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  1. #1

    1999 XL 1200 Ltd. RPM question

    99 XLL <110 hours Stock except for dplate/chip, waveeater clips and couplers, pump seal kit (all just installed while carbs were out). Had stuck throttle shafts. Reamed busings per sticky and reinstalled carbs. No settings changed. Carbs were rebuilt within last year and running perfectly before binding. Adjusted throttle, choke and oil pump per factory manual. Use Yamalube 2W and premium (91 octane) Chevron fuel. Rode ski today. Throttles performed flawlessly. Runs smoothly throughout throttle range but cannot get RPM above 6500 on factory display. Indicates 54-57 mph on factory display but inconsistent. It seems before the mods and sticking shafts the rpms were higher. It is drinking fuel and oil at a massive rate. Approximately 3-4 hours on the water today and came to the dock on reserve and one bar down on oil. Pulled plugs when I got home and they are slightly oily, dark brown. Please advise. What is the factory redline/expected max RPM? Could this be carb adjustment or another problem? I did not adjust the powervalves after installing the clips and couplers. Could they be limiting ultimate rpm? Thank you all very much for your advice and assistance.

  2. #2

    Join Date
    Jan 2006
    Texas City, Texas
    Focus on your power valves first.

    They should show opened at 6500 rpms, but are they wide open? You may have to disconnet the power valves from the cables and rotate them to the full open position manually, then mark them in a way that you can see if they fully open while you are at top rpms with the seat off. Reconnect the cables, put the boat on a water hose, rev the engine slowly and see if they fully open.

  3. #3
    Powervalves adjusted per manual. Servo actuating through full range. Smoothly operating from closed to open.
    Checked compression; #1 120, #2 120, #3 105.
    Plugs are identical and show very slightly rich mixture.
    Any further thoughts (other than the low piston will bear watching)?

  4. #4

    Join Date
    Jan 2006
    Texas City, Texas
    Maybe your not asking the right questions. First off, the factory display is usually very far off. It would be hard for anyone to get a good picture of what is going on with your boat with that information. It would be better if you were to buy or borrow an aftermarket tachometer and GPS to get some hard data. With this data, you can then compare your stocker to other stockers out there. You may find that there really is no problem at all. On the other hand, knowing what the normal operating rpms for your model boat may tell you that you really are on to something.

    With an older unit like yours, you may find that your boat is average amoung stockers, and that you need an aftermarket impeller, to seal your pump shoe and to get a 5 degree thrust nozzle to really wake it up. This is a best case scenario.

    Here is your worst case scenario: a difference in 15psig could mean that you are in the process of loosing a piston/cylinder combo.

    If it were my boat, I'd pop the head and take a look at the piston. If it is bad, the only thing that will happen as you ride it is that it will go from bad to much worse. Much worse translates into more expensive to fix.

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