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Thread: re: install ignition coils Rotax 912uls

  1. #1

    Question re: install ignition coils Rotax 912uls

    I am installing a Rotax 912 uls 100hp engine into a Model IV. the Model IV Firewall Forward Instructions (dated Dec. 01) In section B. Engine Mount Installation
    Number 1. Instructs: Unbolt the ignition coils from the engine-these will be reinstalled later using different brackets. Nowhere do I find further instructions to re install the coils or any reference to "different brackets". Can anyone help me with this, and are there any updated instructions to install this engine to Model IV. John McBaen no help with this matter.

  2. #2
    Senior Member
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    Default Re: install ignition coils Rotax 912uls

    I'm sure the reason for removing the coils and modules is the intake manifolds get swapped from one side to the other. When I installed the 912 in my Kitfox 4, I made a bracket that mounted on the firewall side of the motor mount and the coils mounted on that bracket. They don't get shaken around with the engine then like with the factory set up, and there is less chance of broken wires on the coils or modules. You will need longer sparkplug wires then however. Easy to make new ones up as well. JImChuk

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  5. #5

    Join Date
    Oct 2018
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    San Antonio, Texas
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    Default Re: install ignition coils Rotax 912uls

    Your welcome. If you need these scanned send me your email and I can scan and email so you can print easier.

  6. #6

    Default Re: install ignition coils Rotax 912uls

    Thank You So much. I was able to reprint beautifully from your pictures. Also is there anything in your Engine mount instructions regarding lengthening the balance tube between the carburetors?

  7. #7

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    Default Re: install ignition coils Rotax 912uls

    I do not see anything about extending the balance tube but I also do not see anything about switching the manifolds. The pictures in the manual show the carbs and intake in the original inboard position.

  8. #8

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    Default Re: install ignition coils Rotax 912uls

    Quote Originally Posted by T.W. Sullivan View Post
    Thank You So much. I was able to reprint beautifully from your pictures. Also is there anything in your Engine mount instructions regarding lengthening the balance tube between the carburetors?
    Sorry for the late reply, I just saw this question. There is a section on the balance tube and I had been overlooking it. I purchased a balance tube only to remember that it needed extended. I then realized that there was a piece of aluminum tubing in the firewall forward kit that was to be used as the compensation tube. The manual just wants you to run the tube between the manifolds and use rubber fuel line to connect to the fitting on either side. I think I may just use the tube to extend the stock compensation tube since I spent money on it. If you want pics of the actual manual pages let me know and I'll upload them.

  9. #9
    Senior Member Dave S's Avatar
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    Default Re: install ignition coils Rotax 912uls

    T. W.

    One fine point on this modification which I don't think there is a lot of published info on. The ignition modules each have their own ground wire; which, on the uls, are each held by separate bolts to the intake manifold. There have been some modifications where the builder has combined the ground wires and fastened them to the top of one of the coil mounting straps using the strap as a single connection to ground - it's easier that way because a person doesn't have to lengthen the ground wires. What can happen; and what has happened in a few cases, is the bracket cracks taking out both ignitions. It is well to be sure that each ground wire for each module ends up with it's separate link to engine ground to preserve redundancy of the separate ignitions.
    Dave S
    Kitfox 7 Trigear (Flying since 2009)
    912ULS Warp Drive

    St Paul, MN

  10. #10
    Senior Member jiott's Avatar
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    Default Re: install ignition coils Rotax 912uls

    Right on Dave. I have heard of that happening more than once.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

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