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  1. #1

    HELP! What did I do WRONG

    Just finished up a completly rebuilt 1050 into 96 slx 780

    After about 45 min breaking the engine in, mostly mid throttle and after a while a couple wot quick runs. Right a way i noticed that it had a hesitation at low r's but wasn't worried yet. After the wot runs the engine would kill. Trying to figure out why I ran it again, and after the third I believe now that it seized for a short time..

    Apparently I took out 2 of the three pistons.

    Mag completely to where it closed the gap on the plug from the top ring seperating. Mostly on exhaust side. It was a Black and extremly dry looking plug. - Looks to be lean

    Center from basically seizing, even though the top looked to be washing out from over fuel. Black centers and clean outsides. - This boggles me

    Now about the engine. I bought it was a bad mag cylinder and had it bored .5mm over and a wsm piston. The other two I just replaced with also wsm .50 pistions leaving .009 piston to cylinder wall gap. Now I know this is high but thought I'd go this way instead of tight. Also replaced was the crank. I rebuilt all of the carb, with rebuild kits. The only thing at the time that I had found was that the mag accelerator pump sprayer was clogged. So obviously I cleaned it. Oh yeah and it was a salt water machine.

    Could it be a cooling issue. I did install a new stat and thought that I had all the hoses connected right. I even verified with the service manual. And as far as the MFD it works but its screen in funky. And yes I was running old gas, and possibly a dirty or clogged pre fuel filter. stupid me...

    Now I could understand that the mag has every sign of being lean but why would a washed out cylinder seize?


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by problown89gt View Post
    ...After about 45 min breaking the engine in, mostly mid throttle and after a while a couple wot quick runs...
    That isn't the commonly recommended break-in process.

    Break-in takes a lot longer than 45 minutes before you get anywhere near WOT, and you want several complete heat-cool down cycles.

    Old gasoline loses octane, so you could have detonation at mid-high throttle levels.

    Did you touch the engine to check for heat while you were running it? At normal heat levels you can touch the engine for several seconds without burning yourself.

    One important thing about these high power 2-strokes is that you can not safely run them with a possible fuel problem. If there is a problem, don't push the engine until you figure out what the problem is.

  3. #3
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    What were the rings gapped at?

    Were you using the thermostat?

  4. #4
    The fuel issue is very understandable and I will for sure take care of that. New fuel and new filters.

    There is one other thing that I forget to mention, What would cause the muffler to fill with water. When taking the exhaust apart the main exhaust pipe had some water in it and the muffler I would say was half or maybe a little less full of water.

    I am running a stant, which is brand new, and as far as ring gap, um I don't remember exactly but it was on the outer limit of the recommended amount. I want to say like .021

  5. #5
    rlharrison60's Avatar
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    Muffler? Isnt that called a WATER BOX? Or am I missing something?

  6. #6
    Quote Originally Posted by rlharrison60 View Post
    Muffler? Isnt that called a WATER BOX? Or am I missing something?
    So you are telling me it should have water in it?? I guess I really don't understand? Why and where would it becoming from?

  7. #7
    Lake Mead Bum & BTLS Mark starflight's Avatar
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    Water is injected into the exhaust to keep it cool, as well as muffling the sound. Cooling the exhaust keeps the hoses from melting.

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