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  1. #1

    Unhappy 2003 XLT800 Engine Blown?

    Well, it looks like it did it (again).....I was out in the river and the machine just lost all power and wouldn't restart. I towed it in with my trusty 4 stroke and got it on the trailer.

    Once home, I went to the compression gage and it didn't look good...120psi on the front cylinder and 90psi on the back. I got it started and there was a loud knock that was present.

    Over the past year, I have had the carbs rebuilt, changed out the cylinders and pistons, removed the oil injection pump (all at once) and the machine has been running beautifully for almost a year. I probably have 25-30 hours on this engine.

    For the life of me, I can't even start to think about what could have happened here. The machine was running wonderfully and the world was grand. Just happened all of the sudden. I had been idling quite a bit today and the plugs were loading up a little, but a little run with WOT and the machine was running well again.

    I'm about at the end of my rope with this thing. Any idea what could have happened here? I don't know if I have another rebuild in me...



  2. #2
    mudslanger's Avatar
    Join Date
    Jul 2010
    Huntsville Al
    It may have dropped a power valve. what ever it is it will be worth it when its running again.

  3. #3
    silvercrxsir's Avatar
    Join Date
    Sep 2011
    How do the plugs look,did you get a lean condition

  4. #4
    I remember getting an upgrade kit for the power valves when I put the new pistons in. The plugs looked great (light brown). I'll have to checdk out the power valves. Thanks for the heads up, I'll let you know the outcome!

  5. #5
    Now I'm perplexed...I took the head off and the Pistons look fine. Power valves seem to be in place on both jugs. I can turn over the motor with no problem. Before I took off the head I started it again and there is still aloud clanking. I though maybe a rod journal on the crank, but why the drop in compression?

  6. #6
    did you damage a ring?

  7. #7
    I don't think so. The inside of the cylinders are very clean. Just not sure what could account for the loud clanking. These were brand new rings.

  8. #8
    If the rod to crank bearings are bad it will not push the piston far enough up to give it top compression. I had that issue and the rod will rub the bottom of the case. Hope that isn't the issue but my compression dropped from 120 to 90 when I had that issue.

  9. #9
    Yikes...How tuff was it to change the bearings? Was the Crank damaged?

  10. #10
    Crank would need to be replaced. You can pull the cylinder jug off and grab the rod/piston and push / pull on it to see if you have slop (excess play) at the bearing.

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