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  1. #1

    Such a silly question but I have to ask - what is on the inside of my ski?

    Take a look at the picture. I think what I have identified is right. But what about where I have the questions? I asked some folks who are familiar with the engine world and they got all confused too! At least I dont feel totally dumb. Anyhow...what is the anatomy of what I am looking at here?

    Thanks!
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  2. #2
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    Those are the fuel injectors. They inject fuel directly into the cylinders. The so called fuel lines are the oil injection.

  3. #3
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by sergv View Post
    Take a look at the picture. I think what I have identified is right. But what about where I have the questions? I asked some folks who are familiar with the engine world and they got all confused too! At least I dont feel totally dumb. Anyhow...what is the anatomy of what I am looking at here?

    Thanks!
    Many traditional automotive guys have never seen a direct fuel injection engine, which is why a Ficht engine seems so strange

    See my signature links for lots of useful info and even descriptions of how the Ficht engines work.

    I note that your engine has the original gray Tempo fuel hoses, which I expect are not getting stiff from age. More importantly, the fuel hoses are rubbing on the brackets for the fuel injectors. Polaris issued a service bulletin to inspect the hoses for damage from the brackets and then add protective plastic sleeving over the hose sections.

    Since the sleeving is not present on your engine it suggests that this engine was not dealer serviced. And that means other things may also not have been done or maintained.

  4. #4
    Thanks. So what is the box at the bottom of the picture and why is there oil going to it?

  5. #5
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by sergv View Post
    Thanks. So what is the box at the bottom of the picture and why is there oil going to it?
    A 2-stroke engine consumes fuel, air and oil.

    The fuel arrives inside the combustion chamber via the fuel injectors on top of the cylinder heads.

    The air enters the engine via the three large throttle body openings visible in your photo along the lower area, with throttle control via the three round flat valves you can see inside the throats. When you squeeze the throttle lever these three valves rotate to allow more air into the engine.

    On top of the throttle bodies is the flame arrestor, which many confuse with an air filter. When riding around out on the water there is very little dust, so no worries about the engine sucking in much dirt.

    However, the interior of the hull is an enclosed space when the seat is in place. The entire engine, all fuel hoses and the fuel tank are all in there together. If something were to leak fuel into the hull (which normally should never happen) there could be an accumulation of dangerous gasoline fumes. Even so, it will not explode or burn without a source of ignition such as spark or a flame.

    Sometimes a badly behaving engine will backfire. This does not happen often and usually means there is something wrong with the engine or the ignition system. If the engine was to backfire and flames did somehow come up through the throttle bodies, the fine wire mesh of the flame arrestor will absorb enough of the heat that the actual flames will not get past the flame arrestor mesh. So even if the hull happened to be full of gasoline fumes at that moment (which it should not) the hull still should not explode.

    Normally the flame arrestor just allows air flow into the engine and the cover provides modest shelter from water splashes should there be some water inside the hull.

    Unlike a typical car or truck engine, a 2-stroke engine does not have a reservoir of liquid oil inside. Instead the engine has a thin film of oil coating the inside surfaces. As the engine runs the air flow into and through the engine draws some of this oil into the combustion chamber where it is burned and exits the engine with the rest of the exhaust.

    To replace the oil that is lost as the engine runs there is a drip feed of oil added to the incoming air flow. These are the thin hoses you see connected under each throttle body air intake. There is an oil pump at the front of the engine. This pump is variable rate, it flows more oil as you squeeze the throttle and the engine revs higher and feeds oil more slowly when the engine is running less vigorously.

    There is an oil tank beside the gasoline tank. It is important to keep this oil tank well above empty. Most of us top up the oil tank after every two to three tanks of gasoline, more often if we remember to check it. The oil is special 2-stroke oil, very different from the oil used in a car or truck.

  6. #6
    So I also believe there is a carburetor...where is it?

  7. #7
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by sergv View Post
    So I also believe there is a carburetor...where is it?
    There are no carburetors on a Ficht fuel injected engine.

    Indeed, that is the whole point of having direct fuel injection - all the hassles and limitations of carburetors are displaced.

    On your engine what looks like the core of three carburetors are the throttle bodies. These are simply used as air valves to control how rapidly air is allowed into the engine. Squeeze the throttle lever while the engine is off to see the valves open.

    The majority of your mechanically inclined friends who know their way around cars and old-school carburetor engines will find themselves surprised by how your Ficht engine actually works. These engines were quite advanced for their time. Direct fuel injection is still quite unusual even today despite being used by Porsche and others.

    Polaris Ficht Fuel Injected Engines

    This video is for the outboard motor version of Ficht, so the fuel pump details are quite different on the Polaris PWC.

    Last edited by K447; 09-07-2014 at 09:48 AM.

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