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Engine Bogs in High Alpha

@49dimes I gently stretched the spring under the diaphragm. I read about this on another post and they said to hit it with a heat gun so I did and then cleaned it with denatured alcohol. And when I say I stretched it, I just did enough to notice so I hope it's OK. I might have to see if I can find a complete rebuild kit with a spare spring in it just in case.

Other than that, the screen and everything else looked fine. I just have to reinstall the engine in the airplane and I have the choke set up so the rest should be breeze. I also ordered one of EF's fuel tanks to put in. The water bottle was too long for this one and made removing and reconnecting fuel lines a major pain.
 

49dimes

Damn I'm hungry
@49dimes I gently stretched the spring under the diaphragm. I read about this on another post and they said to hit it with a heat gun so I did and then cleaned it with denatured alcohol. And when I say I stretched it, I just did enough to notice so I hope it's OK. I might have to see if I can find a complete rebuild kit with a spare spring in it just in case.

Other than that, the screen and everything else looked fine. I just have to reinstall the engine in the airplane and I have the choke set up so the rest should be breeze. I also ordered one of EF's fuel tanks to put in. The water bottle was too long for this one and made removing and reconnecting fuel lines a major pain.

Let us know if it helps. The biggest part is getting it tuned like Terry recommended. Like the DA 120.....I'm thinking tuning will be a bit easier once it is fully broke in. As these engines do get close to the break in point the low end usually richens a bit requiring a re- tune. Just FWIW when I re-tune I always put the needles back to the recommended starting point and start from there.
 
So while I was looking up the part number for a replacement diaphragm spring, I noticed that they looked nothing like what I had in my carb (I.E. they were shorter).

I called a local outdoor equipment dealer and asked about a Walbro diaphragm spring and they said they had it. I told them it was for an HDA carb and the guy just said "yeah..."

I took my carb with me when I went to pick it up and spent a whopping $0.60 on it. The pic below is the spring that is my carb originally after the slight stretch on top, the new spring, and a spring from a WB that I was curious how it compared (it's a smaller diameter spring). After seeing this, I began to wonder if my spring was defective (it happens) so I rebuilt the carb with the new one. I also took off the velocity stack from the motor and put in one of the FlowMasters from EF. The water bottle I was using was too long to make the connection from the front of the tank to carb a pain to remove.

So I took my Edge with the new set up out to the field today. I found that if I choked the motor it would start but wouldn't transition to anything past 1/3 stick and then quit (I.E. too lean). So keeping @Terryscustom guide to tuning in mind, I kept richening the low until it transitioned. I finally got it to the point where it would transition but the idle was a little rough so I killed the motor and richened the low a little bit more. When I restarted the idle was better and it still had a nice transition so now it was time to test it out. I took off and flew around with 0 problems. I first tested inverted downlines and no hesitation or bogging so then I tried knife edge and then rolling harriers (all high up) with no problems. The only problem was the throttle curve was different. I had a linear curve before with the velocity stack so I landed, adjusted and went back up.

After landing, I shut down the motor and checked the temp. It was around 180F. Just to double check my low, I richened it 1/8 of a turn. Next flight, again no problems until I was harriering around for a while and then went high and came down at idle. I started to pull up to check the transition and it started to go but then died. I was high up so I landed OK. Checked the cylinder temp and it was around 160F. So my guess is that the engine loaded up and then the idle was a little too low from the rich condition and died. Took out the 1/8 of a turn on the low and went back up. I flew around for over 12 minutes at a high altitude constantly testing. Transition in straight and level was perfect and then I tried going from idle to full power on both 45 and straight uplines. Transition was still good and maybe a very slight on the straight uplines which was to be expected. At the end of the flight, I put it in a hover and punched it. Engine revved up and no problems pulling out.

Cylinder temp was back to around 180F at the end of the 3rd flight. So it seems I finally have this thing running right.
 

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I'm just glad I got it working right. I never would've thought to check the diaphragm spring without posting about it. I was almost to the point that I was going to sell it and probably go electric.
 
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