tiktock

hi,

my da50 has gone through about 1 gallon of fuel and there are some problems with the engine.

it starts very easily, few flicks with the choke closed and then a few with the choke opened.
after starting, if i shut the engine, it does not start again. i've tried everything but it just doesn't start. ( it's not lean or rich)
some times if i leave the engine alone for about 10 to 15 min and then try to start it, it starts.
if it doesn't start i leave it and try the next day and it starts easily. what could be the reason?

another problem is that once the engine starts and i fly the plane, it's happened twice that the engine has stopped after about 4 to 5 nim in the air.
i was flying at mid throttle and the engine just stops. unfortunately the engine stopped at a bad time and i broke the undercarriage and the bottom of the fuse [:@]
anyway, all that will be repaired, but i don't want this to happen again.

my setup:

the "L" needle on the engine is set at 1 3/8 or 1 4/8 to get rid of the gurgling sound.
the "H" is set at 1 6/8
bally 22x8
oil is Castrol Supper TT @ 32to1
Bisson muffler
plane, WH edge

thanks,

bubbagates

My Feedback: (32)

The symptoms you describe sound like gas is pooling in the reed valve which is something DA fixed in an update. You can give them a call with the serial number from the engine and they can tell you if that particular engine has the correct updates. If not, I think if it's less than 3 yrs old they will do it for free. The down side is you have to send it back to them and wait for it. It will get all of the updates.

JoeAirPort

My Feedback: (41)

Hmm those sound like symptoms of flooding. The gas pooling in the reed block stopped the engine if you landed or grabbed the plane and moved it suddenly while it was idling. It did not cause hard starts with warm engines (not that I know of anyway). A guy at my field had the gas pooling in his engine and it died everytime he landed (or very close to every time).

OK, I just called DA since I have many minutes left on my cell phone (and you live far away). The first thing he asked was if you were choking before the warm starts. In other words you only need to choke once at the beginning of the day. Then after that just turn on the ignition, throttle at idle, and flip it (mine starts the first flip every time when it's warm). So you are more than likely flooding it if you are choking it every time you start it. Also he said to start at 1 3/4 on the low end and lean for a good transition. If your transition is good then you are good on the low end.

The high needle he said to start at 2 turns. Start the engine run it up to full throttle for 15 seconds, if it loses RPM it's too lean. If it does not lose RPM's it's rich (we'll assume it's rich starting at 2 turns). Shut down engine and lean out the high end (1/16). After it cools a little while (2 minutes) start it again. Keep leaning until it starts to lose RPM's. When this happens you have found the peak (actually passed it) . Now richen it to get it to hold constant RPM at full throttle. Find the leanest setting that will make it hold constant RPM for 15 seconds (at full throttle).

Never run the engine more than 30 seconds on the ground so you don't over heat it.

I hope this helped.

RCFlyerDan

My Feedback: (54)

To me, it sounds like a weak battery, where the battery recharges it's self after 10 minutes back up to the required voltage for the ignition unit. You are relating it to the engine being hot, but in reality, the battery is just weak. Overnight the battery has been charged again. Running at higher power settings require more battery power. Make sure your battery is at least 5V. This is just my SWAG! Take Care!

JoeAirPort

My Feedback: (41)

Not a bad theory at all. I guess you have to start simple and not assume anything (like a good battery). You could very well be right.

tiktock

to answer a few of those questions...... the battery is 4.8v but fully charged, i only choke the engine on the first start of the day. the biggest problem in tuning the needle is that if i stop the engine to re-set the needle then it becomes a big problem to start it again so, i have to tune the needle while the engines running. i've gone through a wide range of needle setting,but this problem of not starting after the first start still remains. that's got me thinking that the problem is not in the needle setting.

once i took the spark plug out to see why the engine wasn't starting. the plug was dry, but there was no spark. i rinsed it with gas and still no spark, about 10 mins after rinsing it the spark plug started working. could one of the reason be that there is to much oil in the fuel? is it possible that after a while, some oil deposits on the plug stopping the spark ?maybe the castrol supper TT has to be mixed at something like 40 to 1 or 50 to 1 for it to work? or it just might be that my needle settings are all wrong and I'm very rich. in trying to figure out my max rpm i leaned my "H" all the way to 1 1/4 and even then the rpm didn't decrease. my high end rpm's are 6.66K ("H" 1 6/8)
or it could be that it's an old carb which has not been modified?

exeter_acres

My Feedback: (2)

what is the capacity of the battery???

bubbagates

My Feedback: (32)

After reading the last posts I've got to agree with the battery being the issue. It now appears I had the reason for the pooling in the reed valve incorrect. My apologies

I'm wondering if the battery is capable of taking the load. You might want to load test it but keep the load on it for a little while longer to see what the voltage does.

There is also the outside possibility the ignition has an issue.

Zeeb

My Feedback: (41)

I'm with Dan on this one...

Although it could be the battery, the ignition module may not be happy. I had a similar experience with a ZDZ-50, chased all the "usual" ideas and it turned out to be the ignition module on it's way out. One of the ways that electronic components will fail is with a little heat, i.e. running it for a bit then it won't start. Let it sit for awhile and things cool off then it works again. That is exactly what my 50 was doing and a new ignition module cured it.

That may not be your problem, but it sure sounds like it's a good possibility, especially if you've verified that the battery is not the cause.

JoeAirPort

My Feedback: (41)

Sounds like it's narrowing down.

tiktock

i really hope there is nothing wrong with the ignition module. it would be a pain to send it to DA from India.
anyway, on a good note, the edge is almost repaired and it will be as good as new. i have a 2300mah 6v nimh battery that I'm going to put on the ignition and try to see if it helps. with that battery there shouldn't be any problem with voltage.
also, i found some pennzoil 2T oil which I'm going to try.

i should be able to start the engine in a day or two. any suggestions on where to set the H and L needle?
the outside temperature dues get very hot, around late 30's and in summer it will reach mid 40's
so, i wonder if i should set the needle rich and forget about the gurgling sound for right now.
hopefully the gurgling will go away once the engine is broken in.

exeter_acres

My Feedback: (2)

what size was the battery you WERE using???

a 4 cell pack is enough IF it was enough capacity to supply the required amps

bubbagates

My Feedback: (32)

For those that may need it. Here is a link to the updated DA manual which gives the minimum battery requirements. I also have a DA50 mounting template.

The manual is also available from TBM (TroyBuiltModels)

http://www.hiddenhangarrc.com/da/

From this manual it states:

We recommend a 1500 mAh or larger pack. With this size pack, the ignition pack should last longer than your receiver pack will. If a meter shows 5.0 volts or less, don’t fly. Re-charge. Use a 5.2 to 6.0 volt regulator on packs rated above 6.0 volts.

So, like Exeter, I'm also curious about the size 4.8 pack you are replacing. I use Fromeco Li-ION's regulated to 5.2 volts on mine

tiktock

it was 4.8v, 1500mah pack. it was made by a friend so, just to be on the safe side i'll try another pack and see if it helps.

Zeeb

My Feedback: (41)

I'm not a DA guy, just try to read up on the posts about them since I may give them a try one of these days, but IIRC there are some voltage input considerations for DA. A fully charged 6 volt Ni-Mh can put out more than 6 volts so you may want to verify what the module will take for input voltage.

I know that the older style modules used on my ZDZ's were restricted on input voltage, but the new 100 I have can run off unregulated Lithiums with an input voltage range up to 9 volts.

Maybe you've already checked that, or some of the DA guys will check in on the voltage input question?

edit info:

Looks like some others who know more about it than me checked in while I was typing...

JoeAirPort

My Feedback: (41)

DA sets the high to 2 turns and low to 1 3/4 at the factory. But those are very rich settings for the masses. IMO it keeps engines from getting torched during break in. You could lean the low end for a good transition and leave the high end at 2 turns and see how it runs. The low needle controls 75% of your throttle position. The high needle is the rest. So the low end is very important. Don't worry about gurgling for now, just get the transition to be fast (after a 10 second idle).

Also I think I'd get the engine to re-start after it's been running before ever taking off again. Mine re-starts with a very light flip every time and that's what they should all do.

bubbagates

My Feedback: (32)

The manual does show it will take a freshly charged 6 volt pack at 7.2 to 7.4 volts which drops pretty quickly as soon as it starts feed power and a quick call to Dave at DA confirmed this once I got my first one.

7.4 Volt lithium packs are fully charged at 8.3 to 8.4 volts and take a long time to get down to 7.2 to 7.4 volts and this would cause problems with the DA module. I like the 3W engines because you do not need to regulate the ignition and they even say that it can cause problems if you do

outssider

My Feedback: (23)

i run 1200ma 4.8v ignition pack on da50 after 4... 12 min flights, pack still reads well over 5v.

i don't think it's your needles either...my vote goes to the ignition module as the problem.

Nogyro

My Feedback: (10)

tiktock,

I've had 2 DA50's and both exhibit these same symptoms. I fly by myself a lot, and if I land, refill, and fire right back up, I'm ok. If I let it sit for 5 or 10 minutes then try to restart, forget it. It's not going to happen, especially in the hot summer time. Let it sit for 20 or 30 minutes, one flip and it's going. IMO the engine heats up while sitting, and either looses compression because of it, or the fuel in the crankcase has vaporized. or both. To solve this problem I have a small 10" fan that I set in front of the engine after I land. It cools it down just enough to where I can wait 10 minutes, and restart on one flip. Without the fan, forget it.......Not the needle settings, been there done that. Sounds funny, but that's the only solution I came up with.

ljones5000

My Feedback: (2)

Wow, that must really be a pain. I don't have a world of experience with gas but both my engines start with a flip after the first run of the day. They are not DA but what's the difference? Don't all of them work pretty much the same way?

A lot of talk about ignition voltage...I was thinking they run on 4.8v. Both of mine are 4.8, one on a 2700mah pack and the other on a 2250mah pack. I can leave mine sit in the garage for days on end w/o recharge and they will crank right up, third or fourth flip after choking. Why does DA take 7 volts to crank? Your problem may be with ignition but it sounds like you should have enough battery power to me.

Larry

Zeeb

My Feedback: (41)

In my estimation, this is the key to diagnosing the problem. This is exactly the problem I had, pull the plug and there was no spark until it had sat for 10 or 15 minutes, then it would start sparking again.

I couldn't say why Nogyro is having the problem he's got, but once I got the faulty ignition replaced the engine will start anytime you want to try it. My new ZDZ-100 is the same way, cold, hot or just warm it will still start...

Nogyro

My Feedback: (10)

I did have one ignition fail on me and DA replaced it NC. The engine still acted the same way when trying restarts 5 to 10 minutes after landing. If I was lucky enough to get it started, it sounded real lean for 15 to 30 seconds, then it would straighten up and sound normal. If you tried to set the low needle to compensate for it, then it was extremely rich in the air. Put a little fan in front of it, problem solved. I've got 30+ gallons though the engines, not a break in issue. Still think it's a heat/fuel vaporizing/ring cylinder fit issue....... Got a stock G62 I hand start cold or hot, never acts like this. I know of one other guy that has the same issues with hot starts........

JoeAirPort

My Feedback: (41)

My Moki glows have done that too, you're better off letting them cool off before restarting. They don't like to start when they are already hot (fuel evaporates in cylinder or crankcase?). But I never usually have a problem since I rarely run back to back flights.

Nogyro

My Feedback: (10)

I fly by myself at my own private strip quite a bit so the time line is very often land..........sit for 5 minutes.........then go back up. Most guys don't have this luxury. Not much of a problem when it's like 50 degrees out, but during the summer months when it's 90+, that's when I notice it the most.....

I'm sure the engine builds up heat in the cowl after landing which is the main source of the problem...

MustangFan

My DA-50 doesn't start well when hot either.

If I flip it and it doesn't respond "normal" ... I just wait for 10 minutes or so ... then no problems.