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Thread: CarbMate P-sync tool description

  1. #11
    Senior Member jrevens's Avatar
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    Default Re: CarbMate P-sync tool description

    Quote Originally Posted by Birdseyeview View Post
    John, I appreciate your suggestion about your rpm choices during the P-sync. From your response it sounds like you are also using a CarbMate. When you get a "REF" or "CARB2" reading that needs adjustment what logic do you apply to determine what direction the applicable throttle cable is to be moved?

    I've also been trying the P-sync while the engine is running and my Kitfox 6 has the short cowl (same as the series 5) which puts me even closer to the spinning prop. I get very nervous during that operation and have been trying to rush through it, which may be why I've had some trouble with the P-sync. I plan to try again soon, take my time and be more methodical about it.

    I'm not really sure, Larry. I've just started moving it in one direction, and if no change occurs I go the other way. I think you could probably put some pressure in the middle of the exposed cable with your finger and see if it makes an improvement. That would have the effect of shortening that cable without affecting the other carb's cable, and tell you what way to go (if that makes sense to you).
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
    EAA Lifetime
    Chap. 43 honorary Lifetime

  2. #12
    Birdseyeview's Avatar
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    Default Re: CarbMate P-sync tool description

    Guys - SUCCESS finally, All your suggestions paid off because they helped me to better understand the entire sync process and the basic operation of the CarbMate tool, both of which were new to me. I didn't do the bowden cable adjustment while standing next to the spinning prop because it just made me too nervous, and I was doing it all by myself. As a result, the sync process took several adjustments with multiple engine starts and restarts, but I got lucky when my initial adjustment happened to be in the direction it needed to go. My 912 is finally purring like I suspected it should with no vibration at idle, or at any other rpm that I tried. It starts very quickly and I'm not getting any hint of the carb venting that plagued me a month ago before I flushed all the BSS out of my carbs and all the other fuel system components. During the hunt to find the real culprit responsible for rough running and carb vibration I have discovered that there are many potential causes. When I began to check for and test for each possible cause they were all eliminated one by one until todays victory. I've said it before and I'll say it again - I love this forum because its contributors have helped me identify all the potential causes for the various issues I've seen and what to do about each one. Thank you all.
    Larry Olson
    Kitfox Series 6 - 1st Flight Oct 2021
    Tri-gear, smooth cowl
    912 ULS

  3. #13

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    Default Re: CarbMate P-sync tool description

    I don't want to stand directly behind a spinning prop to tweak my carb sync settings either! So I tie a long piece of monofilament fishing line to each of the two throttle arms and run each line back into the cockpit. Plumb the sync gauges (or CarbMate) into the cockpit as well. Then you can safely sit in the cockpit while the engine is running, set the RPM as desired, and pull on each monofilament line individually to determine which throttle arm needs adjustment. Then stop the engine, tweak the appropriate throttle sheath cable nuts, and repeat the process as required to bring the two carbs into sync.

  4. #14
    Senior Member jiott's Avatar
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    Default Re: CarbMate P-sync tool description

    Assuming the mechanical sync is fairly good, I have always found that you can choose either carb, whichever is the most convenient, to do the adjusting. It is never a certain carb that is out of adjustment, it is just that they are not both the same. So you can adjust either carb to bring it into sync with the other. This is nothing new to most of you, but maybe it might help some newbies.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  5. #15
    Senior Member jrevens's Avatar
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    Default Re: CarbMate P-sync tool description

    Quote Originally Posted by jiott View Post
    Assuming the mechanical sync is fairly good, I have always found that you can choose either carb, whichever is the most convenient, to do the adjusting. It is never a certain carb that is out of adjustment, it is just that they are not both the same. So you can adjust either carb to bring it into sync with the other. This is nothing new to most of you, but maybe it might help some newbies.
    Good point Jim!
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
    EAA Lifetime
    Chap. 43 honorary Lifetime

  6. #16
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    Default Re: CarbMate P-sync tool description

    I know this post is about using a carb mate tool, but I'll throw this into the mix incase some one reading these messages is wondering what to buy to sync their carbs. I've been using a single vacuum gauge with a T in the line coming into the vacuum gauge. Each line going away from the T has a valve in it. Those lines then go to the ports on the intake manifolds. With it all hooked up, open one valve and you see the vacuum there. Close that valve and open the other and see if both readings are the same. Adjust the linkage so they are reading the same. Even if the vacuum gauge isn't accurate, you will still be able to compare one side to the other, and that's what you are really trying to do. JImChuk

  7. #17
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    Default Re: CarbMate P-sync tool description

    I use a twin engine manifold gauge. I found it to be more finite than the carbmate.

  8. #18
    Birdseyeview's Avatar
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    Default Re: CarbMate P-sync tool description

    I have created a 2 page WORD document that captures the step by step process I used to do the carb sync on my 912 while using a CarbMate. It isn't meant to replace the Rotax manual or their video describing the sync process, but is to supplement them with details not included by Rotax. If anyone would like a copy send me a private message including your e-mail address and I'll send you a copy.
    Larry Olson
    Kitfox Series 6 - 1st Flight Oct 2021
    Tri-gear, smooth cowl
    912 ULS

  9. #19

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    Default Re: CarbMate P-sync tool description

    Quote Originally Posted by avidflyer View Post
    I know this post is about using a carb mate tool, but I'll throw this into the mix incase some one reading these messages is wondering what to buy to sync their carbs. I've been using a single vacuum gauge with a T in the line coming into the vacuum gauge. Each line going away from the T has a valve in it. Those lines then go to the ports on the intake manifolds. With it all hooked up, open one valve and you see the vacuum there. Close that valve and open the other and see if both readings are the same. Adjust the linkage so they are reading the same. Even if the vacuum gauge isn't accurate, you will still be able to compare one side to the other, and that's what you are really trying to do. JImChuk
    I used this procedure just last week, rarely are two gauges exactly the same. Using the valves to limit gauge flutter is helpful as well.

  10. #20
    Birdseyeview's Avatar
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    Default Re: CarbMate P-sync tool description

    Quote Originally Posted by ScottS97385 View Post
    I used this procedure just last week, rarely are two gauges exactly the same. Using the valves to limit gauge flutter is helpful as well.
    Scott, This is a great idea and fairly easy to create such a tool. I wish I had heard about it before I bought the Carbmate. Thanks for the input.
    Larry Olson
    Kitfox Series 6 - 1st Flight Oct 2021
    Tri-gear, smooth cowl
    912 ULS

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