Indiomike

My Feedback: (5)

I have a DLE 20, 30, and 55. The 30 and 55 run great. The 20 has been a headache. I've had it in two different planes and the problem is the same. The engine starts easily and transitions very nice to WOT. But after about 4 minutes or so in the air, the engine just quits. It can happen anywhere within the throttle range, high or low.

I've checked for air leaks, can't find any. I've tried two NGK CM6 plugs gapped at .024, still quits. I have checked carb screen, clean as a whistle. I've replaced the diaphram and carb gaskets, no difference. I'm running a fresh and tested 4.8v nicad pack for ignition power.

Now I have done three more things but I haven't ran the engine so I don't know if it has made a difference. I have installed a Frank Bowman ring. I have done the reed block modification Bowman recommends, and I have set the timing a bit closer to 28 degrees BTDC. I believe the factory setting is closer to 34 degrees. I should have checked the engine after each of these changes to see if one of them was the magic cure or not but I acted before thinking it through.

It will be a while before I can test the engine in the air as I don't have it in a plane at the moment. I can bench run it if need be. I thought the engine may have been run too lean but I adjusted the HSN so that it ran about 300 rpm below peak. That did not solve the problem. Also the plug did not show a lean coloration.

I had sent w8ye a PM and he suggested I share this on a thread and so here it is. About the only things left to do that I haven't done is change the ignition module and/or change the carb with a new one.

Any other thoughts?

Mike

ahicks

My Feedback: (2)

Geez, you have the other ign. modules/components that will plug right in, that would be on my list of things to try early on! Is this the same battery you've been using right along, or have you tried swapping that out (regardless of voltage reading)?

The 4 minute thing is when it's in the air only, right? You are not able to duplicate that on the ground?

Cooling? What are you running this on? What does the cooling air outlet look like?

pe reivers

Small engines are quite content with 20° to 24° ignition advance. Did you try that?
Second idea is that the ignition module gets hot. Give it some fresh air to operate in.

mpascual

My Feedback: (1)

+1
I'v found the same as pe, about advance angle.
Try pe's suggestion .

Best regards

Checklst

+2 electronics can get a little strange as they approch hot...........

Indiomike

My Feedback: (5)

Thank you for the replies. The engine was first ran in a OMP Fusion profile which is of course no cowl whatsoever. Both engine and ignition module was out in the open. The second model was a Seagull Yak which was fully cowled. The engine could be started easily and probably run for about 2 minutes before takeoff. So total run time before engine quit is about 5 to 6 minutes.

Al, both planes used different ignition packs but both were 4 cell 4.8v nicad packs. I can substitute the ignition module with another but it wouldn't be the #4 that comes with a DLE 20. I am leaning toward an ignition problem more than anything else at this time. Something is occurring around the 5 to 6 minute mark once the engine starts. One thing I haven't done is run it for 6 minutes or so on the ground to see if it quits. It has always occurred in the air.

Looks like I have some more testing to do. W8ye suggested the #4 ignition module may not work well with the timing reduced from the factory setting since it has a special curve that may work best at about 34 degrees BTDC. If I can get the engine to stay running with a standard RCEXL ignition and with the timing close to 28 degrees I'll be a happy camper.

Mike

pe reivers

It is not the ignition that runs best. It is engine ignition timing that should be considered. The ignition advance curve plays a minor role at intermediate rpm. Unless the advance curve is waaaay off like in the #4. For top rpm it is the max advance only that counts.
PS
My 50cc racer had it's ignition timing set at 0.9mm BTDC, that is 18 - 20° advance for tuned pipe use. No more! (motoplat, breaker points initiated)
It ran up to 16,000 rpm without problems.

johnfly

I don't think it is the ignition module heating up.... i have a dle 20 in a ultimate where the module is wrapped in foam and stuffed in the nose behind the firewall..... very little airflow there but i have never had a problem with the motor diying !!! I run the ignition on a 2cell life pack with castle reg. set to 5.1 volts.

ahicks

My Feedback: (2)

Mike, the number 4 just has a different curve (or probably better described as a "step") than the other modules you have? Mid and top end (anything over 3000 or so) would be identical one vs. the other. Replacing it with one of the others for testing purposes won't hurt a thing. Would be a totally legitimate test.

Could it be related to the fuel level in the tank? Same tank used on both installs?

For the life of me, I can't figure how timing that was off, or reed valves not seating properly, would cause a running engine to QUIT. If not running/starting properly, OK. But not just quitting completely....

Purely out of curiosity, what happened to the Fusion? Why did you pull the engine from that? -Al

SpinnerRow

Could it be overheating?

Indiomike

My Feedback: (5)

Al, two different tanks used. I'm not sure fuel level is that critical when Walbro type carbs are being used as opposed to glow engines. Some of the things I've done I'm sure will not have any bearing on the engine quitting. I don't think switching out the ring to a Bowman ring has anything to do with it quitting but I simply wanted to use one of his rings. Same for the reed block. My state of mind is that I'm going to change out every single component on this engine until it does run right. If nothing else, it will be a good learning experience with gas engines. I also have a complete replacement carb to try and new ignition module, although it is not a #4.

Oh, the Fusion. The engine quit when I was too far and too low to get back to the runway. Where I fly, it's all scrub brush and rocks (big boulders) off the runway. The poor Fusion must have hit every damn one LOL.

Mike

Indiomike

My Feedback: (5)

SpinnerRow, I don't think so for 3 reasons. The engine was quitting when it was installed on the OMP Fusion which is a profile type plane and there is no cowl. Air cooling is at the max. The engine was tuned to about 300 rpm below peak which puts it on the slightly rich side. And finally, the plug color was not grey or whitish looking which would be an indicator of a a lean condition thus prone to overheating.

As for an air leak, I've checked every bolt on the engine to make sure all were tight. One thing I haven't tried is spraying carb cleaner all around the engine and carb to see if it causes the engine to quit. I have read that is a way to test for air leaks but I have never tried it myself. I don't know if that is a reliable test or not.

I'll find the problem if I have to replace every single item on or within that engine. I'm just stubborn enough to do so. LOL.

Mike

3136

If you crashed it in a previous airframe I would be very suspicious of the plug boot.
Try your other ignition before you do anything else.

Indiomike

My Feedback: (5)

3136. Yes, I already did that. There was a dent in the boot so I ordered the replacement kit from Valley View RC. A simple procedure and necessary to insure integrity. However, I will give the engine a good 10 minute run using a replacement ignition module. I'll change throttle settings simulating normal changes I would make in the air. This engine is not installed in a plane at this time.

Mike

ahicks

My Feedback: (2)

Love the attitude Mike. That's what it takes some times....

You'll get it!

I was thinking maybe the fuel level in the tank was drawing down to the point you started sucking air - like when the pick up tube comes off?

unclecrash

One thing I haven't tried is spraying carb cleaner all around the engine and carb to see if it causes the engine to quit.

This would be a good thing to do you could have a hair line crack anywhere. Also the engine will not quit when spraying it down you will hear the engine pickup rpm if there is a leak. At least that has been my experience when trouble shooting an engine for a leak.

Indiomike

My Feedback: (5)

Well, I believe I have solved the problem with my DLE20. Since it had last ran, I did three things to it. I put in a Bowman ring, did the reed block mod, and changed the timing to about 28 degrees BTDC.

So I put the engine on a test stand and tried to start it. Nothing. Couldn't even get a pop out of it. Tried a brand new #4 ignition module from a new DLE20 I had on hand. Still no go. I swapped out the carb off the new DLE20 to the engine. Still nothing.

I was just at about a complete loss as to what the problem was when my eye focussed on the ignition sensor wire. So I took it off and put on the one from the new DLE20.

VARRROOOOM....Dang engine fired right up. I put the old carb back on along with the old ignition module, and reset the timing back to 34 degrees but kept the new sensor on. Engine fired and ran.

So it appears the problem was a bad connection, possibly a broken wire within the hall sensor ignition wire. Engine ran for a good 25 minutes without quitting at any throttle setting. I had a fan blowing extra air on the engine during the run.

Problem solved. Case closed.

Mike

ggraham500

My Feedback: (4)

Good for you. It usually is something very basic.

av8tor1977

My Feedback: (6)

I've had this happen with sensors before. Usually they are either "go" or "no go", but every once and a while one will go "whacky" and do strange things. Bill at CH ignitions confirmed this with me one time a while back.

AV8TOR

Steve

My Feedback: (54)

I'd put your timing back to 28* BTDC and see how you like it.

plaurence

My Feedback: (2)

Got my first gasser, DLE 20.

How does one change the timing?

w8ye

My Feedback: (16)

There should not be any need to change the timing???

Indiomike

My Feedback: (5)

The hall sensor is attached to the prop hub by 2 screws. If you loosen them the sensor can be moved left or right. Notice the prop hub has a round magnet embedded in it. It passes underneath the hall sensor. When the piston is at top dead center the distance between the magnet and the sensor is what the timing is. You change the timing by moving the sensor either closer or farther away from the magnet. I think the DLE 20 is set at about 34 degrees from the factory but a lot of guys say that the engine will run best at about 28 degrees. It is possible that the 34 degree setting is used specifically for the #4 ignition module that comes with a DLE 20. The #4 module has a different advance curve than the standard RCEXL module which seems to work best at the 28 degree timing.

To do a timing change properly, you need to use a degree wheel. There is a YouTube video that shows this but I don't have the link for it. Maybe someone else can provide that.
Mike

plaurence

My Feedback: (2)

Mike,
Thanks for answering the question .

Pete

ahicks

My Feedback: (2)

Nice going Mike. I knew you'd find it eventually....

It's always the simple stuff that seems to kick your butt the worst? (Aww, there's no way that sensor is bad....)