I have a DA-50 in a Yak. It is a newer engine, prob. has about 4 gallons of fuel through it. Using Lawn Boy Ashless 32:1. I am swinging a Mejzlik 23 x 8 right now.

The engine was sent back to DA before installed on this plane since there were some updates that needed to be done. This was in Sept.

So here is the scenerio. This engine runs awesome. I spent hours in the set-up, mainly working on the transition. It is perfect. No gurgling, popping, 4-stroking, etc. It doesn't matter if the plane is inverted, knife edge, etc. I have had many ask me to set their DA up as their's don't run as good as mine. So I feel lucky, and am truly happy.

The problem is........I can not get this engine to come down to a low idle instantly. It takes several seconds for it to idle down. I can have the engine idling at a low RPM on the ground. Run the engine up. Come back to idle and it will be a higher idle than where I initally started. It will stay at that idle for literally 8 - 10 seconds. Then it will come down to the low idle.

I have gotten use to this and have flown the plane more than 20 flights. But it really sucks coming in on landings especially and having to judge it like my turbines. I usually circle the field to allow it to idle down before entering my approach.

Any thoughts or other experiences with this problem?

Ryan

You are too lean on the low end and that prop is a bit too big to be using on the engine just yet. You should only switch to the 23 inch props after 5 or 6 gallons

I was really worried you were going to say that. I guess I have to decide what to do. It runs so perfect.....and transitions are awesome. I know if I richen it up it will idle no problem, but it will not transition as well and will "load-up" a little in certain manuvers. I have already been there with this engine during my set-up.

The 23 x 8 is too big? This is the prop DA sold me with the engine brand new. What should I be running?

Thanks for the info Bubbagates!

Ryan

Ryan,

Typically on a new DA50 you want a 22X8 like a NX, Mezjlik or PT model props or a Vess 22B or even the 22A. An MSC will not work as it is a wide blade and loads the engine too much.

During breakin you want the engine to burble a bit on the low end. At 5 gallons on both of mine I turned a 22x8 PT model CF prop at 7150 and at 7 galoons I could turn that same prop at 7300. I'm at 15 gallons and can turn a PT model 23x8 at 6800 and still be at 180 degrees.

Do you know what temps and rpm numbers you are at and the color of the plug.

Well.....hopefully I didn't mess anything up then. I am running the 23 x 8 which is what I was sold by DA when I bought the engine new. I have a 22 x 8 Menz standard here, should I use that now, or at this point, leave it alone?

In regards to RPM's, no, I don't have this info. I tached it when I first started, but I have not since it has been running so well. The prop tips are going super-sonic now. The plug color is good. It is a light brown to a greyish brown in color, if that makes sense.

Which oil are you running in yours at this point? Did you use Lawnboy Ashless and if so, when did you make the switch?

Thanks Bubba.....

Ryan

I agree with the low end being to lean and a 23-8 is too big for break in

I broke both my 50's in with a MSC 22-8. [8D]

Well shoot. I already have 4 gallons through it, guess it is back to the drawing board. I can't see how I messed anything up, unless a mess up equals a reliably running set-up. Any thoughts on what you would do now at this point?

Change the prop and re-adjust I assume..........

Ryan

It will be fine, just change the prop, very little agjustment if any will be needed.

Agreed, swap out the prop. richen the low end about 1/16th turn and go have tons of fun

These simple carbs are not gonna produce a best mixture thru the range on every engine they are fitted to
...some compromise is inevitable, you might have found the sweet spot for transition, but its obviously too lean on the bottom on this particular engine
swings and roundabouts


p.s., I know nothing about correct prop for da50 and assume the reccomendations above are correct, but overpropping is not the cause of the symptom you describe

I am with crusty,

Any hesitation to settle in idle qiuckly is sure sign of a lean idle mixture. Lean idle makes room for the possibility of engine cutting out without notice.
A smaller prop will worsen low load burble. I do not think a 23x8 twoblade small on any 50, as demonstrated by the prop ripping.
Low load burbling stems from two sources:
1) lack of scavenging gasses, which does not allow the spent gasses to be expelled sufficiently to fire on each cycle. This is the main burble cause. There is nothing that can be done about that. Going TOO LEAN will restore smoothness up to a point! Hey... it's a two stroke engine.
2) overly rich mixtures.

On some engines it is well possible to go too lean without the engine providing due feedback. Best idle setting is where the engine drops down slightly if the throttle is closed, and then ragains a few rpm.
Failure to settle down quickly is a sure sign of lean idle. This can be compensated for by making the load setting richer, but it is not the way to go.