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  1. #1
    jeffg426690's Avatar
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    XL 1200 Mystery Meltdown & Rebuild

    Ok guys, need some input and help!
    Ski- 99 xl1200
    Carbs - stock
    Stock motor w D-plate
    Ski was running good for the day, rough chop, hitting a few waves. Shut down at just over 3/4 throttle. Started again but slow turn over. Limped in to shore, checked plugs (good), ran but would not stay idling and was rough. Got ski to ramp just above idle.

    Compression check: #2 no compression, 1&3 about 110
    Pulled motor (not fun on the xl!)
    Head looks perfect.
    Pulled #2 and it had a light meltdown
    PV's intact, nothing broken there.
    No signs of anything else broken or amiss other than piston and light bits of alum from piston on cylinder.

    Thinking maybe air leak somewhere around carb 2? What else???

    Current plan: clean cylinders w muriatic and evaluate from there. Think it's able to be saved - input?
    New piston on 2, 1&3 were done by a shop less than 1yr (WSM pistons) - #2 was/is OEM
    Unknown hrs on motor (was swapped in by shop he bought it from, 1&3 replaced at that time)
    Thinking the best plan is too split the cases and inspect/ clean crank along w dealing w cyl/piston.
    Is there a way to clean things up without pulling crank out? That may be a dumb question but I don't know cause I've never pulled a crank out before (haven't had too yet...)
    Completely welcome to any thoughts and input! Some guidance w the crank would help a lot.Click image for larger version. 

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  2. #2
    butterbean_29512's Avatar
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    Jeff.....sorry that happened buddy! It doesn't look too bad..the cylinder may clean up with muriatic acid. The piston top looks lean. I'd check that carburetor for that cylinder. As for splitting the cases, I always split the cases, stone them, and clean and reseal them, using new seals.

  3. #3
    jeffg426690's Avatar
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    Quick question, the motor in this is apparently from an 01 or higher as it has the insulator / spacer between carb manifold and reed plate.

    Is this insulator/ spacer necessary? Can we go without and save on just having to use one gasket instead of two?

    This would entail using a stack of washers on long carb bolts to make up the difference and getting new short ones for the 4 that sit between the carbs (the PITA ones...)
    Is there a performance difference w the insulator?

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  4. #4
    jeffg426690's Avatar
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    Quote Originally Posted by butterbean_29512 View Post
    Jeff.....sorry that happened buddy! It doesn't look too bad..the cylinder may clean up with muriatic acid. The piston top looks lean. I'd check that carburetor for that cylinder. As for splitting the cases, I always split the cases, stone them, and clean and reseal them, using new seals.
    Thanks Jack!
    This is my buds ski, I was with him when it happened. Could also be the famous mid-lean seize since he's got stock jetting?
    All the pistons look lean w no sign of wash on them, hopefully he'll listen and we'll re-jet to the recipe - plan on doing the carbs one way or another.
    Can I pm you for details on cleaning up the crank and cases?

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  5. #5
    mudslanger's Avatar
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    Just wandering how long has it been since it was built.

  6. #6
    jeffg426690's Avatar
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    It has been since the beginning of the year that the ski was bought from a local shop who scavenged the motor from another ski and replaced piston 1&3 (WSM) and 'went through' the ski (no telling what that means).
    We'll have cylinders back tomorrow and hopefully can still use them.
    Another piston is on order along w base,head,pv, intake,exhaust gaskets and new seals for the crank.
    Will most likely be doing the carbs too w a re-jet.
    Any tricks or methods to cleaning the crank and cases?

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  7. #7
    Myself's Avatar
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    What do the head domes look like?

  8. #8
    jeffg426690's Avatar
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    Head domes are perfect, unmarred

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  9. #9
    Myself's Avatar
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    Are they also very clean like the piston top?

  10. #10
    mudslanger's Avatar
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    The reason I was asking about the rebuild is that the piston looks like a 4 corner seizure. The result of a piston not broke in properly and swelling up in the cylinder. Another symptom of what your piston looks like is that it is a little lean and someone run it for a long distance at wide open throttle. Lean enough to create heat at wide open throttle but not too lean. They run great at these carb settings but eventually melt down the piston.

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