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  1. #1

    95 slx first lake run! Weird issue. Need advise.

    Ok I am typing this from my phone to pardon any errors. I took the new to me slx 780 out today after freshening her up. Everything was perfect for about three hours. I started off slow and worked up. The last hour I was running full throttle and everything was great until the last 20 minutes. It seemed to stumble once in a while after idling, and when cruising at around 4100 rpm I detected a little miss every now and then. I did one last high speed run and when I tried to go again it fell on it's face. I thought I holed a piston. I headed back to shore at idle and just before I got back I tried it again and she jumped up and went. Needless to say I did not hole a piston, but I think it got hot. When I got home I did another compression test and they are all between 135 and 140. The PTO was the lowest. Now before I took it out I had 150 across the board. Here are my questions.

    1 . Does a warm engine show lower compression or did I hurt it.
    2. I live in Texas and the water is really warm, should remove the t-stat? I verified it opens at 140
    3. I had about 3 gallons o 40:1 premix in the tank before I added more gas to rely on the oiler system. Is that a bad thing? Could that have loaded up the carbs.
    4. I added seafoam to the tank to clean out the system. Could this have caused the stumbling and missing after about a couple of hours? O
    I remember a boat of mine doing this as varnish made it's way through the carb. She was smooth as silk for about two hours.

    I really love how much power this ski has compared to my sl.


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    On these 2-stroke PWC SeaFoam and similar fuel additive products never seem to actually fix anything. They just make it seem like you are doing something. If it needs cleaning or fixing, SeaFoam probably won't do it.

    What did your 'freshening up' include?
    Carb rebuilds and internal cleaning?
    Replacing the fuel lines?

    Is your MFD display working?
    Any red lamp or warning messages?

    Did you check all electrical connections inside the electrical box?
    Remove and clean all engine ground connections?

    Do you have the correct NGK spark plugs installed?

  3. #3
    My mfd works great, and no red lights at all.

    Here is what I did.

    New bpr8es plugs
    New sending unit in the tanks ( it was missing)
    Cleaned the gas tank
    Verified the oil system is working
    Checked pop up pressure and was 21
    Engine is very clean with 24 hours on the clock

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by friscoboater View Post
    My mfd works great, and no red lights at all.

    Here is what I did.

    New bpr8es plugs
    New sending unit in the tanks ( it was missing)
    Cleaned the gas tank
    Verified the oil system is working
    Checked pop up pressure and was 21
    Engine is very clean with 24 hours on the clock
    Clean the carburetor internal filters?
    Replace the original gray Tempo fuel lines?

    Clean and test, or rebuild, the fuel selector valve?

  5. #5
    All the lines are black, no grey at all. I just got home after a friend BBQ and the compression is all back where is needs to be, between 145 and 150. Seems that being warm was the issue with the lower number on compression. Not sure why it would fall on its face after two hours of riding and not be hot.

    Should I remove the T-stat? I seem to remember when two strokes get hot they run like crap.Let them cool down and everything is good.

  6. #6
    bowsniper's Avatar
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    there is absolutely no reason you cant run that ski all day without it getting hot, i can run my slt all day in the 90's with no problems. they are watercooled engines just like a car is. just a different radiator! lol

    check the pick up screen and tube for debris, the inlet screen on the big pipe with the little fitting on it and the intake water hose all the way to the front of the pipe.

    you may just run like crap because of all the extra oil and seafoam. but I would lean towards some other issue,. maybe drain the tank and burn that in your lawnmower and start over. wont hurt the lawnmower.

    that will eliminate water in the fuel, bad gas, too much oil, additives and gives ya achance to suck up any junk in the tank.

    then check your fuel filters and the filters in the carb.

    drain the seperator and refill it with 2-stroke oil /gas mix again. maybe pop the diaphrams off and see if they have liquid where there shouldnt be..

    sounds like its missing liking it injested some water in the carb.. or its just dirty.. sometimes just replacing the diaphram restores it like new. they just get old in there after 15 years whether you use it or not.

    just a few ideas to try. did you check to see if your getting bright blue sparks from each plug? it should look like an electrical storm. not a sunset.lol

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