Kitfox Aircraft Stick and Rudder Stein Air Grove Aircraft TCW Technologies Dynon Avionics AeroLED MGL Avionics Leading Edge Airfoils Desser EarthX Batteries Garmin G3X Touch
Page 3 of 11 FirstFirst 1234567 ... LastLast
Results 21 to 30 of 104

Thread: Precision tuning the Rotax 912 UL/ULS

  1. #21
    Senior Member Delta Whisky's Avatar
    Join Date
    Dec 2017
    Location
    Amissville, VA
    Posts
    637

    Default Re: Precision tuning the Rotax 912 UL/ULS

    Congrats on getting back in the air and the AF ratios you have been able to set up. As soon as my new muffler is received I hope to do the same. Because I plan to follow in your foot steps, I do have to ask a question that is based more on my lack of knowledge about Rotax engines than anything else. Assuming that both of your reported AFRs are at cruise RPMs, why are you not pleased with 14.1:1 at 4800 rpm? You are still a tad rich of stoichiometric and (I'm assuming) not pulling so much power that additional temperature or timing control is needed. Thanks.

  2. #22
    Senior Member Slyfox's Avatar
    Join Date
    Dec 2008
    Location
    felts field, spokane
    Posts
    1,327

    Default Re: Precision tuning the Rotax 912 UL/ULS

    Quote Originally Posted by AvDES LLC View Post
    What do you have the float armature set to? Try 13.5 mm and make sure to do a full throttle grind run up before taking off. Run up for well past a climb out duration to make sure the carbs are refilling quickly enough after the adjustments
    right now at stock. I've had so much trouble with these floats the last few months, now they are getting real bad, grounded until the floats come in. This thing will sit there not running and start leaking out the right carb, turn on the facet pump and starts pouring out. If I let it set a day with the fuel off and pull the bowl it will be about out of fuel in the bowl. I think it's soaking up into the floats. The other day I took the floats out of the left carb and put them in the right, took a set of floats that I had from years ago and put them in the left. I turned the fuel on and the facet pump, made sure the fuel was up all the way in the bowls. let it set for a couple days and check that right carb, fuel still at the proper level. stinkin' floats bad for sure there. now to set and wait for the blue ones. yes I'll set it to the 13.5mm thanks.
    steve
    slyfox
    model IV 1200-flying
    912uls
    IVO medium in-flight
    RV7A-flying
    IO-360
    constant speed prop

  3. #23

    Default Re: Precision tuning the Rotax 912 UL/ULS

    Quote Originally Posted by Delta Whisky View Post
    Congrats on getting back in the air and the AF ratios you have been able to set up. As soon as my new muffler is received I hope to do the same. Because I plan to follow in your foot steps, I do have to ask a question that is based more on my lack of knowledge about Rotax engines than anything else. Assuming that both of your reported AFRs are at cruise RPMs, why are you not pleased with 14.1:1 at 4800 rpm? You are still a tad rich of stoichiometric and (I'm assuming) not pulling so much power that additional temperature or timing control is needed. Thanks.
    thank you sir - its been a hell of a time and im glad the big fight is behind me and the rest is just fine tuning. Now in regards to the 14.1:1 ratio - that is actually showing us that we are in a lean condition, which is why I am interested in tuning that out a bit further. If I were sitting in a slightly rich scenario (12.8 or below) then I wouldnt pay much mind to it as we rarely spend alot of time at the 4800 RPM range. My reasoning behind stating the fine tuning is worth the time is that lean conditions tend to destroy things and can result in some pretty bad things happening inside of the engine. That said, ill be spending a bit of time with this needle jet circuit to try and get these final lean conditions sorted out. I HIGHLY recommend welding in that AFR bung and spending a bit of time in the plane with all settings as they were before you did the AFR meter install and see where your engine was at according to those settings - you may be surprised.


    Slyfox, While youre in those carbs, you may want to consider replacing the float needles as well. And while youre in there replacing those float needles, it may be good to polish the needle seats in the carbs themselves. You can do this with a hand drill, a few q-tips, and some metal polish - there are tons of videos on youtube that explain how to do this but lemme know if you cant find them and ill gladly do a small write up for ya.

  4. #24
    Senior Member jrevens's Avatar
    Join Date
    Aug 2009
    Location
    Arvada, CO
    Posts
    2,146

    Default Re: Precision tuning the Rotax 912 UL/ULS

    What kind of fuel are all you guys using… 100LL, 91 oct. ethanol-free mogas, 10% gasohol, or? Adding Sta-Bil to the fuel?
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
    EAA Lifetime
    Chap. 43 honorary Lifetime

  5. #25
    Senior Member Slyfox's Avatar
    Join Date
    Dec 2008
    Location
    felts field, spokane
    Posts
    1,327

    Default Re: Precision tuning the Rotax 912 UL/ULS

    Slyfox, While youre in those carbs, you may want to consider replacing the float needles as well. And while youre in there replacing those float needles, it may be good to polish the needle seats in the carbs themselves. You can do this with a hand drill, a few q-tips, and some metal polish - there are tons of videos on youtube that explain how to do this but lemme know if you cant find them and ill gladly do a small write up for ya.[/QUOTE]


    yes I did all that already. the floats are the last thing, should have been the first. lol
    steve
    slyfox
    model IV 1200-flying
    912uls
    IVO medium in-flight
    RV7A-flying
    IO-360
    constant speed prop

  6. #26
    Senior Member PapuaPilot's Avatar
    Join Date
    Nov 2013
    Location
    Nampa, Idaho
    Posts
    1,225

    Default Re: Precision tuning the Rotax 912 UL/ULS

    Shouldn't this discussion be in the "Engines" section?
    Phil Nelson
    A&P-IA, Maintenance Instructor
    KF 5 Outback, Cont. IO-240
    Flying since 2016

  7. #27

    Default Re: Precision tuning the Rotax 912 UL/ULS

    probably. This thread didn’t start with this title or intention but evolved into a 912 tuning thread rather quickly. Maybe a mod can make that happen when they’ve got a free moment.

  8. #28
    Super Moderator desertdave's Avatar
    Join Date
    Jun 2019
    Location
    Scottsdale AZ
    Posts
    304

    Default Re: Precision tuning the Rotax 912 UL/ULS

    Quote Originally Posted by PapuaPilot View Post
    Shouldn't this discussion be in the "Engines" section?
    Quote Originally Posted by AvDES LLC View Post
    probably. This thread didn’t start with this title or intention but evolved into a 912 tuning thread rather quickly. Maybe a mod can make that happen when they’ve got a free moment.
    Boom!.......... Moved to the engine section.
    Dave
    KitFox 6 Taildragger
    912 ULS
    Whirlwind 70” Prop
    Garmin G3x
    All around nice guy

  9. #29
    Senior Member Delta Whisky's Avatar
    Join Date
    Dec 2017
    Location
    Amissville, VA
    Posts
    637

    Default Re: Precision tuning the Rotax 912 UL/ULS

    Quote Originally Posted by jrevens View Post
    What kind of fuel are all you guys using… 100LL, 91 oct. ethanol-free mogas, 10% gasohol, or? Adding Sta-Bil to the fuel?
    100LL with Decalin.

  10. #30

    Default Re: Precision tuning the Rotax 912 UL/ULS

    Quote Originally Posted by desertdave View Post
    Boom!.......... Moved to the engine section.
    Thank you much!

    As far as fuel - ethanol free only - i avoid 100LL like the plague whenever possible - not good for the human body, environment, or the rotax.

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •