Andy Stemple

My Feedback: (11)

So I was having some problems with my DA50 in my H9 Yak. I got tired of messing with it so a few weeks ago I sent it to DA to have them go over it. About $90 later I got it back and they said it was good to go. They replaced some gaskets, diaphragm, bearings, etc. I put it back on my plane and got the exact same results. Here's a breakdown of what's going on.

• Every time I start the engine I need to use the choke, usually I would only need to do this on the first start of the day.
• After a few flips the engine will start and I can run it at full throttle no problem. I seem to have to start it about half throttle.
• After being at full RPM I can easily reduce to an idle and run for as long as I want to.
• As soon as I try to throttle up from idle it acts as if I’m shutting the carb. It will kill the engine if I throttle up quickly or if I try to increase it slowly.
  Here is a list of what I have done/ checked.
• Checked all fuel lines for leaks/ kinks and pressure tested my gas tank. It's a brand new tank and I also tried running a different tank with a direct line to the carb and got the same result.
• I tried three different batteries on my ignition module thinking I could possibly be using an old or worn out pack. Made no difference. Also tried bypassing my ignition switch.
• Checked the throttle servo setting to be sure the carb was opening/ shutting properly.

Here is a link of a video I took of running the engine last weekend. https://www.youtube.com/watch?v=_kzi...ature=youtu.be. The first 50 seconds of the video shows the engine performing decently. After I dropped my camera and get that back up is when the engine starts giving these weird symptoms. For some reason I cannot throttle up without the engine dying. If anyone has any advice I'm all ears. I'd like some feedback before I send it back to DA again. Thanks for the feedback!

dubs1946

Hi, to me that sounds like fuel starvation somewhere, where? your guess would be better then mine.
Try a different clean tank, no filter,new petrol, check your main carry tank for junk in the bottom,and check and clean the small filter in the carb.
Also when it dies on opening the throttle like in the video put a small amount of choke on and see if it will pick up if it does you have a definite fuel drawer starvation problem.
good luck.
Dave.

sparky4lawndart

My Feedback: (10)

Wow.. I had exactly the same problem and it turned out to be the fuel filler valve was leaking air into the system... run a traditional 3 line system to the tank, (carb, fill with a firm fitting plug, and the vent line without kinks/restrictions).

once I changed the tank and got rid of the fuel filler valve I never had the issue again!

kmeyers

OP, you have provided no real information. Prop, needle settings, fuel type, oil type, oil ratio and the list could go on.

Please add some of these to this thread.

Also watching your ignition sensor wire hanging on and off the muffler scares me a bit. Paying attention to details helps engines last.

Truckracer

My Feedback: (19)

Low speed needle too lean. Open until it transitions cleanly to full throttle. Have you actually set the high and low speed needles? Also as suggested, do something with that plug lead banging on the side of the muffler. It will wear through in short order and require repair or replacement.

w8ye

My Feedback: (16)

+1

Andy Stemple

My Feedback: (11)

Thanks for the replies. My first guess was some type of fuel problem. Last weekend I ran a new line straight from the carb directly into a new tank and got the same result.
Prop - 23x8
Oil Ratio - 30:1
Fuel Type - Unleaded 88 Octane
Having just got the engine back from DA I didn't think I would need to be adjusting the carb settings. They assured me that they ran the engine and it worked perfectly there. Before I sent the engine in I actually did adjust the low end needle and could not get a good result. I will give it shot again though and see what happens. I'm about to head out of town so I may not be able to mess with this for a couple weeks but I will post on here once I run it again. Good catch on the ignition wire, never thought of that.

Truckracer

My Feedback: (19)

As has been posted thousands of times before (that is not an exaggeration) you will have to set the needles! No company can adjust an engine to match your fuel mix, your fuel system, your prop load, your altitude, your weather conditions or any one of many variables. DA did a bench run before it left the factory. They didn't adjust the engine on your airplane at your field. That is the owners job.

av8tor1977

My Feedback: (6)

Sometimes I think would should all put this as our permanent "signatures" here in the forum!

I don't know why the (really bad) idea that you don't have to adjust/tune these gas engines is so prevalent. Maybe because nobody bothers adjusting their chainsaws, weedeaters, leaf blowers, etc. for optimum performance??

AV8TOR

Betoperez

I have a da 50 with some similar symptoms and after overhauling the carburetor the engine ran with the same problems. I removed the reed ( petals for DA ) assembly and notice that the reeds or petals were warp I flipped them over and so far the engine is running very well. Not saying that you might have the same problem but it is very easy to check them out and be sure that the reeds are not away from the frame.
I hope this helps.