Difficulty Tuning an Evolution Engine
 

I am having problems tuning the [link=http://www.horizonhobby.com/Products/Default.aspx?ProdID=EVOE100]Evolution Trainer Power System [/link] engine in my Alpha 40 trainer. The trainer was crashed and I rebuilt it. There was enough of an impact to break the High Speed Needle Valve (HSNV) off of the engine. I replaced the tank, fuel lines, high speed needle valve, glow plug, and prop. I wanted to get her in the air to see how the rebuild went, and she flew fine at WOT for several minutes. Throttling down to land ended up with a dead stick landing because of an engine out.

I replaced the glow plug again (first replacment was a used one, this one is new) and have new fuel in her, but she does not stay running. She starts just fine but throttling up quickly causes it to die unless I go to idle. (Sometimes it stays running, but sometimes it does not.)

I can sometimes SLOWLY advance to full and I can adjust the HSNV but it may run like that for a bit then die. She idles fine. I tried pinching the fuel tube while at WOT and she drops RPM and dies so I richened her out and this was fine for awhile.

The HSNV is brand new so maybe the limits are set wrong? I wanted to ask before I did anything.

I am at the point where I am ready to send the engine in for diagnostics but did not know where or how much that would cost. A new one is about $80 so would it even be worth repairing by the time I pay round trip shipping, diagnostics, parts/labor, etc? I know you cannot answer that because you do not know what the problem would be but I am thinking on the low end it would be about $25.

Thanks.

RE: Difficulty Tuning an Evolution Engine
 

Remove the needle valve limiters. They will get you close but for precise tuning you need to remove them. If it spits and sputters when transitioning from idle to full throttle it is too rich on the bottom. If it just dies when transitioning it is too lean. When you get the low speed needle right you'll need to readjust the high speed needle.
If you get all screwed up and don't know where the needle is set start all over by turning the low end needle all the way in and back it out 2 turns. Turn the high end all the way in and back it out 2 1/2 to 3 turns and start all over.

RE: Difficulty Tuning an Evolution Engine
 

I'll give that a try - thanks!

RE: Difficulty Tuning an Evolution Engine
 

Several things to try:

Leave the glow plug igniter in and throttle up and down again.

- Does the engine die the same way with the glow plug igniter in?

If so, move on...

If not, it MAY be too rich or there is a problem with the plug.

- Since it died with the plug in, follow WCB's advice.... but note the following.

On the Evolution engines the clip that holds the needles is usually too loose, both the high and low speed settings will "walk" as you move the throttle.

I had similiar problems to what you are having and it turned out that the "walking" was throwing the engine off enough to shut it down.

I removed the high speed needle and clip and rebent the clip to make it tighter... then reinstalled everything.

After the engine was adjusted I also installed a piece of cut off exhaust tubing to hold the clip tightly against the needle detents.

I also needed to richen the engine about 1/4 turn past the low idle stop. I undid the retaining screws on the collar and adjusted as needed.

- If all of this still fails, check the fuel / line flow.

Remove all of the fuel lines and tank, and blow through the fittings, etc. Are you getting any resistance?

Also note how the length of the lines adversely affects the amount of pressure that is required by a large degree...

When possible shorten the lines.

RE: Difficulty Tuning an Evolution Engine
 

Thanks everyone, but I think the engine was damaged when the plane was crashed. As I noted, I did not witness the crash but with the HSNV broke off it must have been a bad crash.

While visiting my field I had one of our local engine gurus check things out. He worked with the valves, replaced the plug, blew through the lines, checked the fuel flow, etc and still could not properly tune her - he did everyting WCB suggested.

The engine sounds great, it transitions great, and can run full throttle with no problems. However, at idle it dies after a few seconds unless you nurse it.

He thinks the problem may be that when the engine impacted the ground the shaft may have been pushed back some so there is a small air leak causing it to lean out. (I may not be quoting him word for word but you get the idea.)

Is the engine worth having checked out by the factory? Would it be money well spent or should I just get another engine? A new one is about $80.

RE: Difficulty Tuning an Evolution Engine
 

I don't think it's air leaking in the shaft. It is not uncommon for oil to leak from the shaft so that tells you if oil can get out then air can get in. That's normal and doesn't harm a thing (except make a mess if it drips on your carpet). If it won't idle that can be a symptom of being too lean on the bottom end. It can also be a symptom of being too rich. It will set there idling and load up on fuel and flood itself out. I still say you have a problem in the low end needle valve. You may try a plug with an idle bar if all else fails.
OPjose is right about the spring clip that holds the high end needle valve being too loose. I've seen that a few times on Evolutions. I cut a piece of fuel tubing and using needle nose pliers slip it over the needle valve and clip. That holds pretty well.
I've seen a bunch of the Evo's of all sizes and only seen a couple that didn't perform just fine and that was usually due to a bad plug or a hole in a fuel line or something else real simple.
WCB

RE: Difficulty Tuning an Evolution Engine
 

The original plug had the idle bar so I think I will try to replace that first. The guy who worked on the engine tuned the high and low end - one at a time, and we put several different plugs in, but we did not have the one with the idle bar.

The manual shows the plug as part number HAN3011 ([link=http://www.hangar-9.com/Products/Default.aspx?ProdID=HAN3011]Super Plug[/link]) does not look like what was taken out. Anyone have a link to the right plug?

Thanks to everyone for your help.

RE: Difficulty Tuning an Evolution Engine
 

All the suggestions so far have been great.

Try an OS A3 . This plug will sometimes fix pesky problems. I can't think of any reason for the plug to have an idle bar on this engine.

I've also seen this type of thing happen with bad fuel. Is your fuel old or contaminated? Are you running 15%?

Good luck

RE: Difficulty Tuning an Evolution Engine
 

Thanks for the tip on the OS A3, I'll get one.

It's new fuel (new as in just purchased, just opened) but I don't recall the nitro content - either 10 or 15. I think it is Cool Power for 2 and 4 strokes. I have also tried a different type of fuel too, but don't recall what it is at the moment.

RE: Difficulty Tuning an Evolution Engine
 

The manual is showing the correct glow plug, since the evolution engines do not us an idle bar plug particularly in an upright installation. I do not know what the repair cost would be but if it is more than $45.00 I would go ahead and buy a new engine. Then at my leisure I would try and completely rebuild the engine.

RE: Difficulty Tuning an Evolution Engine
 

Ok, thanks.

RE: Difficulty Tuning an Evolution Engine
 

Try this:

1 Loosen the screws that hold the carb in place

2 Press down on the carb so it is tight against the crankcase

3 while holding this pressure, re-tighten the bolts.

If that doesn't help, do this:

1 Remove the Low End Limiter collar

2 open the throttle 1mm

3 Close the low end needle

4 open the low end needle 1 1/5 (One and One Fifth) turns (this is where it is SUPPOSED to be set at the factory, but a few slipped by with different settings)

5 replace the Low End Limiter Collar.

RE: Difficulty Tuning an Evolution Engine
 

We did everything but the carb and I will try that tonight. Thx

RE: Difficulty Tuning an Evolution Engine
 

Excellent info!

Is the low end needle setting true of all Evolution engines?

I'm having a problem with an Evolution 1.00NX and I have probably moved the low end needle way off, so the answer would be very helpful.

RE: Difficulty Tuning an Evolution Engine
 

I don't know. that is for the TPS, but I don't know if it holds true for all Evo's

RE: Difficulty Tuning an Evolution Engine
 

Thanks...

Clarifications if you would be so kind...

You state:

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2 open the throttle 1mm

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Do you mean the actual throttle intake? E.G. if you look in the carb air intake it should be open only 1mm?

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3 Close the low end needle

4 open the low end needle 1 1/5 (One and One Fifth) turns (this is where it is SUPPOSED to be set at the factory, but a few slipped by with different settings)

---

This with the throttle/intake still at 1mm, correct?

Thanks.

RE: Difficulty Tuning an Evolution Engine
 

Yes to everything

RE: Difficulty Tuning an Evolution Engine
 

There is a similar thread somewhere on RCU about the Evo 100. I forget which forum it's on, but the owner found his 100 had the low needle set with the collar at 3 3/4 turns. He removed the collar and reset it to 1 1/4 turns and adjusted from there. He said the idle was perfect and the top end greater.

RE: Difficulty Tuning an Evolution Engine
 

THANKS!!!

RE: Difficulty Tuning an Evolution Engine
 

Anyone know what the factory default is for the high speed needle?

BTW: I dismantled my 100NX's carb and I noticed that it was as stated, about 3 1/2 turns out on the low speed.

I performed the above reconfiguration, but when I tested flow at the throttle with the 1mm setting, I got none what-so-ever.

I had to back the low speed screw out to about 1 3/4 turns before I could hear a slight hiss with the throttle set to about 2mm.

I haven't tried the engine this way, but this is the mid point of the low speed limiter now.

RE: Difficulty Tuning an Evolution Engine
 

OPJOSE,
I wouldn't worry about the factory default setting on the needle valve. It is a very general "in the ball park" setting. You can do that yourself. Take the limiter off, turn it all the way in and back it out about 2 1/2 turns and adjust it from there to suit your climate, altitude etc.

WCB

RE: Difficulty Tuning an Evolution Engine
 

I had this problem on my Twist 40 with the Evo 46. All it was is not a hot enough plug. It'd do okay on throttle but when you'd throttle back it would die. Use a Hangar 9 2-Cycle Super Plug. They work.
-Eric

RE: Difficulty Tuning an Evolution Engine
 

Yup it was the low speed needle.

Now I can get reliable flights...

I ended up removing the pin from the limiter.

And these things are sold as being pre-adjusted from the factory! Ugh...

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Anyway, now the problem I have is that the low speed needle "walks".

With the heat of normal operation (no it's not too hot), the needle will turn fairly easily.

With the vibration of the motor added to the mix, the low speed needle tends to "walk" now.

Any suggestions on how to firm it up a bit, but still let it move?

I wish Evolution would do away with these limiter collars on everything except the PTS engines.

They are more of a nusiance then they are worth.

Can anyone suggest a replacement carb for the 1.00NX from another manufacturer that would work, (and hopefully not have this problem)?

RE: Difficulty Tuning an Evolution Engine
 

Put a drop of Blue thread lock on the screw. That will still let you turn it, but it will put enough friction on it to keep it from moving on its own.

RE: Difficulty Tuning an Evolution Engine
 

Thanks

I actually put a drop of blue on the needle threads, and this seems to help a lot. I can still turn the needle with a screwdriver.

I don't know if this will hold up when the motor heats up though.