Holy cripes Batman,
I was following the other thread and figured it was just some wierd phenominon. Anyway, I got about 3 gallons through mine now and figured I'd start tweaking the needles a little. I was always rich on the low end so I went a little more then 1/8 turn in When Viola! I pick the tail up and it almost quits LOL.
Hey - I knew what it was right away!! I am going to richen it up 1/16 of a turn and see if it goes away. Mine doesn't quit, just bobbles really bad - only on the ground. The richness in transition is totally gone and I have good response. I figure I just went a tad to far on leaning the low end out. What do you guys think?
RickP

Same thing here. I lifted the tail and the engine would quit. I leaned it out to where it will drop in rpm when I pick up the tail but will continue to run. Put the tail down and run it up and transition is fine. Six flights of trial and error and I'm spinning a menz 24 x 8 at 6300 and idels at 1600 with real good transition. Whether lean or rich the time I spent to make it work is worth it. Very smooth running motor.

BG

BG,
I'm using a 23-10 Mejlik at 1700 idle. So you left it with a little bobble when you lift the tail? It also seems like the idle is allot lower in the air now. Exiting spins I can almost count the revolutions the prop is turning, If I bump up the idle then it won't sit still on the ground.
RickP

Try this experiment - BE CAREFUL!
with engine at an idle , have a friend help you carefully lift the model so that you can roll it -about 15 degrees to either wing.
see if this cleansup/prevents this funny bobble.
I ran into a similar thing on another brand reed valve engine.
the thing would rythmically surge at an idle .
by simply tilting the engine sideways a bit (fuel tank position is not related), the problem ceased.
This was an easily repeatable test so I got a chance to zero in on it.
Apparantly there was some puddling going on in th engine -very minor but it was there .
The cure in this case was to simply mount the engine tilted to about the 8:00 position.
It may not be true for the DA- but the test is easily done .

I've got a da 50 with just a tank thur it and it runs great. it idels at 2000 rpm and it does'nt pull the plane on the ground and top is 6800 rpm with a 22-8 menzS. both top and bottom are rich. I too was following the other thread and did the taxing around and stuff and never had a problem.

I just hope i dont have the same problems you guys are having.

P.S. guys from i hear this engine will run like crap till it's broken in and switched to syn.

Rick, I'm going to lean out the low end a bit more and see if I can bring the idle up that way versus the trim on the radio. Probably have better control/increments in adjusting it by the low end needle. You are right about the idle in flight. I might mix in the throttle down/up (100 rpm) for taxi and landing.

These are sweet engines from brand new to complete run in. Both have exhibited the same problems. One older version, got it last year and one this past April. I returned the older version to DA for their update crank and they replaced the crank and bearings for no charge. Not even shipping. The updated crank has no change to the problem, but does seem to be a little smoother.

I've read on a thread where the setting might change because the mixture screws back out because of vibration. So maybe it isn't a set and forget setting. Once I've got everything where it seems best I'll mark the mixture setting and see what happens.

I'm not a mechanic so this is all speculation on my part. Having fun though. Wouldn't trade it for the world.

BG

I've hear many fella's say that the problem will go away when going to synthetic...

I got my DA-50 back today after I had a hard landing (my fault) no dammage to the engine but I just wanted it checked.

They ran it and I guess tuned it to run right their at their shop.
I noticed it was a little rich on the bottom end so I tried shaking the plane lifting the tail up and I could make it quit by doing this.
I re-tuned the engine to run right at my altitude and temp (exc), now the engine runs like a champ.
The engine is still new and has about 4 tanks of fuel through it Lawn-Boy 32-1.
As far as I can see their is (no problem) with this engine except that you need to take your time and get the carb settings right.

As for going to the 100-1 Amsoil that makes sence that it helps because you are running alot leaner oil mixture and I wont load up as quick.

James

John,
Don't get me wrong, motor is rock solid - just bobbles a little when I lift the tail and the low end is too lean. Strange, Dicks comment makes sense except for the fact it only happens when it's too lean. I have no earthly idea what it's about - but I should be going to synthethic soon (hope this weekend) then we will know for sure
RickP

This problem (feature?) is not necessarily limited to reed valve engines nor is it limited to DA-50's. Both my Zenoahs, a G38 and a G26 (both converted to CH ignition) do it as well. We start smaller gas planes on stands at waist height (very convenient they are too.). You can warm them up and run them up, but when you lift the plane off the stand and tilt it to clear the restraints on the stand the engines bobble and slow down and sometimes quit. I solve the probelm with one click of throttle. Once on the ground they are fine and they cause no problems in the air. I have no idea as to the cause or the solution (there doesn't seem to be one). It just happens.