Engine trouble
 

I have an alpha trainer and I'm having trouble with the engine. When I get it started it runs very rich. When I give it throttle it starts to spool up and lots of fuel comes out of the exhaust. I have taken off the needle stops and have adjusted to every extreme and fuel is still coming out of the exhaust soaking the ground. I took the tank out and checked the lines and cant find any air leaks. Any suggestions on what to check next?

RE: Engine trouble
 

You can bypass the stop and lean it out but what I have seen that most of them do this when new. Maybe let it break in a little on the rich side and see what happens later. SO long as the engine does not die, you should be OK.

RE: Engine trouble
 

Some fuel coming out of the exhaust is normal for a 2 stroke especially when you first start it . Are you sure that you are not over filling the tank and fuel is running out the presser line or you could just be over priming . Be sure that it is fuel and not oil the oil is normal that is how a 2 stroke cools it self.

RE: Engine trouble
 

Air leaks in the fuel lines and tank make the engine run lean... not rich.

You already pulled off the needle limiter... pull the needle and look at it. I had one needle valve that came from the factory with the actual needle portion missing. (should taper down to appx 1/128 inch dia at the tip. If it ends abruptly after the threads you found the problem.) Its a rare problem... but its happened before.

The engine is supposed to spit a fair amount of goo out the exhaust. Thats the unburned oil. The fuel has appx 16% to 20% oil by volumn. 90% of the oil does not get burned.

RE: Engine trouble
 

Look down the carb throat and see if the spraybar is in alighnment...check low end adjustment.

RE: Engine trouble
 

I appreciate your replies. The amount of fuel that is coming out is way more than normal. I have taken out both high and low end needles, both seem to be ok, not exactly sure what to look for.

Troll, not sure what the spraybar is. Is that the bar that the needle seats in inside the carb? If so I watched it go in when i put the needle back in.

I was thinking it was an air leak since it was running fine and then just went bad. I have checked both lines from the tank as well as the rubber o-ring around the tank, everything seems fine.

The plane is about a year old and ran fine before so I think its broken in.

RE: Engine trouble
 

Perhaps a chunk of debris has found it's way into the NV seat, so when you turn the needle in, it doesn't shut the flow down. Has anyone ever closed the NV all the way, (perhaps a bit too tight?) This would damage the needle seat, and cause the problem you are describing. Here's the fix, or at least a test: Put a wheel collar on the fuel line between the tank and carb. Once you get her fired up, slowly close the allen screw of the wheel collar down, 'til you are squeezing off the fuel line. it should lean out- if you have a damaged seat, or debris.
I've run planes with this sort of a "field fix" for the season, no problems
If you have debris suspected, use a fuel bulb, sqeeze it, attatch it to the carb nipple then release it, sqeeze it out on a paper towel, or other white paper to check for crud, repeat, this may clear out the seat.
Hope this helps,

Jetts

RE: Engine trouble
 

Juice, is this the Evolution Trainer Power system?

If so, close the low end adjustment, then open it 1 1/5 (One and one fifths) turns. Check the needle as mentioned, and try again.

RE: Engine trouble
 

I just saw Fhuber comment about the shape the needle should have and I guess I have this problem.
My evo46 is still driving me crazy, even after I sent and received it back from Horizon where they said they replaced the carb.
The engine looks also running rich, bad transition from idle to high speed and the worst of all, very randon behavior.
I adjust the idle needle for a good idle and transition and high speed needle for good high and when I stop at the runway to take off, it just don't respond from idle to high anymore![:@]
I saw that by looking inside the carb when it is fully open, the needle that is the left part and that moves in and out of a hole in the right part ends abruptly.
See picture below and let me know if I'm in trouble!

Nilo

RE: Engine trouble
 

Nilo,
No, you're fine in that department, the needle he is talking about is the "remote" one, the highspeed needle. A squared off low speed screw is fairly normal. In your case, I highly recommend you find someone near you who has good running engines and get them to help you. It's hard to troubleshoot engine problems on foums like this.

Juice,
If the engine ran fine, then started going rich, something changed to cause it, and the question becomes "what changed". Did you switch to a new brand of plug or fuel etc? Different fuel tank or plane? new prop? anything.

If you take the limiters off, you should be able to adjust the low and high speed settings more to the lean side, enough to get the engine to go past peak and not run well. Start up the engine, and go to full power, then lean the engine out until it goes past peak rpm and slows down. Then back it back out and set normally. This will tell you if the high speed needle is working or not. If you get all the way to the stop, and it still is running rich, then Jetts is likely right, something is holding the needle open. If the high speed can be adjusted from too right to too lean, do the same thing at idle, using the low speed screw. You can turn that quite a ways in before it stops turning. If you moved it all way in, and still the engine is rich, something is really off in your carb. Depending on the carb design, I can think of a few possiblities, but I don't want to go in to them, as I don't recall the Evo's carb well enough to say which apply to that carb and which don't.

RE: Engine trouble
 

Great info jettstarblue and Montague, I'll try those out tomorrow.

I can tell u when I squeaze the fule line it does lean out and start to accelerate but when I let go its goes back to rich. It might also be possible that the low end needle was damaged I have turned it so many times who knows.

RE: Engine trouble
 

The Juice,
If you can't get it going right, let me know, you can send the carb to me, and I'll either fix it, or send you one of the ones I have.

Jetts

RE: Engine trouble
 

Juice, did you try what I suggested in my last post? That is the instructions I got from the Manufacturer when I had a similar problem.

RE: Engine trouble
 

Btw, I don't know if you said if you took the low speed screw out, and I don't know if it applies to your carb, but here's something to look for. On my Magnum carbs, the low speed needle is a long, thin rod that has to go in to a small hole when installed. It's possible to put it in out of alignment, so it misses the hole in the end of the spraybar. When you do this, it's like not having a low speed needle at all, and everything goes really rich and runs poorly. Usually you can see if this is the case by looking down the carb throat and making sure everything is lined up right.

RE: Engine trouble
 

Minnflyer,

Yes it is the evolution and i did try the that needle adjustment. If it stops raining I'm gonna go try all these recommendations.

RE: Engine trouble
 

Well I have tried and tried and still too rich. I was looking at the low end needle again and was wondering how pointy it should be? It is somewhat flat at the very point, it does seem to seat fine though when i screw it in. The engine seemed to run better when I had the low end almost completely shut. I was thinking of replacing the low end needle, maybe it got flattened.

I tried sucking and blowing through the carb to clean anything out and that didnt help.

RE: Engine trouble
 

Here is what you should do...

First, make sure that the low end needle is one and one fiths turn open, then, go to the field and have an experienced engine guy run it.

If he can't get it running right for you, call the Manufacturer. Evo has great customer service, and will fix it right away, or send you a new engine.

RE: Engine trouble
 

i would also try looking at the muffler befell inside if its cracked or a Peace missing itl put to mutch presher in the tank

RE: Engine trouble
 

Mike,

I found that there maybe mistakes on the reference to use when adjusting the 1 1/5 turns on the idle needle.
If the carb is closed completly or open 1mm as the manual suggest for idle point, there will be quite diference on the 1 1/5 turn adjust.
Which is the carb position when adjusting the 1 1/5 turns, fully closed or the idle position?

Also, someone in the field told me last time to fully open the carb and look at the needle inside. The start point for the neddle adjust shoud be when you see a very small gap between the needle and the hole where it fits in. Is this something also ok?

Thanks,

Nilo

RE: Engine trouble
 

The low end adjustment turns with the barrel, so it doesn't matter what position the carb is in.

Also, when mine is wide open, I can see no gap between the bar and the needle.

For what it's worth, I'm posting this pic just to be sure that everyone is adjusting the correct screw (Many people turn the wrong one)

RE: Engine trouble
 

Mike,

Yes,the needle turns with the barrel, but the bar doesn't turn, so when the barrel turns, the needle also turns and get more or less inside bar(where the fuel comes from) to allow more or less fuel to come out for proper mixture air-fuel.
If I close the needle when the barrel is completely closed and go back 1 1/5 turns, it will be in a diferent position than I do the same when the barrel is not completely closed.
Yes, I agree that after you setup the start position, it doesn't make diference what the barrel position is, but for the 1 1/5 turns to total closed, it does. If you close the needle totaly with barrel fully closed and then open the barrel 10%, the needle will not be closed anymore, but 10% open.

I'm still wondering what the barrel position should be for the 1 1/5 reference.


Nilo

RE: Engine trouble
 

I was told b4 u make adjustments your throttle and trim should be completely closed.

Mines getting closer but still not working right. I'm losing top end as the bottom end is getting better. I have the bottom so far closed that even with the trim all the way up it wont idle, it has to have some throttle.

RE: Engine trouble
 

Nilo, my mistake, you are correct.

Juice, Remove the blue collar from the low end needle. Then, close the throttle so that the opening in the barrel is only 1 millimeter (For reference, if you look at the white paper of a cigarette, they have grey lines that run around the outside diameter. Those lines are 1 mm apart from each other)

Now, with the throttle open 1mm, close the low end needle, and re-open it one and one fifth turns.

Then, reinstall the collar.

Next, start the engine, and get the high end adjusted with the high end needle. At that point, the engine SHOULD be performing properly. If not, it's time to contact the MFGer.

RE: Engine trouble
 

If you're not a smoker, 1mm=0.04"= little less than 3/64" = little thinner than a penny.

Nilo

RE: Engine trouble
 

Or, bum a cigarette from someone :D

RE: Engine trouble
 

Well I was able to get it flying long enough for me to solo today. It is still running rich and the low end is pretty much closed. After flying for a couple of minutes it seems to lean out a little though. I cant understand it. Someone mentioned there might be some o rings inside the carb to look at for air leak. Anyone know what they are talking about. Another person mentioned that the prop might not be balanced and is causing air bubbles. Any suggestions for checking balance?

RE: Engine trouble
 

Air Bubbles would cause it to run Lean, not rich.

BTW, are you using the 3-blade prop that came with it? If not what size prop are you using?

If you like, you could send it to me and I'll send it back either in ready-to-run condition, or with a recommendation to return it to the MFG. (No charge - not even my shipping cost)

RE: Engine trouble
 

I'm using a 2 blade, 10x6. Thats a generous offer minnflyer hopefully I dont have to go that far though.

RE: Engine trouble
 

Ok, I just wanted to be sure that it wasn't too big, but that should be fine.

RE: Engine trouble
 

Mike, remember my evo 46? Sent to repair and was still bad!
I gave up! Packed and left in the retail store for then to decide what to do with it. Fix it or throw it away! I preffer the money back!
Will go by OS or Magnum to replace it, what you guys think is the best bet?

Thanks,

Nilo

RE: Engine trouble
 

Given a choice between those two, I'd go OS

RE: Engine trouble
 

Nilo,
I suspect your problem is your lack of experience in tuning your glow engines. I have broken in several EVOs for newbies at the club and was impressed by how well they ran. Each evo engine is run and carb limiters set prior to sale.

Here is a how to engine tuning guide I posted on another rc website. Before you attempt this, remove all of the stops/limiters on both the low end and high end needles

Too often, I see newcomers to our hobby ask online how many turns do I set my needle valves, or I messed up the factory setting, how do I setup my low end needle so I can start my engine? Here are some great tips to make you an expert engine tuner.

How to setup the needles so you can get your engine started:

Start by opening the high end needle about 4 turns from fully closed. This is just a starting point to ensure the high end needle valve isn't restricting fuel to the carb so you can adjust the low end needle setting.

The low end is easily set to a good starting point with the following procedure:

Close low end needle valve completely.

Install a clean piece of fuel tubing into carb fitting, make sure it is long enough for you to blow into it with your mouth.

Open carb to 1/5 open from closed position

Blow into fuel tubing while slowly opening up the low end needle valve. Stop turning low needle valve when you first feel air blowing into carb from your mouth or hear the sound of air blowing into carb. The flow should be restrictive and very small. We only want a small amount of fuel to flow (air to flow) at 1/5 throttle opening. This low end needle setting will get your engine running and may require further adjustment. THis is just a ball park setting.

Now close high end needle valve and open carb to full throttle. Blow in fuel tubing and simulataneously open high end needle until you have FREE FLOW of air into carb. You should not experience as much resistance to airpressure as you did on the low end. Your needle valve should be open between 2-5 turns (it all depends on the carb folks).

This procedure gurantees you don't have a blocked carb or closed needle settings for low and high. This will get you in the ballpark which then will require you to fine tune your low end and high end for best performance--highly recommend the pinch test .

Pinch test procedure:

First start engine this way:
Prime engine by opening up throttle to full and blocking exhaust with finger. With blocked exhaust, rotate engine until fuel just enter's the carb-watch fuel line to see fuel displacing the air in the fuel line.

Remember the following rules about needles:

1. Low end needle affects the mixture below 1/2 throttle for most engines. Use it to adjust the idle and the transition from idle to full throtttle.
2. High end needle affects mixture above 1/2 throttle. Adjust it so engine is running 300-400 rpm shy of max lean rpm at wide open throttle.


Reduce throttle from full to about 1/5 throttle opening. Apply glow ignitor and rotate engine (hopefully w/ starter) counterclockwise (for 99% of all engines out there) until engine starts. When engine starts, move throttle to 1/2 throttle and then remove glow driver.

If engine won't start, try more throttle until it does. If engine will only start above 1/2 throttle, it means your initial low end needle setting was too lean. Richen it about an 1/8th of a turn until the engine starts at a low throttle (1/5 throttle) setting.


If engine will not advance to 1/2 throttle w/ glow driver is on then leave at 1/5 throttle with glow driver until engine is warmed up-about 2 minutes should do the trick.

Advance throttle again to 1/2 throttle slowly. If engine dies then your low end needle is probabably too lean. Richen by 1/10 increments.

Once you can get your engine running at 1/2 throttle then its time to remove the glow driver/ignitor. With ignitor removed, advance throttle to full throttle. Chances are your engine will be too rich and may even quit. If so, briefly pinch and release fuel line as you advance to full throttle to verify the mixture is too rich. If it is too rich, then in small increments lean it out until it will run at full throttle without quitting. This does not mean the high end mixture needle is set. This is just a starting point to ensure your engine is running at wide open throttle (WOT) so you can make the proper adjustments.

With engine running at full throttle, slowly and carefully lean the high end needle valve until the engine is spinning at its max rpm. This can easily be determined by sound alone-no tach needed. This is where engine is producing most power but the mixture setting will cause the engine to run too hot and overheat. So, as a safety feature, always richen the mixture about 300 rpm shy of max lean rpm. Verify this by briefly pinching and releasing the fuel line to the carb. If the pinch test causes the engine to speed up and back down, then you have correctly set your high end needle setting. If engine doesn't speed up much or dies then you are still to lean and need to riche the mixture slightly until it passes the pinch test.

You are almost there. With high end needle setting set about 300 rpm rich of max lean rpm, recheck idle and transition. Let engine idle for 30-60 seconds and then snap throttle to WOT. If engine hestitates in the transition, fine tune mixture so that the transition is snappy and idle is reliable. I personally like a lean idle mixture so I can idle for long periods without fuel pooling up in the crankcase which causes stumbles when transitioning to full throtttle. You can also use the pinch test when the engine is idleing. Pinch and hold fuel line with engine at a fast idle. Engine should speed up and die about 4 seconds. If it takes longer, your low end needle is too rich, if it takes less time or if your engine dies instantly, you are to lean and need to richen your low end needle.

Once low end needle is set, you will probably never have to adjust it again. However, your high end needle should be checked before every flight by doing the pinch test at WOT to verify the mixture is slightly rich. This 5 second test and adjustment, if necessary, will gurantee you a reliablie engine that will last a long time. Our carbs do not adjust for changes in temperature, humidity, barometric pressure, etc... and a small change of 5 degrees in temp can cause a properly tuned carb to be out of tune and possibly too lean (or too rich depending on whether it gets hot or cold outside).

Hope this essay helps the newcomers to our hobby and prevents them from becoming one of the set it and forget it crowds that do not benefit from optimum tuning for the best engine performance and longevity out of an engine.

RE: RE: Engine trouble
 

Homebrewer, that's a good user manual you post here!

I really thank you, but this engine came with many problems from factory, like I said, cracked fuel line from needle and carb, bad carb (Horizon replaced it), piston getting stocked.
I can say that pretty much I did try if not all of then, most of the techniques to tune this engine you discribed, double and triple checked all external things like fuel lines, tank, so on.
At this point, I'm considerin two things. The first and what I prefer is getting my money back and buy an OS engine. Second, if the retail store fix the engine, I'll probably have to accept it back, but will take time for me to trust on it.

The worst part is not being able to fly. I'm thinking about buying the OS engine even before getting this issue resolved. My flying adiction is killing me!:D

Nilo

RE: Engine trouble
 

OS. im only on my third plane but all have os and i havent had a problem. youll pay a little more but it is definatly worth the bs youre dealing with. my .46 ax&fx can transition fairly nice and i can set the throttle so low that i can see the prop spin(slightly exagerated).go with the os and you wont regret spending another 20-30 bucks.