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  1. #1

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    Spark Plug Indexing

    TODAYS READ!!! sorry to those, no pics

    http://asog.net/content/view/19/25/

    very interesting bros


  2. #2

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    any body tryed this before! (ie) any inprovement , are piston washers avilable

  3. #3
    Click avatar for tech links/info, donation request K447's Avatar
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    Spark plug indexing can help a little bit. The engine must be in good operating condition beforehand, of course.

    How much difference the indexing makes depends on the engine and cylinder head design. Others have reported a 40RPM gain by indexing the spark plug gap to face the exhaust port.

    You can find spark plug indexing washers at many automotive supply shops, especially those that cater to the performance tuning crowd.

  4. #4

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    very informative k447 cheers

  5. #5
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Watcon.com sells the indexing washers.

    They are supposed to gain a little more RPM on the top like he described ^^^^.

  6. #6

  7. #7

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    Give it a shot, I kid you not it was worth over 100 rpm on one of my Sea Doo 951's. I also J cut the ground tang (place a razor blade in the gap to protect the electrode and file the ground tang back till you can look down and see half of the electrode) Had to add 1/2 the thickness of the seal washer to get the proper lineup to the exhaust port.

    I thought it would be a total waste of time but was pleasantly surprised.

  8. #8
    johnsonmtz's Avatar
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    Many years ago when Johnson/Evinrude (now Bombardier) first came out with FICHT outboards, they had a lot of problems with them. One of the first TSB's the engineers issued was to index the plugs so that the plug electrode was exactly (or nearly) opposite the injector. This was intended to cause a more complete burn and more even combustion throughout the entire dome.

    K447, have you ever tried anything like this on your FICHT injected Virage? I'd be curious to know if this would apply to the FICHT implementation used on that engine.

    So what direction is the plug suppose to face on a carbureted 2-stroke?

    KJ

  9. #9
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by johnsonmtz View Post
    Many years ago when Johnson/Evinrude (now Bombardier) first came out with FICHT outboards, they had a lot of problems with them.

    One of the first TSB's the engineers issued was to index the plugs so that the plug electrode was exactly (or nearly) opposite the injector. This was intended to cause a more complete burn and more even combustion throughout the entire dome.

    ...ever tried anything like this on your FICHT injected Virage? I'd be curious to know if this would apply to the FICHT implementation used on that engine.

    So what direction is the plug suppose to face on a carbureted 2-stroke?...
    I did try it on one of the engines, while chasing a rough running condition in the mid-range. Turned out to be an EMM problem

    Indexing the plugs might have made a small difference, but I have now sold that machine (with a good EMM installed, and the index washers still in place).

    I suppose at some point I will index the plugs on another of my Ficht machines.

    The tricky part is that the RPM gains from plug indexing can be small, and small changes in atmospheric pressure or air temp can also alter RPM by similar amounts. Even sitting differently on the seat, or a change in wind or wave conditions can affect RPM readings.

    A properly running Polaris Ficht engine should start, idle, and run properly without any indexing of the spark plugs.

    It is true that the early Ficht OMC outboards had some problems. Eventually they got it sorted out, but the company still went under. That is why the Polaris Ficht injectors now say BRP on them

    On a carb'ed 2-stroke, the plug gap is supposed to face the exhaust port, as I recall.

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