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H9 15cc Carbon Cub

Discussion in 'Giant / Scale ARF Build Threads' started by AKNick, May 8, 2016.

   
  1. AKNick

    AKNick 100cc

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    15x6 to 16x8 recommended.
    But it's cute watching it try
    I believe your on to something, I tried the larger prop to see if it would help my idle which it did but it probably compromises my transition.
    Just tried the extreme adj to verify rich or lean. I normally do the screw driver blade trick if that.
    Ever play with pop off pressure? Might try checking my lever height and maybe stretching the spring a nano bit. Curious if the lack of fuel pressure is not letting it transition quickly. Wish I had a pump to see where it's at.


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  2. AKNick

    AKNick 100cc

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    [​IMG]
    [​IMG]

    Found the diaphragm lever was kind of low. So I adjusted it to flush and a smidgit more.

    This makes sense because my needles were 2 1/8 turn out roughly, so I'm guessing it wasn't getting enough fuel, hence why it would die from idle to WOT.

    http://www.walbro.com/tech-tips/metering-lever-setting/

    Plugs still good, timing still about 30, and switching back to the 16x8

    No time to run it today, but will give it a whirl tomorrow.


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  3. AKNick

    AKNick 100cc

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    With the wood 16X8 I had on originally the new needle settings are 1 5/8 L and 2 1/8 H, Still acts lean when at a idle to WOT, idle is on the high end. Idle will load up after about 15+ sec which sounds like it could be a tad rich. Tried to lean out the top end a bit, but then goes into a lean rpm fade about 2 turns out in 8-10sec, so it'll stay at 2 1/8 H.
    Overall, adjusting the lever to just barley above flush did something for the Low end not requiring as much fuel through the needle, but still over 1.5 turns out. after more extensive research I found a RCGF thread where multiple people have run into this issue on 15-26cc RCGF engines with a fake walbro. The fix was fine tuning the fork/lever. One individual had to mess with it about 4 times and it will transition, and run like it should. I noticed that the fork attaching the needle (other side of the lever) has a fair amount of play in it. I am going to take it apart again and adjust the fork so there is very little play in it.

    The lever height for my specific carb (different than my DLE35RA!) is set so that with a strait edge set on the bosses next to the lever, the strait edge should just touch the lever without lifting the needle:

    full-2772-14985-walbro_wa_metering_lever_height.png

    This is from the link I had posted earlier:
    "Setting of the metering lever height for a diaphragm carburetor is one most important adjustment to be made in a diaphragm carburetor. The metering lever’s functionality starts with the atmospheric pressure entering from the vent hole in the metering cover. This atmospheric pressure forces the metering diaphragm assembly down while the low pressure (vacuum) under the metering diaphragm helps to draw it down onto the lever. The lever is depressed, over rides the metering spring and lifts the inlet needle off the inlet seat to allow the fuel mix to enter into the metering chamber of the carburetor. The correct metering lever setting is critical. A lever set too high can cause the metering diaphragm assembly to contact the lever too early and create a rich condition. If the lever is set too low, a lean condition can occur due to the length of travel the metering diaphragm assembly has to make to contact the lever. Our C-1022 Service Manual shows you and walks you through the proper procedure for setting the metering lever height by using the Walbro 500-13 metering lever gauge."

    MeteringSystem593x444.png

    For now: meter lever is set where it should be now, and it improved my transition, but with the HSN set so rich and the motor acting like it's starving when attempting to lean it out to what should be a mfgr setting of 1.5 out (which should be on the rich side!)- I am led to believe that the fork adjustment should allow the extra needed fuel into the metering chamber so when moving to WOT the carb will give a bolus of fuel thus acting like an accelerator pump found on larger carbs to mix in with the extra air being sucked up by this little beast. There is also the possibility that the lever spring is too strong so it would take more differential pressure for the diaphragm to overcome the spring tension for demand of fuel through the carb vacuum as well. Im feeling more confident that I'm getting this thing figured out, maybe tomorrow I'll have the results I am looking for fingers crossed. Class is over for know ha ha (teacher=interwebs)
     
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  4. AKNick

    AKNick 100cc

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    What ever I did it helped! Still a slight hesitation when slammed from idle to WOT. But the low is about 1 turn out, high is about 1 3/4. It's running reliably enough where It's time for a flight. I checked out the rcgf manual again and it said average mixture settings are 1 1/4 L and 1 3/4 H now doesn't that sound pretty close to normal! Wohoooo


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  5. AKNick

    AKNick 100cc

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    Got some gopro footage. not that exciting, but its a video!

    3:35 dead stick while in a knife edge with no cowling, guessing air blew into the diaphragm.

    4:28 bunch of short clips of passes
     
    Last edited: Apr 13, 2017
    Terryscustom and pawnshopmike like this.
  6. Sounds like she's running pretty good now.:way_to_go:
     
    AKNick likes this.
  7. Terryscustom

    Terryscustom 640cc Uber Pimp

    Nice, that does sound way better than a single 20cc.
     
    AKNick likes this.
  8. AKNick

    AKNick 100cc

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    So i figured out what was going on with my flaps. I had a 7ch receiver in which I had no option but to use a servo reversing Y-harness:
    http://www.headsuphobby.com/MPI-Digital-Miracle-Y--Servo-Reversing-Y-Adapter_p_1142.html
    It failed on one lead only - plug the servo into the other lead and it works perfect. so somewhere in the signal it doesn't compute. Anybody have an alternate Idea? I have switched leads on the motor before for analog servos, would this work on a digital servo ok?? maybe @Xpress ? Any thoughts there? I know I know they are Savox... lol.
     
  9. Xpress

    Xpress GSN Sponsor Tier 1

    Can't speak for Savox, but on our digital servos you cannot reverse the servo direction by swapping motor/pot wires, only on Analog servos @AKNick
     
  10. AKNick

    AKNick 100cc

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    Ok thank you


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