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  • Re: Fun questions to stimulate and educate for the 912

    by » 11 years ago


    Hi Bill,

    Good job.
    Bill the answer to #14 is in the parts manual.

    Where is everyone else. These are question that may help you maintain and understand your 912 engine. Everyone that works on a Rotax 912 or owns one should have the manuals and the answers are all there.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell


  • Re: Fun questions to stimulate and educate for the 912

    by » 11 years ago


    Roger found the answer to #14; they are the same part no.
    14. What do the oil temp and cylinder head temp senders have in common? correct, they are the same part and interchangeable



    Have a question however. My engine instrumentation is a Grand Rapids EIS which came with a ring type cyl. head temp sensor like the ones that go under spark plugs only smaller. I questioned them about this and their instructions were to mount the ring type sensor under the existing sensor. This seemed like a waste to use two sensors in the same hole. I removed the existing sensor and installed the ring type with a brass bolt and heat sink paste. I then used the original sensor as a coolant temp sensor. I checked both with a remote thermometer at operating temps and they are right on the number. Do you foresee any problems with this setup?

    Bill.

  • Re: Fun questions to stimulate and educate for the 912

    by » 11 years ago


    Here are all the questions and their answers. I thought more people would jump on this and get them all right.


    What is the firing order for the Rotax 912? 1,4,2,3

    What is the oil content of a 912 engine? 3 liters or .793 US gal.

    What type of oil sump is used on the 912? Dry sump
    What is the integrated alternator output? 12V 20A DC
    What do the crankshaft drive gear and the dog gear have in common? Same 6 digit serial number
    What is the 5th trigger coil pickup used for? Tach signal
    How is the oil returned from the crankcase to the oil tank? Crankcase pressure
    How are the cylinder heads on the Rotax 912 cooled? Liquid cooling
    What is the cubic inch displacement of the Rotax 912? 82.5 cu/in
    What is the accepted gearbox friction torque, upper and lower limit? 30nm–60nm or 264in/lbs–531in/lbs
    What is the gear reduction ratio for the 912S series? 2.43:1
    What does the cylinder head temperature sender measure? The metal temp
    Where on the engine is the manifold pressure taken? On the carb balance tube
    What do the oil temp and cylinder head temp senders have in common? They are the same part and #
    On the carb, lifting the jet needle from the second to the third notch will do what? Enrichen the mixture
    What type of Loctite is recommended for sealing the gearbox surfaces? Loctite 5910
    If you do not have a tight seal on the top of the carb what will result? A lean mixture and hot temps
    What is the start up timing for the Rotax 912? 4 degrees before TDC (not on the new soft start module)
    What is the torque for the 912 spark plugs? 177 in/lbs
    What are the new spark plug gap settings? .023 - .027 in. or 0.6-0.7mm
    How many double ignition coils are necessary to normally operate the 912 engine? 4
    What does CDI ignition stand for? Capacitive discharge ignition
    How many charging coils are used on the Rotax engine ignition system? 2
    How often should the coolant be replaced? Every 2 years

    Extra credit:
    Through where does the vacuum in the venturi activate the carb piston and diaphragm assembly? 2 holes in the carb piston
    What will occur if the crankcase locking pin is removed and the bolt is not installed in its place on the crankcase and the engine is started? Oil will not returned to the external oil reservoir
    What type of coating is on the 912 cylinder walls? Gilnisil
    Why are you not allowed to rework the valve surface on the Rotax 912? The valves are armor-plated
    How is the correct pressure established in the carb float bowl and by what method? The bowls are connected via a tube that connects to the airbox and the carbs then operate under the same pressure

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell


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