GSN GIVE-A-WAY Hangar 9 35% Extra 300X Assembly

[Jetpainter]

Thanks for giving us this update. My DA 120 surge is almost gone, but not entirely. It was really bad at first, much like you were actually moving the throttle stick. The only thing that has changed mine was leaning it out a tad at the time.

My only concern is now that I don't really want to lean it anymore as it performs well and you have to take into consideration just how much you are leaning it out. It gets to a point that it is hard to tell just how lean it is. I do see some exhaust smoke once in a while so that is good.

Dave at DA told me that they are doing a carb modification on them for that mid-range surge. I wished I new what that was because I would just do it myself instead of sending the thing back there and waiting so long for it. Maybe he will sell the carb with the mod? I would love to try one just to see what it does.

I'm going to adjust mine with a tach next time out., after that I'll know a lot more about the surge.

 

[Snoopy1]

When you shay you are going to do it with a tack. Do you mean peak the top end with tack and then adjust the low end until the throttle response is the way you like it. And then do the procedure a couple of times until you are happy and then fly it and make minor adjustments as required.

 

[Jetpainter]

When you shay you are going to do it with a tack. Do you mean peak the top end with tack and then adjust the low end until the throttle response is the way you like it. And then do the procedure a couple of times until you are happy and then fly it and make minor adjustments as required.

That's about the size of it.

 

[49dimes]

Just an FYI......When I was running my V1 DA120 I did the "breather tube" mod from the diaphragm plate to about 3mm from the choke butterfly. Maybe the pics are still on FG along with others that did this. Anyway... I thought the custom carb diaphragm covers was supposed to remedy the surging issue? I also understood that a pop off pressure of at least 10psi to 20psi worked best.

 

[Jetpainter]

Just an FYI......When I was running my V1 DA120 I did the "breather tube" mod from the diaphragm plate to about 3mm from the choke butterfly. Maybe the pics are still on FG along with others that did this. Anyway... I thought the custom carb diaphragm covers was supposed to remedy the surging issue? I also understood that a pop off pressure of at least 10psi to 20psi worked best.

View attachment 98098

That is the cover that's on mine.

 

[49dimes]

That is the cover that's on mine.

I would think then the L and H needles are fighting each other in their ability to deliver a "steady flow" at the transition point. Maybe moding the differential pressure "sensing" ports inside the carb bore right about where the main butterfly is what their doing? I don't really know just guessing.

This picture sucks but the ports I speak of are located where the tip of the pencil awl is.....

 

[Snoopy1]

Just an FYI......When I was running my V1 DA120 I did the "breather tube" mod from the diaphragm plate to about 3mm from the choke butterfly. Maybe the pics are still on FG along with others that did this. Anyway... I thought the custom carb diaphragm covers was supposed to remedy the surging issue? I also understood that a pop off pressure of at least 10psi to 20psi worked best.

View attachment 98098

Not trying to fussy but is 14.7 to 15.5 that is ideal for us at sea level. 10 to 20 works don't get me wrong I have had a pope of pressure of over 40 and it kind of worked.
Had the same cover on mine did help on one plane but not the other.

 

[rarcdon]

Luchnia,

I just got my DA 120 carb back from having the modification done to it. I currently don't have the engine in a plane at the moment so you are welcome to give my carb a try. Just let me know and I'll bring it to the field one day. It does come with specific instructions on the new needles setting and notes that you shouldn't monkey with these needles unless absolutely necessary.

I also pick up a set of KS 3086 which they highly recommend for this engine over other choices in the market. They definitely have more volume than the others.

Don

 

[49dimes]

Luchnia,

I just got my DA 120 carb back from having the modification done to it. I currently don't have the engine in a plane at the moment so you are welcome to give my carb a try. Just let me know and I'll bring it to the field one day. It does come with specific instructions on the new needles setting and notes that you shouldn't monkey with these needles unless absolutely necessary.

I also pick up a set of KS 3086 which they highly recommend for this engine over other choices in the market. They definitely have more volume than the others.

Don

Hello Don. Would you mind posting a picture of your modified carb and the instructions that came with it ?

Sounds as if one is to keep "those settings" alone and maybe they set them to your specific location? What concerns me is keeping a decent tune. At my location I'm at sea level but the air density can change in a matter of days during spring and fall causing a need to re tune. And this is with any diaphragm carb engine not just the DA120. Case in point......I tuned a 26cc and 55cc motor on the same day in late spring on a day that was cool (70F) and dry. The next time both engines were operated was about 2 weeks out on a hot (90F) humid day. They both would not start due to the needles being a too lean setting and a re tune was in order to get them running.

 

[Jetpainter]

Hello Don. Would you mind posting a picture of your modified carb and the instructions that came with it ?

Sounds as if one is to keep "those settings" alone and maybe they set them to your specific location? What concerns me is keeping a decent tune. At my location I'm at sea level but the air density can change in a matter of days during spring and fall causing a need to re tune. And this is with any diaphragm carb engine not just the DA120. Case in point......I tuned a 26cc and 55cc motor on the same day in late spring on a day that was cool (70F) and dry. The next time both engines were operated was about 2 weeks out on a hot (90F) humid day. They both would not start due to the needles being a too lean setting and a re tune was in order to get them running.

But they should get richer in hot humid weather not leaner.