Breaking in the DA50R
 

Hey Guys,

I am new to gassers, and want to know the correct break in procedure. The da50 manual seems a little vague. How much fuel should I run through it on the ground before flying the airplane. Also, the manual calls for a slightly rich mixture. Is this very rich like a glow 2 stroke or is this more of back off 500 rpm or so? Also, there are many recommendations on oils. If you have a favorite for break in, let me know. Any help would be greatly appreciated. Thanks.

RE: Breaking in the DA50R
 

Follow the manual. Use Lawnboy Ashless if you can find it (I get mine at Albertsons), mix 33:1, set needles so engine runs decent (don't peak it out and don't set blubbering rich) and fly it. Burn 6-10 gallons of break in gas/oil and switch to synthetic (I use Amsoil Saber mixed at 80:1, or 1.5oz per gallon). A gasoline engine is much more reliable during the run in process than a glow engine, so it's safe to fly it during that period. It is adviseable to adjust the idle a little higher while in the air though for extra measures. It is adviseable to fly it because that provides better cooling for the engine and it takes some time to get that fuel through it, so why not have fun doing it. As you run fuel through the engine, you can adjust the needles as necessary. Running a gasoline engine blubbering rich has an adverse effect on the engine, it should always be run reasonably close to optimum needle settings.
DKjens

RE: Breaking in the DA50R
 

Follow the manual. If you have any questions you can contact Desert Aircraft direct!


Thats the best way to do it.................

RE: Breaking in the DA50R
 

ZERO..just set the needles as mentioned above and fly..gassers need constant airflow to keep them cool so extended running on the ground will cause them to overheat..after 2-4 gallons of 32:1 then switch to any quality oil mixed at the correct ratio's and you are good..

RE: Breaking in the DA50R
 

Cool. I am liking these better than glow already. How can I tell where I need to be without peaking the engine? Also what did you mean by adjusting the idle in the air. Move the throttle trim up while flying? Sorry for the new bee questions.

RE: Breaking in the DA50R
 

You want to peak the high and low needles the same as you would your glow engines..back off the high a few hundred rpms for the first few gallons..set the low the same as your glow engines but stay on the fat side..After you start flying you will see if you need to lean or richen the needles. What I do is slowly lean the low end after each flight until it smooth's out..this can be a different setting from the ground tuning because as DK says, you will lean out a bit in the air so you want to start on the rich side..

RE: Breaking in the DA50R
 

That was very well said. Good lord, we don't see the forest because of the trees!
Tune it so it runs right, and fly it!:D

RE: Breaking in the DA50R
 

what servo should use on a da 100cc engine, thanks bomber

RE: Breaking in the DA50R
 

Another quick question. How do you peak a gasser. Do you tweak the needle valve with the engine running as usual"? Also, does everyone just setup the engine and then put the cowl on and fly? or is it popular like glow to drill holes in the cowl to work with the mixture. Thanks again.

RE: Breaking in the DA50R
 

They always run different with the cowl on. And then it runs different once you take off and start flying.

Tune it on the ground with the cowl ON. Go fly it and see how it sounds.

I tweak the needles with the engine running if I can. Not possible on some engines though because the carb is on the side and angled so the needles are facing the prop. I'm not about to stick my hand in there with a tiny screwdriver. Just shut it down and make a quick adjustment, then start it up again.

On your DA--adjust it running through a small hole in the cowl. Some guys have come up with very slick screwdrivers to slip through the cowl and adjust while it's running. A standard screwdriver is hard to keep from slipping off the mixture screws while it's runing and shaking. Guys will put a little piece of fuel tubing over the end of the needle and leave it hanging out a bit. Then, when you slip the screwdriver in there, the fuel tubing holds the screwdriver on the needle.

OR:
Some guys will cut the head off a popular size allen head bolt. (4-40 or 6-32) Remove the needles from the engine and have the allen head bolt brazed or welded onto the needle. Then you can use a long ball driver to make your adjustments.

Use a tach. Your new to this and if you don't have a good ear for tuning, you'll fight it forever. Lean the high side to peak and back it up a little. Then lean the low end and see how it keeps getting better and beter at transition. Eventually, you'll end up leaning the low end too far and it won't transition. Just back the low end screw out again so it transitions perfect. Now richen it up the thickness of the slot in the adjustment screw. That should knock your idle down about 200RPM. Go fly it for 5 gallons. You'll still have to make monir adjustments to the high speed needle on very cold days or very hot days, so don't get the idea your done adjusting needles. You DO have to tweak it sometimes. I check my engines every day. Adjust the high end once in the morning and then fly all day. Doesn't usually need adjustment, but I check it anyway. Most I've ever had to adjust it was about 1/16th turn.

Gas needles don't react to adjustments as quickly as a glow engine. On a glow engine every click of the needle gives an instant response. On a gas engine--better to make a small adjustment and wait 5 or 10 seconds for the settings to take effect.

Patience.

RE: Breaking in the DA50R
 

Yeow!! The needles on gassers are extremely sensitive to small movements. A 1/4 to 1/2 turn adjustment on a gasser can easily be equal to 1-1/2 turns on a glow. Go in 1/16 turn increments, wait, listen, and check before going father. Don't tune a cold engine, let it warm up a bit first.

RE: Breaking in the DA50R
 

I guess I didn't word that correctly.

The needles are VERY VERY sensitive to adjustments, but they don't REACT instantly. Make a tiny tiny adjustment and then WAIT for the engine to react. A little 1/16th turn lean on the high speed makes a HUGE difference.

I think this is where some of the guys get into trouble. They whack the needle valve and nothing happens instantly, so they whack it again. Engine quits. "My XXX won't run at high speed. Everytime I adjust the needles, nothing happens and then all of a sudden it just dies" :(

Gasser needles are EXTREMELY sensitive to adjustments--iin that a little bitty adjustment has a HUGE effect.

BUT--they don't REACT to those adjustments instantly. They take a few seconds to rev up or down when you turn the screws.


I make a tiny adjustment--never more than 1/8th turn at MAX--and then I listen to it and cycle the throttle a few times. Then make another very small adjustment and wait for the effect. Most of my adjustments are the thickness of the slot in the adjustment screw. Sometimes less. I just never notice an instant response from the engine. Mine always seam to take 5 or 10 seconds to respond.

For example:
If I need to lean the high end because I just bought a used engine from a guy at sea level, first thing I'll do is just start it. It' richer than Bill Gates at this point. I'll tach it and then shut it down. Usually only get about 5000RPM out of it with sea level needle settings.

I'll lean the high end 1/4 turn and start it. Tach it. Still rich.

Shut it down and lean the high end another 1/8th turn. Start it. Getting close now. Tach it. Usually, getting up in the 6500RPM range by now.

Put the tach away.

Now I lean it about 1/16th turn at a time and just listen to it. But, my adjustments take a little while to notice the effect. I've leaned a G-62 while it was running WFO (carb rotator block installed) and 1/8 turn adjustment took about 10 seconds for the engine to actually rev up and hold steady. Lean another little bit--thickness of the slot in the screw--takes another 10 seconds to rev up and hold steady.

RE: Breaking in the DA50R
 

What I go through to keep you out of trouble;)

RE: Breaking in the DA50R
 

B&B Specialties, has the perfect tool for adjusting the carburetors on everything but twins. BTW, I may be lucky? But except for the twins, that I own I have always adjusted the carb with the engine running, it's the only way to know if it's perfect, and with Dick's tool, it's easy and reasonably safe.

Dale

RE: Breaking in the DA50R
 

Alright, flown the DA50, starts right up great so far.

I am running the Pennzoil 2 stroke air cooled oil at a 32:1 ratio as per the instructions with a Bolly 22x10 Wood prop. The engine runs rich, the transition is pretty good and knock on wood, but no deadsticks yet. So far I am very happy with the engine. I have some questions though. I think I may be running a bit too rich as I am getting crap RPM's. Right now I am turnning about 6100-6200 on the 22x10. The transition is good, but the idle seems rich. The top end is rich and is sometimes missing every 5-10 seconds in the mid range. It clears up nicely at full power though. Also, is it normal for a gasser to drop below idle a little bit when going from wide open to idle? I have heard another gasser done this before and mine is doing this. These are the only two gassers I have ever seen run though.

All of your advice has helped quite a bit so far, but it seems that the needles aren't as sensitive as you were describing. I am probably too rich, but I wanted to know your thoughts. Thanks!