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A friend just performed the 5-year rubber replacement on his 912iS and went with the silicone hoses.  Can anyone explain why the original 1” rubber hose 822450 that exits the expansion tank has protective mesh but the silicone replacement 822454 does not?  An interesting point is that the mesh on the rubber hose he removed was almost completely worn through on one spot.  Anyone have any insights on this?

  • Re: Rubber Hose Replacement

    by » 3 months ago


    Bob,

    I think the mesh is more for heat shielding than abrasion protections. Mine was about worn (or melted) through at 5 years also. I used the Rotax 822450 rubber hose when I replaced mine but added a piece of silicon fire sleeve wrapped around the lower third of hose (over the mesh) where it rests on the top of cylinder 4. I think the new silicone hose will probably hold up fine without the mesh.  However, I might be tempted to smooth the top edges of the cylinder 4 cooling fins with some 400 sandpaper where the silicone hose rests on them. 


  • Re: Rubber Hose Replacement

    by » 3 months ago


    Thanks, Jeff.  My concern is that I’ll be doing my replacement here too within the year.  My friend has that wear with less than 150 hours.  I’m at just over 400 so a bit concerned about how mine looks. This might cause me to accelerate my hose replacement timing.  And he did add heat shrink mesh to his as a precaution.  I plan to do the same and may well include your suggestions too.


  • Re: Rubber Hose Replacement

    by » 3 months ago


    All our engines are done such that the hoses rub on nothing. Put stand offs and tie the hoses so they cannot rub.


  • Re: Rubber Hose Replacement

    by » one month ago


    Hi Glenn

    On the iS engine there is a 1” hose that routes under the airbox and over cylinder 4. It’s a tight fit because the hose fills the space and there is no way to stand it off of or tie it away from resting on the top of the cylinder cooling fins. This is a form hose and it comes with a fabric type heat protector over that section of hose, but it does not quite seem to fully protect it.  I’ve not seen one fail, but the hose often has a small area of heat damage when inspected.  The only thing I have come up with is a small piece of silicone fire sleeve used as a pad between the cylinder and hose.  If you have a better idea for that particular hose I would like to hear it.  


  • Re: Rubber Hose Replacement

    by » one month ago


    Jeff, I asked my friend to take photos of the wear area on his hose.  The wear, not burn, is on the top of the hose.  This appears to be different from what you experienced?  If so, maybe I need to add reinforcement to the top and bottom.  But as you cited above, there’s little space to work with around this hose.

    38913_2_IMG_1533.jpeg (You do not have access to download this file.)
    38913_2_IMG_1534.jpeg (You do not have access to download this file.)

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