DLE 55 idle problem
 

I have 2 DLE 55's same prop, same gas mixture, same plug, both broken in. One is on a Yak, one is on an Extra. My problem is on the newest one has an idle problem. When adjusted on the ground I have good idle, good transition, good high end. When it comes time to land the engine has a very high idle. When I readjust the low speed needle the engine quits. Any ideas?

RE: DLE 55 idle problem
 

The low end needle sounds like it is too lean or you have an air leak in the carb block.
Im sure one of the others guys like TOM will Jody will chime in.

RE: DLE 55 idle problem
 

On the problem one, are you using Sullivan NyRod for throttle linkage?
Might be expanding from heat and altering the idle.

Go to a solid rod linkage with ball links and no more such issues.
Photo I'm posting is from a profile and has extremely short control rod, but gives ya the basic idea needed.
(note flat washer on each ball link, keeps them from coming apart {rarity})

-and/or-

Set your tx for two idles; one for ground running/landing (lower), another (higher) for airborne.

RE: DLE 55 idle problem
 

I would guess that the new one is still a bit tight and you are unable to adjust it low enough in idle so that when the load is removed on the prop it idles too fast.
It should be easier to adjust to a lower idle when it gets more time on it.

RE: DLE 55 idle problem
 

good observation, or its low end is too lean

RE: DLE 55 idle problem
 

Just to add to the thought process, it could be getting too hot. My other thought is the low end is maybe just a tick too lean. Before putting too much work into it, trying more difficult fixes, try backing the low speed mixture out one sixteenth of a turn and see if that makes it any better. The flying cylinder head temps can be recorded by purchasing a Venom Temp Monitor. They aren't very expensive and can tell you much about the temps you are running while flying.

,. http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXHUH3

RE: DLE 55 idle problem
 

Yet another thing to think about...if the idle mix is on the rich side....most engines will load-up and the RPM may drop enough to cause a engine to die ! Capt,n

RE: DLE 55 idle problem
 

Probably not.
Did you note this part?

RE: DLE 55 idle problem
 

You may have a good Idle....how about the engine???? I would like to read what he calls a good idle on thtat engine! Capt,n

RE: DLE 55 idle problem
 

If a 2-stroke engine is tough to adjust or the adjustments tend to drift, unstable idle, unprecise or drifting rpm as a function of throttle movement this usually is caused by too hot running temps. This can be caused by a too narrow exhaust or/and cooling issues due to insufficient or unproper baffeling.
But first of all, check throttle linkage and intake/carb sealings..first things first.

RE: DLE 55 idle problem
 

Thank you for all your responses. These are things I did before posting the query: adjusted the idle, set the airflow around the engine to about 1 to 3 (1 in to 3 out), changed plug.
These are things I did after the query: remove the carb, cleaned it, checked for any looseness, checked the coefficient of expansion between nylon and steel (even though my throttle linkage is a 4-40 rod) adjusted the idle.
This is what happened yesterday: dead stick.

I know this is an old thread, but I am having the exactly the same problem. Did you figure out what was causing this?

Post pictures of your installation. Did the engine work well and then develop the issue or has it had the issue from the beginning? What fuel/oil ratio? What brand oil? What octane is the gas? Have you checked the timing? What size prop?

Here is an article on adjusting Walbro carburetors. In addition to several other things, he mentions; 1) Dirt inside the housing; 2) Air leaks in the gaskets; 3) Extending the atmospheric pressure sensing aperture into the cabin; 4) Slight adjustment of the float needle arm.

Just yesterday I had a similar issue with a 50cc engine that turned out to be caused by dirt inside one of the chambers. I dissembled it at the field and blew out the passages with my hand pump, then reassembled and re-adjusted. Viola! Issue fixed. http://tech.flygsw.org/walbro_tuneup.htm

I hope this helps. :)

It's lean. Before getting too far into it just richen the low speed a hair. It's been my experience that this is a really common issue with any size 2 stroke. There's a VERY good chance it's not getting quite enough fuel from the idle system to cool the combustion chamber immediately when you bring it down after a flight. It'll cool eventually, but leaves you wondering from a second or 2 to maybe 10-15 seconds. Engines set this way will often quit unpredictably at low speeds as well.

99% of the time you can just richen the low speed needle a hair and it will reduce the or eliminate the idle hang issue, and eliminate the dead stick thing.

Bonus is it may be easier to start that way as well....

Richening the low needle did the trick! Thanks

Hello everyone.

sorry to drag an old post out of the closet but I have the same problem. Today I pulled my Great Planes 330s out to the field knowing I would have issues. I have been fighting this engine for a while. Finally got it somewhat tuned and then moved to NC where the weather has cooled. All my planes have needed adjustment, I knew this one wouldn't be an exception.

I tried to tune it with the cowl on and had issues seeing the screws so I took the cowl off, got it tuned perfectly on the ground, put the cowl back on an it was so rich in the air I had to land. Slowly leaned out the high end, taking it up each time, and got it to a small gurgle.

everytime I landed though, I literally had to drop the throttle trim like 10 clicks to be able to land. Let it sit about 10 min, try and start again, it won't start. Have to bump the throttle up....today was really not so cool that I think the engine is warming up.

I chasef needles all day...trying this and that. I have another 50 cc that I have been able to tune perfectly. I really think it is something outside of tuning bug I don't know what to check. It has a relatively new carb on it.

It it is a new engine but should have enough gas through it that I am passed the breakin period.

Pulling my my hair our, any advice welcomed, unless it is wrong :-)

If the engine won't settle down at idle, it's has a lean LS needle setting. One good way to determine if it is indeed lean at idle do this:

from idle, gun the throttle to full. If it stumbles and wants to quit, it is too lean. Richen LS 1/8 turn and try the idle test again. You are looking for a smooth transition to full. Once you achieve it, leave the LS alone for now and work on the HS. On the other hand if the engine burbles and doesn't transition smoothly but does eventually clear its throat, it's rich at idle. Lean only the width of a screwdriver blade at a time until transition is clean. This is where bench running is a good idea since everything is exposed. However I don't ever do break-in on the bench, only in the air.

The high end should be done with a tach such as a TNT. You want to get to max rpm at full throttle and then back off 100-200 or so. If any adjustments were required, check idle transition again. Do these tests with cowling off.

Assuming the engine gets into good tune with cowl off but changes with cowl on, there is likely too much pressure differential at the carb and you will probably need to run a fuel tube from the carb port into the fuse for equalization. Remove the 4 screws on the carb plate and silver solder a nipple or piece of brass tubing. Make sure the nipple or solder does not extend into the other side of the plate. Then just run a short length of fuel line into the plane, through the firewall.

Hope that helps

I am totally willing to try this but really dont want to do it with my current carb plate in case I screw up. Do you know any where the carb plate can be purchased seperately?

I also fear that if this is not the issue, I just add further unknowns to the scenario. Having one carb plate modded and one not would be useful.

Also something else I thought of. Yesterday, when I was having the problems, was the first time I ran the engine with an 1100 6.6 volt Life battery. I was under the impression that the DLE ignition could run with a Life battery. Could this have something to do with the drastic change I saw?

If the ignition module is a few years old and says 4.8-6V you'll want to regulate the voltage to the mid 5V range. That said, I don't think that's the problem here, but the higher voltage could shorten the modules life. Newer RcXcell ignitions are good for up to 8.4V.
A Tech_Aero IBEC will provide the regulation, eliminate the extra battery and add the safety and convienience of being able to control the ignition from the radio...OK, commercial over, back to our regularlry scedulal programming:o
Pete

If you modify the cover plate, you can still use it without the vent tube and it will work just the same as it always did before the modification. So you're out only your time if the vent tube doesn't resolve the problem.

I can almost guarantee 99+% that if the engine runs well with the cowl off then changes mixture settings with the cowl on, the problem is a pressure issue. You can also attack the problem by reworking the cowl to reduce the pressure changes. This is usually done by enlarging the exit area or improving the airflow through the cowl by creating a lower pressure area at the exit location.

Thinking the 55's came out after the switch to the higher voltage ign. modules, but that's still worth checking. Probably not related to your main issue though.

I'd pull the cowl again, and leave it off until you have it running right (based on test flight results). Then put it back on - and deal with any issues that show up at that point with the knowledge you are working with a cowling induced issue.

I think you were on the right track earlier (that the cooler weather may call for some tweaking), but assuming a ground tuned engine is going to run right once airborne is a bad plan. I generally suggest people not spend a lot of time getting that ground tune perfect for just that reason. Get it where you think it's going to be reliable (maybe just slightly rich as Matt suggests above) and fly it, keeping it over the field just in case! Then adjust as necessary, based on what it's doing in the air. -Al

My vote is for Truckracer on the need to enlarge the exit hole on the cowl to reduce the air pressure.

Thanks for all the advice. I pulled the cowl today on the bench, noticed the muffler gasket was bad and replaced it. Also got a new spark plug. Going to flight test this weekend with the cowl off and go from there. Will report back the results. I am usually pretty good and doing mods like the nipple added to the carb plate. Just makes me nervous that I don't have a backup if I screw up. If further tests show it is the cowl, I will either do the mod or change the cowl. I think the air movement if the cowl is prob pretty good though. Pics to follow.