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I have several questions/issues that I need help with, but will post one at a time.

I have owned my Rotax 912S powered Titan Tornado II for about 3 years. I have been dismayed about Exhaust gas temperatures being different between the right and left side, and had tried several things to remedy the problem. At cruise settings above 5200 RPM the difference would typically be about 60 Deg. F. But below that RPM and down to 4000 RPM I could see as much as 100 Deg. F. difference.

One day this last winter I changed the configuration of my carb vent hoses and miraculously at climb out power the EGT between the two sides was identical. Below 5200 RPM I wouldn't see much more then 30 Deg. Difference.

To test it to make sure it wasn't some fluke, I returned the vent tubes to their original positions under the carb bowl clips, and the old EGT temps duplicated themselves. I returned the vent hoses to their new positions (left pointing straight down and attached to the fuel line entering the carb; the right side also pointing straight down and attached to a convenient hose--lengths of the vent hoses are 5 inches). The sweet EGT temps returned.

I have been flying for approx. two months and have been elated to see the right and left side EGT temps so close, and thought I had my problem licked until this weekend. With the vent hoses in the new positions my EGT variation woes have returned.

Anybody have any idea what might be causing the EGT differences? Temperatures have been rising due to the season change, could this have anything to do with the problem?

Following the Titan Tornado Group on Yahoo I noted that a year or so ago some suggested venting the vent tubes into the air cleaners. Has anybody done this? Can you give me any details like how far from the carb inlet, how far into the air filter, etc.??

Thank you.
  • Re: EGT Woes

    by » 10 years ago


    I have vented my carburetor vent lines into the very back (down low) of the air cleaners. Have been running this way since new-now about 90 hours. No problems. My EGT temps do vary by about 100F but have not worried about it. The reason I connected the vent tubes to the air cleaners is that this is exactly the plumbing you have if you install the Rotax airbox. It also prevents any occassional fuel drip from dropping down on the hot exhaust.

  • Re: EGT Woes

    by » 10 years ago


    0F to 80F can be normal depending on your setup, carb health and throttle setting. A bad carb sync will affect temps or a needle clip in the wrong position. If I see 100+F I start to wonder whats going on. It could be something simple, like a wire, bad connection, bad EGT probe. It can even be header wrap cloth that covers an EGT probe. For some reason header wrap cloth has something in it that causes swings of 60F-120F and quite rapidly. I talked to Dynon and Rotax and neither had an explanation. I have duplicated this several times so it can happen. If you wrap your exhaust, wrap up to, but not over the EGT probe then start back up on the other side. It could be a throttle cable that has a little friction and now doesn't perform like it used to. It hangs up ever so slightly.

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


  • Re: EGT Woes

    by » 10 years ago


    Thank you James, and Roger for your reply's. I don't have any heat wrap, and what is so perplexing is that for two plus months I had those EGT temps nailed. I'm wondering if something has changed in the vent tubing like a cable tie restricting one or the other with use, or something.

    James,
    Please give some more detail about your vent tubing into the air cleaners. You indicated that you have run your lines in low. Are they directly under the intake side of the carb, or if you use the clocking method are they 3 o'clock, 4 o'clock, 5 o'clock, etc. as viewed from the intake side of the carb? And are they low enough to be next to, or almost on the inside diameter of the air cleaners?

    Thanks,
    Ron

  • Re: EGT Woes

    by » 10 years ago


    My vent lines go directly into the back of the air cleaners at the 6:00 position. The holes are drilled thru the rear rubber cap low down so the hole emerges on the inside at the low point of the inside diameter. This keeps the vent line from going uphill. The hole is tight enough so the plastic tubing stays in by friction.

  • Re: EGT Woes

    by » 10 years ago


    Thanks James,

    Just one more question. How far into the air cleaners do you go with the vent lines?

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