When am I ever going to have a successful flight without my engine always quitting on me just when I'm starting to have fun? Almost every flight I have had for the last year, my engine has quit on almost every flight since then. I want to take my flying skills to the next level and take off from some where and follow my plane in my car. But I'm too afraid to do this because I know my engine will quit half way through resulting in disaster.

My last flight on my sig kadet lt-40 was over a month ago, I was having the usual trouble keeping my engine from crapping out in mid air. Everything was going good so far until it was time to land. My engine was idling to fast, even with the throttle closed, my plane would just zip by my field. I had my engine idling faster than normal because on the ground, when I would lower the idle, it would just quit. So I raised it a bit. When I figured the only way I'm going to get this plane down is to lower the idle so that its not coming in so hot. So that's what I did. Well on final, my engine quits and I'm heading for some wires. If it weren't for them in the way, I would have made my field. Trying to avoid the wires just made things worse. I ended up stalling the plane thinking I could go over the wires but instead, my wing clipped the wires, then clipped a nearby tree, then nose dived into the ground taking out my front fire wall and breaking off a piece of the front fuselage frame. Not too hard to repair with some epoxy and welbond, my plane should be ready for flight shortly. But is something going to break every time I go out to fly? I also tend to put off repairs, hence the over the month since I flew. I'm starting to think, whats the point of flying if this keeps happening?

One thing I haven't been able to do in a while is have a successful landing where I still have power. Nothing is more satisfying to me than that because its the hardest part of flying. I don't know why my engine keeps quitting all the time. Maybe its my lack of experience with these things. I have been only flying for 3 years but when it comes to engines, I'm still stumped. One thing I noticed after the crash was my clunk in the fuel tank was bent inwards toward the top making it so that no fuel could go in. This may have been the cause this time, but other times its something else and I intend to find out, otherwise I'm switching to electric where this won't happen that often.

I love flying this plane and have a blast when its not crashing. I just want my engine problems to be solved so that I can go out and fly my plane without knowing that my engine is going to give me trouble again. Every time I go flying, I say my engine is going to quit and it always does. I want to change this. Somebody please help. Its a O.S. LA-40 engine and its 3 years old. Some suspicions, I really don't know what I'm doing with this engine, but I see lots of air bubbles in the fuel line when the engine is running. Plus the clunk problem. I have an idle problem as well. I really don't know much about these little engines and when I'm about to fly, all I really know how to do is start the engine and fuel it up. I don't even really know how to set the correct mixture or anything else. All the help will be greatly appreciated. Please save my passion for RC flying.

Your best bet is to find a local hobbyist who can help you get started in the hobby. There are many tips and "tricks" of the trade that can make all of the difference

Where are you located.

Ditto. Get help if at all possible. Doesn't sound like it will take too long with an experienced pilot doing preflight and at your side while you fly.

You should take the tank out and pressure test it. You should then replace all the fuel line with new. See if this helps the "bubbles". the main needle valve has a "clicker" on it replace it with a small length of fuel hose that seals the needle valve and keeps it from moving due to vibration. the tubing should be large enough to slip over the needle valve and the needle valve seat.
The 40 LA has an air bleed type of slow speed adjustment. this relies on air coming in through a small hole on the front of the carb, and this hole must be clean. Take the carb off and clean it carefully. before removing the carb turn the slow speed needle in until it just seats and count the turns. after cleaning Set the main needle at 1.5 turns out, and the slow speed to the original setting.

Start the engine , set throttle at the top and adjust the main needle to max rpm, set throttle at idle or slightly above and pinch the main fuel hose hard and hold and see if the rpms go up or down. if rpms go up, too rich turn the slow needle out 1/4 turn, if down turn it in. Repeat the steps above until you get a clean low idle, clean transition to high, and the best top rpm. Slightly richen the main needle before flying.

Simple huh?

No offense meant but you should have a few seasons of flying under your belt before you jump into the back of a pickup and try cross country flying.

The final test you can make before taxiing out is to go to full throttle and hold the nose up. It should continue to run and not lose any rpm. If it quits, it's too lean. Best if you work the throttle and have your friend hold the nose up. This simulates the nose up plane in flight and checks to see if it will stall. Just my $.02.

I used to have the exact same problem you are having except I had an OS 40 FP and from what I can see from the LA engines there isn't too much difference except the color and the shape. I would fiddle with this stupid engine all day I would get it right on the idle but then it wouldn't stay there during the flight it would either idle too fast or die completely. I got so sick if this engine I took it off and deposited it in the dumpster and bought a OS 46 SF and a Super Tigre GS 40 best investment ever. I only have to set the high speed needles for the first flight of the day and never had to mess with the idle it used to suck having to fiddle with a sorry engine while your friends are flying around my advise look into another engine and save yourself some grief I ahve always had good luck with the OS SF's and Supertigres as far as 2 strokes go and I use Saitos for my 4 strokes, get engines with Ball Bearings those brass bushing are cheap and for a few dollars more you get more power. Another option fi you really don't want to get another engine that I have heard works is replace the stock carb with a Perry carb.

It looks like you got great replies fly with a buddy is the best
advice.one thing all my 2 strokes are converted to diesels which
if running and even badly adjusted will keep running of course
you want them adjusted as well as you can one of mine unloaded
in the air (running too lean) and was missing like hell which would stop a glow in a flash it knocked, missed maybe firing every
3rd or 4th stroke but it ran enough to turn it around and land
still running like chitty chitty bang bang

Sell it here or on E-Bay... easier than all the hassle-

The easiest engine I have had that is also light on the pocket-book is the TT Pro-46 ($80 bucks?)

Tune it and leave it-

Dual ball bearings, dual needles (easier and better than air-bleed) and more power than your LA-

Ok here is the checklist:
1. Make sure there are no leaks in your fuel tank. Take out the tank and watch for leaks or bubbles.
2. Make sure your clunk is not touching the backwall of the fuel tank. Clunk should always be 3-4mm short of the backwall of the fuel tank.
3. Replace the fuel lines with new lines. Bubbles means that your lines are leaking.
4. Make sure your fuel tank in not vibrating. Start your plane with the wing off and see how the fuel tank is behaving at different throttle settings. I had the same problem as yours. Turned out that the fuel tank was vibrating like hell causing uneven delivery of fuel.
5. Open the needle valve to a point where the engine is running very rich and then start adjusting from there. When you think you have set the needle valve properly raise your plane and if the engine speeds up you are fine if not you are lean. Richen up till you hear the engine pick up when you point the nose of the plane towards the sky.
. If after doing all this it still quits then you should switch to better Abc or Abn engines.

You could also drill out the air bleed hole slightly. Ive seen that work well sometimes on these types of engines.

I notice in a different thread that you asked the same questions 4 months ago, and got exactly the same answers that you got here. My question is did you try any of these suggestions over the last four months?

Here the original thread posted by Mr. Jorgensen: http://www.rcuniverse.com/showthread...552#post875400

the best response given 4 months ago came from Matt Kirsch:

SNIP

OS LA engines have airbleed carburetors. The adjustment of the low speed is very similar, except you turn the airbleed screw in the OPPOSITE direction you would turn a low speed mixture screw.

Airbleed carburetors control the idle mixture by regulating the amount of air that enters through that tiny hole in the front of the carburetor. The screw on the right side of the carbuertor is what controls the size of the opening.

Let the plane idle for a good 10-count, then quickly firewall the throttle. If the engine dies or hesitates, turn the airbleed screw IN 1/4 of a turn. If the engine blubbers and smokes, turn the airbleed screw OUT 1/4 of a turn. Airbleed screws are much less sensitive to adjustments than idle mixture screws, so you need to move them more to see any results.

While you may not get an airbleed carburetor to ever transition perfectly, you should be able to get a reasonable transition out of it. If you find that you have completely turned the airbleed screw out of the airbleed hole, and the plane still blubbers when you shove the throttle ahead, disassemble the carburetor and drill out the airbleed hole with the next size larger numbered drill bit. 1/64" or 1/32" of an inch may be too much, which is why you need the numbered drill bits.

END SNIPP

Yes, a very nice engine for the 80 bucks. Plus, I feel a perfect solution to all the "remote needle" hassles, just slant it away from the prop at an angle! I love my brand new TT Pro 46, and I haven't even started it yet! If everything on here is true, it should be a great little runner.

Wish I'd gotten to this thread sooner.

You don't need to sell that engine. There is nothing wrong with it. It's a perfectly fine engine that's user friendly and simple to use.

The problems you are having could happen to any engine, and they are twofold:

1. You have an AIR LEAK in your fuel system. There should be absolutely, positively no bubbles, period. The bubbles are keeping the engine from getting enough fuel, and it's dying from fuel starvation in the air.

2. You need to work on the tuning a little bit.

Remove and disassemble your fuel tank and lines. Throw away ALL the tubing. Make sure there are no sharp burrs on any of the nipples or brass tubes there may be in the fuel tank. Buy all new fuel tubing and reassemble the fuel tank. That should cure the problem.

Tuning the engine should be very simple with the airbleed carburetor. The airbleed adujstment has virtually no effect on the engine, and normally does not need to be adjusted. Simply set the top needle, and forget it. Tune the engine for peak RPM at full throttle, then back off 3-4 clicks. At full throttle, point the airplanes nose in the air and listen. If the engine speeds up a lot, it's too rich. You can close the needle valve 1 click and try again. If the engine sags, open the needle valve one click and try again.

You did get to it sooner, 4 months ago.

The plastic backplate on the la is a good place for a leak to occur.

ZB

Whille the LA is a good little engine, it does have its downfalls with the air bleed carb. Air temp will have a greater affect on these.
If you have the money get an OS 46sf or the TT pro 46. Have someon at the field help you. Also like the above pro's have stated, go through your fuel system.
I cant believe you dont have anyone else that can look at that LA. But it also depends on how you broke the engine in. If you've overheated it then there may be no hope for the motor.

Ok, here's an update on the status of my engine. I printed up all of the advice that was given to me and used it while I ran up my engine in my backyard. I think my mixture woes are finally solved. I did the pinch fuel line test and looked for the correct thing the engine should do when its at the right mixture. I pinched it for just a second and it sounded like it was suppose to. I believe an increase while being pinched, then when I let go the rpm goes down a bit but then returns to normal. So I think that's right I hope. I get a pretty clean transition from idle rpm to high and the engine seems to sound pretty good when it runs. Its not running rough or anything.

I checked my fuel lines for leaks and no problems there. Check my fuel tank, no problems there. Possibly a problem with the bubbles I was getting before was that the screw on top of the seal cap where the fuel lines go into the tank was not getting a good seal because the screw was not in enough. I tested it by blowing into the fuel lines and air would blow out from the cap rim. So I tightened it and no more air comes out. I get a good seal now. So hopefully my bubbles will stop now.

But now I have another problem that I can't really figure out. I can't seem to get my engine to idle right without it dying on me. What happens is when the throttle is set at idle (at the bottom) the engine idles right but it won't sustain the idle. After a few seconds, the rpm will decrease and the engine will start to blubber and then die right away. The only way to keep it from dying on me is to increase the idle but now its idling to fast and that's why I crashed last time was because I couldn't land because the engine was idling too fast, so I had to reduce it to the "right idle" but then it won't sustain it, it will just die. I tried adjusting it with the airbleed screw, but it doesn't seem to be helping. I have it screwed all the way out, which I was told was suppose to help it idle at a slower rpm but its not working so I'm thinking I may have to drill the hole bigger. Will this work? Exactly how much bigger do I make the hole? I don't know what exactely what the right idle should be, I just sorta know by sound because that is the only way I can really tell from before when I never had these probelms and my engine would idle and not die. I want it though so that when the stick is right at the bottom, it idles right and the engine won't quit but the only way it will stop is that if I bring the engine trim right to the bottom but I only have to have it half way for the engine to quit. This seems to be my only problem for now.

i don't think you need to be drillin on your carb. I have had several o.s. .40 la motors, and in my opinion they are an excellant little motor, for a good idle, make sure you have a GOOD glow plug. they do also like to have the air bleed screw set just right, the manual will give you step by step instructions on how to do this, and when making adjustments remember,,a little bit at a time. make sure your needle is set right ,,1 1/2 turns open from closed , then tune till peak rpm is reached, then back the needle off 20-30 degrees.

Get a 46fx, tt46, or just about any thing but the la, while some people have had good luck with them you will find many more that have had nothing but trouble with them, I had a 40 that ran fine for about 10 flights then it started loosing power in the air until it would die & I would have to land dead stick. I have a 2yr. old 46la on my son's trainer, it has about 30 flights on it with no trouble so far but I think trouble is right around the bend. In the future I will stay away from the la series engines.

Gil

I guess we all agree on this one I have their older (os) FP
which is a good running trouble free engine when the switch
to the new LA occured several years ago the proplems started
not knowing if rumor or fact a got a tt46 pro and 2 TT25 pros
which have davis diesel heads OS 10 also , by the way the little OS 10
was a problem till I switched to a FRONT carb.I know or at
least the sales pitch is rear mounted carbs safer I think we are
all careful on setting carbs . have been wacked a couple times
due to stupidity from the FRONT of engines, the tt has an
ANGLED back front carb an other plus

Get the TT Pro .46 and never look back. The LA engines are some of the most under powered engines I have ever seen. They also sound like they are going to come apart at idle they make so much noise. I go rid of mine as fast as possible. You will be amazed at the difference in power and smooth handling of the TT pro. You should check out National Hobby Supply for the TT Pro. I got mine there for 69.00. I do not know if the price is still the same but would be worth the look.

I will possibly look into getting a new engine, for now, can somebody help me on finding a way to keep my engine from stopping when its idleing? This seems to be my only problem for now, so before just tossing it away for another engine, I'm going to see what I can do with the engine I have now. I'm on a very tight budget, so buying a new engine would be my last resort if I were to fix everything, take it out to fly and find my engine still quits. I still have the option of taking it to somebody who really know's these engines. I just want to see if I can figure it out on my own as I am a little pressed for time to be going to the flying club. I usually fly solo at my own field.

Also, I'm getting a bit of vibrations in the front. I have always gotten a bit of vibrations, but the vibrations are enough to shake the fuel tank a bit. I'm really hopeing that the drive shaft to my engine isn't bent or anything from previous crashes.

Hello!
The OS LA engine you have is an excellent engine ( I have helped many newcomers in our club having this series of engine and all have worked perfectly from the start needing only slight idle adjustments.
The good thing for newcomers using this series of engines is that the carb with it's air-bleed function makes idle adjustments nearly unnecessary. Idle is nearly perfect from the start.... The idle function using the air-bleed screw is very marginal...so newcomers cannot really go wrong here.
But if you still can't make you engine behave properly you most have done something wrong!
Begin checking all the bolts on the engine. Also check the glow plug copper gasket...this gasket should not be reused when you take away the glow plug...always put a new copper gasket in whenever you change glow plug!

Fuel: Nearly every engine on the market runs better using some nitro....OS engines like 5-15% nitro ......more and you have too ad a (or more)0.1mm head-shim to reduce compression.
5% nitro is what I use in most of my engines.

Oil: Over here in Europe it is very popular to run 10-15% all synthetic oil like the French Motul "Micro" or the German Aerosynt 2 or Aerosave...but 20% castor oil is of course also working in your engine.

Glow plug: Always use a Enya 3 or OS 8 glowplug.
Propeller: If you fly at sea-level and it's a high-winged trainer you have ...use a 11x6 APC prop....10x6 will work too but the larger diameter of the 11" prop will give a more safer and lower idle (Idle should be around 2000rpm with the 11x6 APC).

Carb: The OS LA carbs have an air bleed screw that adjusts the incoming air through a small hole up at the front of the carb ..you should adjust the idle screw so that the hole is only slightly closed by the screw (look closely and you will see the screw treads inside the hole): most of the hole should be open....the screw should only be seen slightly when you look inside the hole. This idle function is not that sensitive and could for most of the time be left alone as it is......
No drilling up of the idle hole in the carb is necessary!!!
When you set the cab-drum opening it should be 1.5-2mm open in idle position
At this position the engine should idle at around 2000-2200rpm all day! and react instantly when you give full power.....

Fuel tank: It is of vital importance to most models that the fuel tank is not too large.....for a .40 -.46 engine a 8oz-10oz (240cc.300cc) fuel tank is perfect!
Larger tank ...and you might have slightly more problems adjusting the engine.
It is also very important that the tank is positioned so that it is close to the engine and mounted with lots of foam around it. Vibrations could other vise disturb fuel distribution.
The centre of the tank should be, with the airplane sitting level, inline with the fuel-inlet orrifice in the carb.....this is very important.
No air-bubbles should be seen in the fuel hose going from the tank to the carb when the engine runs.
Fuel hose should be made of silicon. 1,5-2mm in inner diameter....not larger!
And last....You have to listen and learn how your engine sounds when you do the tweaking on the carb main needle...this is how one sets an engine....by ear!

Hope you get your engine going.
Regards!
Jan K
Sweden

How many hours do you have on the engine? Could it possibly be getting worn out. The first thing to go is usually the idle on an worn engine. If you are having to keep the idle fast to keep the engine running it might need a new piston and sleeve. Also running the engine too lean can also cause it to wear out prematurely too. Something to think about.

Not sure how many hours the engine has. Its 3 years old and I have had about 30 or so flights on my plane in the last 3 years. I don't think its had so much time that its already wearing out. That's a pretty crappy engine to be already wearing out and I don't fly too often. Like only 10 times or so a year.

Unless you ran the engine lean it is probably not worn in only 30 flights. Here are a few things to check:

Fresh Fuel- I hope the fuel is not 3 years old too.

Good glow plug- Use the inexpensive OS A3 plug works great.

Check the setting of the low speed needle using the pinch method. Just pinch the fuel line going to the remote needle shut and see what happens. If it takes more than 4 to 5 seconds to start to die it is rich. If it immediately dies it is lean. Remember this engine has an air bleed adjustment for the carb and it works by letting in more air or less to set up the mixture at idle. Open to lean close to richen. Adjusting the low speed will affect the setting of the high speed needle but not the other way around. Also make sure you are adjusting the air bleed and not the idle stop screw which is on alot of these engines. I can not remember if the LA 40 has one. Also, I have always believed that using a 10x5 prop instead of a 10x6 would yield better climbing performance from this engine. A 11x4 would give the most thrust for a Fun Fly plane.