well let us know how you make out i hope mine will fire up in april but the soup kitchen may evict me before then.

Here is what DA said when I ask about the update to the engine for the idle problem.

There are actually two ways of fixing the problem that you are talking about. The first way is to lean out the low end about another 1/16 of a turn, and that should do it. If you still seem to have the problem you can send the engine to us and we can update it for you. Basically what the update consists of is a change in location of the crank case pressure. By changing that position the fuel is not allowed to puddle up in the carb block like it used to.

Id like to know why some are having problems and some are "NOT". My self have "NOT" had this problem with the 2 da 50's i have. Is this all in the low end setting.

Mine came last Friday the 12th and the serial number is 2814.

It has the update:

I see they fliped the carb 180deg. as well.

Wonder what happens if you move the pulse line, but don't rotate the carb 180 degrees? That means redoing linkages if the engine is already mounted. []

The carb doesn't care which way it's mounted...Use a longer pulse line and leave the carb where it was...No big deal, the pulse line length is not critical....

Well that's what I thought, but I doubt if Dave rotated it by accident.

If they used a reed block that had a hole in it that lined up with a pulse hole on the Carb face that would solve ALL these issues. Thats they way many Chain Saw Mfgs do it. Or at least did so in the past. I am familiar with the engine that was described in the original post. I don't think tweaking the carb solved any thing in that case. As to why ALL the engines don't exhibit the same symptoms I can't say other than there are some variences in manufacturing, ambient conditions, fuel, oil etc.

And therein lies the problem...The hole in the carb for the pulse is usually not in a good place to line up with a hole that could be drilled through the reed block...The reed block with a hole it it is the cause of some of the problems with the RCS 140..the thin aluminum plate under the carb bends..A bent plate doesn't seal well and the pulse leaks out..No pulse, no pump..A fitting somewhere in the case, or even in the transfer port, is a better way to get the pulse to the carb...The chainsaw carbs DA uses are made just that way, the hole for the pulse is not drilled out in the carb body and the backplate has a fitting in it...Many of the carb inslulator blocks don't have enough space under for the carb to route the pulse to the hole in the carb...The rotator blocks made for the Zenoah engines are a good example, the pulse passage in the block is within 3/64' of the center hole..Any mismatch between the gasket and the hole results in a pulse leak and less than adequate fuel pumping....With a fitting in the case the carb gets the full pulse all the time, even if the carb is slightly loose on the block..
I have tried some different ways to route the pulse to the carb, always came back to the fitting in the case on most engines...
Another way to do it....Make a lathe fixture to hold the carb so the bore is centered...Turn a 360 degree groove about 1/16 wide in the base of the carb about 1/16 deep, with a diameter that would cover the pulse hole.. The pulse hole will get the pulse no matter which way the carb is rotated..Would take only about 30 seconds once the fixture is set up and the groove tool made..You could do 100 carbs in a short time...
BUT...The carbs would have to be the ones with the pulse hole already drilled in the base..(Most are)

I just spoke to Dave and he says that he will modify my two DA50's (#410, and 411). I asked if he will be flipping the carb on me as I told him I saw a photo on the internet showing his latest engine.

He said he would indeed be flipping it over unless its a problem for me with linkages etc. He continued to say that if its already been mounted to an airplane then he can try to something else.

Given what he said I have to assume that he inverted the carb for a reason.....

RCIGN- I'm with you....I can't imagine why it would make a difference. I wish I would have kept him on the phone a bit longer to hear the reason for this but he seemed anxious to end the call.

Im wondering if I should even bother starting mine up..Maybe I should just send it in to them for the update..

Sure, send it in. Will probably get an even better idle. Also, don't forget to get that con rod replaced..[:@]

Steve..I just got the motor and the conn rod has been updated already...Im gonna just send it in..I cant fly for at least a few weeks anyway so Might as well get it done..

Hello everyone.
I am new in this forum (Actually this is my first post) and I just entered RCU to be able to post in this thread. I bought a DA 50 in May 2004 (first gas engine also). The serial # is 1477. My engine does not have the new rod or the new pressure line location.[]. Besides, I am in Colombia (south America) so sending the engine back in case something happens will be very difficult for me.[:@]
The engine have not been started yet so I will just go ahead and run it and hope for the best. In the meantime I have two questions:
The first one (Maybe RCIGN can help) is that according to what I have seen, the new pressure pulse line location is OK for solving the problem if the engine is inverted but it has to be in a different place if the engine is horizontal (mine will be). What I mean is that the fuel tend to puddle in the bottom of the carb block and this (where the fuel will puddle) changes if the engine is mounted inverted or horizontal. (I hope I explained this right)
The second question is: has anybody run many gallons through an engine with the old rod whithout any failure. I am sure engines previous to mine (#1477) don´t have the new rod and if someone has put one of these engines to serious work (300+ flights) whithout failure there is hope for me.
I thank everyone
Regards,
Andres

I would try it first just as it is, if you have the problem you can easily do the mod yourself...Take the carb and block off and look at the block..You will see the pulse hole in the block..Take a #29 drill and carefull drill from the outside of the block just deep enough to intersect the pulse hole..Tap the hole with an 8-32 tap..Unscrew the pressure tap from it's old location and plug the hole with a set screw..carefully screw the pressure tap into the new hole..Use some thread sealer to keep the tap from leaking...The wall thickness on the pressure tap is pretty thin, don't use much pressure when you screw it in..Connect the tap on the back of the carb to the fitting using the same hose, or if it's too short use a new one, length is not critical...You can rotate the carb if you want, it will make no difference where it goes...If you don't want to rotate the carb the shaft can be taken out and reversed...No rocket science needed here, just a little care...If the metal fitting on the back of the carb faces the wrong direction just twist it around, it's just a press fit in the hole...
If you happen strip the hole in the block some JB weld around it will work just fine, there's no heat there...[8D]

LOL!! You make it sound too easy!!

Or you can send it in. Retains your warranty. I have the same issue. Called today, it is going in tomorrow for the "fix". I personally would just rather send in in, let them do the work.

It will be nice to not have to worry about the motor quiting after a landing, or when I pick up the tail to roll it out to the runway.

Did they say how long it would take??

Been doing it for 18 years, to me It IS easy...If you live outside the US the shipping cost would be a good reason to try to do it yourself...DA knows not all users, many of whom can't or won't even try to adjust the needles, can't be trusted to drill and tap a carb block without screwing something up, so they will do it....The blocks originally were some kind of molded material and a little brittle, maybe they have changed to something better....[8D]

I'm sure there is a lot of DA's that have been run many hours without failure. I would guess the failure rate is dirrectly related to the type of flying. If your flying circles, loops, and not stressing the engine I'm sure it will be fine, However if your flying balls to the wall 3D, hovering and such with the old rod, your days are numbered. And so is your plane if it quites while your torque rolling 10 feet off the deck.

Here's what confuses me. DA could easily give a statement on this forum and clear up all the speculation. Other manufacturers do this. Take for instance Hitec. You can ask the factory rep anything you want on RCU. At the present time they are being pounded with questions about the 5955 Digital servo. It has problems, however Hitec is keeping people informed of the progress.

john

RCIGN Thanks a lot for your explanation in how to move the pressure tap location. I have installed pressure taps in glow engines before, so as you said it is not difficult and don´t think it will be a problem. However, I think I did not explained myself right in my question about the location of the pressure tap whether the engine is mounted vertical or horizontal. My guess is that the fuel tends to puddle in the bottom of the carb block because of gravity and DA is trying to avoid this by placing the pressure tap in there. Maybe the pressure pulse going trough the pressure tap will remove any fuel that migh accumulate there. If this is true, the bottom of the carb block (and therefore the pressure tab location) will be different in an engine that is mounted vertical compared to one that is mounted horizontal (90° apart). I hope you can get my point, Trying to explain something when English is not your first language can be hard sometimes... [&o] Anyway, If my guess is wrong would you explain me what difference does it make where the pressure tap is now in the DA 50 as where it was before?. I though that you can place the pressure tap in an engine anywhere as long as you get a good pulse?.
John, I agree with you 100% about DA letting everyone know what is going on with its engine (I guess that is difficult knowing that you have 2000 potencial problems (engines) out there). When I first saw this engine I knew I wanted one. I waited for more than one year to get one in order to have all the problems (new engines have) sorted out. I guess I didn´t wait enough.
I am sure for what I have read that DA will take care of all of us, unfortunately I am too far away and for me is going to be more difficult[]
I still would like to know about people that have put hundreds of flights on one of these engines with the old rod whithout failure. Maybe I will be one of the many lucky ones...
Andres

I can't see why it would make any difference where the tap is, but they must have tested it before moving....There is no outlet at the end of the pressure tap line, just a dead end in the carb body above the diaphragm...Unless there's a leak somewhere the pressure line should have no fuel in it at all. and it's a back and forth pulse anyway...More forth than back...

Ya know as I was packing up my engine to send in I got to thinkin...Is it necessary that they have the entire engine? Why couldnt we just sent the carb and the phenolic housing to them??..When they send it back they could send a plug for the existing tap..Has anyone that spoke to DA asked them this? If not I will call tomorrow and ask..If we dont have to why send the whole thing??

DA test runs all engines that are new and also those that have been repaired.