PiccoLino

I have been flying for a couple of years a YAK 54 on which I have mounted a DLA 56, turning a 22x10 scimitar Master Airscrew propeller. Klotz Synthetic oil 33:1. 7000 RPM, not a single problem. Then one day the engine just refused to start. I checked the usual things, such as ignition, battery pack (4x1.2 Volts NiMH), fuel line, carburetor filter, rubber diaphragm, etc..
The engine starts only in this way: I turn the plane upside down, I pour 10-20 cc of fuel through the stock exhaust, turn the plan back to upside, flip the propeller and OK.
Then I can fly, on a very satisfactory throttle response with no engine stops just like the best engines around.
Then, assuming that it could be the carburetor, I bought one of those replacement set and I changed everything inside my Walbro. No result.

Has anyone an idea of what it could possibly cause such a inconvenience?

Thanks for your help,

Franco

karolh

sub

AirWizard

My Feedback: (3)

Have you checked the reeds?

karolh

Does this only happen on the first start of the day, or does it happen every time you try to start the engine ??

closetguy

My Feedback: (13)

I had the same trouble with my DLA never could get the carb to run rite from day one.i just bought a DLE carb off ebay,that took care of it.
but just to be sure check the reeds for chips or cracks and laying flat.

PiccoLino

It only happens on the first start of the day, then by the first or second propeller flip it fires up and keeps like that until I go home.
I have checked the reeds but I am not familiar with it so I don't know how they are supposed to look like. They are quite rigid, no cracks, fixed in place but they don't close (firmly touch) the square openings when resting.
If it was the reeds, why after the first start isn't the engine stubborn anymore? May it be because the reeds warm up then and get more flexible? Or is it because once the fuel got to the carburetor, the propeller flipping doesn't need to generate that much of vacuum force to bring some fuel into the combustion chamber? What could it be the testing situation that would confirm that it is the reeds?

Franco

closetguy

My Feedback: (13)

the reeds need to lay flat on the reed block,that is what makes the engine pull fuel to carb.and you realy need them to lay flat and make a good seal on the first start up.

PiccoLino

So it is likely the reeds because two of them don't really lay flat on the block, very close but not touching. Do I have to replace them or is there a way to fix the thing? And, if I have to replace them, should I go for original spare part or buy some higher quality one?

3136

Take the reeds off the cage,</p>

 get a flat surface and lay some fine sandpaper on it </p>

then gently sand the surface of the cage so it's perfectly flat.</p>

Re assemble the reeds, turn them over the other way, or buy new ones.</p>

You can sand the insulator block flat too while you have it apart</p>

karolh

For a flat surface when sanding the reed cage use a piece of glass and some 400 grit emery paper

dla_engine

<div style="margin: 0cm 0cm 10pt"><span style="color: #0000ff"><span style="font-size: larger">Hello <span style="line-height: 115%">Franco,</span></span></span></div><div style="margin: 0cm 0cm 10pt"><span style="color: #0000ff"><span style="font-size: larger">Thanks for supporting DLA engines. Please accept our apologies for this inconvenience.</span></span></div><div style="margin: 0cm 0cm 10pt"><span style="color: #0000ff"><span style="font-size: larger">We noticed that you have already flown this engine for a few years, we are afraid that the engine you have is our previous version. From your description, it can be primarily concluded that the problem may cause by a not fully closed admission valve. We would like to offer some suggestions to you: please polish the valve by using a fine sand paper, we do believe that will help. This problem has been solved long time ago, now our admissions are CNC machined, they looks very smooth and closed very well.</span></span></div><div style="margin: 0cm 0cm 10pt"><span style="color: #0000ff"><span style="font-size: larger">If you cannot solve the problem, please try to contact the dealer, they will help you out. If not, please email to us directly, our email address is </span></span><span style="color: #0000ff"><span style="font-size: larger">[email protected]</span></span></div><div style="margin: 0cm 0cm 10pt"><span style="color: #0000ff"><span style="font-size: larger">Any further problem, please feel free to contact me. </span></span></div><div style="margin: 0cm 0cm 10pt"><span style="color: #0000ff"><span style="font-size: larger">DLA Team</span></span></div>

PiccoLino

I have made the reeds job as you guys have kindly explained: super flat surface, 400 sand paper and flipped them. I am also quite confident that this is going to be the solution. Let's see this Sunday.

For now, thanks a lot again,

3136

If they seat well you can test (roughly) without running.
Put the throttle on full, turn the choke on and flip the prop back and forth quickly (without going through compression) .
You should hear them go pop pop vairly loudly.
That's a quick but rough test you can use at the field when trying to diagnose a problem without pulling it apart.