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  1. #1

    Diagnose cause of melted PTO piston SL 750

    I have been doing a lot of reading, and it appears the SL 750s are notorious for fuel system problems leading to lean condition damage.
    I have looked at some causes here:

    It seems it's probably not a fuel delivery problem, since it only happened to the PTO, and that one "gets fuel first" from the single output fuel pump.

    I'm guessing maybe an air leak or dirty carb? Is it possible to narrow down visually (melted edge vs. hole in center)?

    Any help would be appreciated. Otherwise, I may (naively) just clean and rebuild the carbs.

    Thanks for the help.
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  2. #2
    BlueFishCrisis's Avatar
    Join Date
    Aug 2011
    Medina, Ohio, United States
    Welcome to the Hulk! While it is true the PTO carb gets fuel first, the nature of the fuel rail allows fuel to flow directly past the first carb as well. A dirty carb or stuck needle/seat would force the fuel past to the other two. If it hasn't been done recently, a carb REBUILD with new needle and seats is in order, and will run around $165, if you do the labor yourself. This may have also been caused by incorrect needle valve settings on the carbs. These should be reset to factory when you do the rebuild. To prevent future burn down, and for a better sense of security, the fuel pump should be upgraded to the trippple outlet for around $50 complete, again if you do the labor your self. Also, all of the fuel lines should be replaced, and you should ensure the return restrictor is in place in the return line. The fuel tank should be opened up and inspected, with the lines internally replaced as well, if you do not have the one piece sender. Lastly, the shut off valve should be cleaned inspected and possibly replaced if it leaks. Any air in the system will cause a lean condition.

    See more info here: Http://

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