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?

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.

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.

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.

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

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.

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

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.

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

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.

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.

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

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.

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.

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.

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.

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.

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

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

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)

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

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.

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.

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

Nilo

Or, bum a cigarette from someone