck with SLT, Go to you tube check out beerdarts 750 with the pro engine search pro 785!

  9. #9
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Welcome to the Hulk Chris.

    When being ran on the flush kits, the MAG usually gets hotter than the other 2 for 2 reasons.
    1. it's the farthest from the water source, so it gets the least.
    2. The Magneto is in front of it, and it generates heat as well.

    What I suggest is disconnecting the 3/4" hose from the jet pump on the inside of the ski. (next to battery). Connect the garden hose to that inlet and run it. That will replicate the same coolant flow like being on the water. See how the temp of the MAG cyl is then.

    NOTE: THE ENGINE MUST BE STARTED BEFORE THE WATER IS TURNED ON. THEN THE WATER MUST BE SHUT OFF BEFORE THE ENGINE. This is to prevent possible filling of the engine with water.

  10. #10
    johnsonmtz's Avatar
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    Quote Originally Posted by c.res.q View Post
    ......I recently purchased a '95 Polaris SLT750. It was not running when I bought it so I started with the carbs. Took them apart, cleaned, and put back together.....The magneto cylinder is running hotter than the center and PTO cylinders. I have replaced all fuel lines, rebuilt the carbs and fuel pump, replaced the fuel selector switch, pulled the water rail and checked to make sure I have good water flow, and I took the oil system out and went pre-mixed.
    Very good info so far regarding running the ski on the lake. Also note that you need to have the ski setting level in the water while you run it on the trailer. I did a top end job on my ski this summer and took it to the lake for a fast idle break-in. I left it on the trailer but only had the intake area of the ski in the water. I noticed the MAG was warmer than the other two and then backed the trailer in further so the ski set level. That evened out the water flow to each cylinder and the temps were about the same on all 3 after that.

    You said you rebuilt the fuel pump. Is than an original single outlet pump? If it's a single, you may be running the MAG lean and that's the reason for the higher temp. If that's the case, I'd strongly suggest you switch over to a triple outlet pump and avoid leaning out a cylinder.

    KJ

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