TRM 231 tuning problem

[Bobs]

I have one gallon of fuel through a new 231 TRM motor in a Spectra G. When throttled up to 1650 RPMs at half stick, zero pitch, the motor cuts out and then picks up again and keeps repeating this over and over. My low speed needle is at one and a quarter turns and the high speed is at one and three-eighths. Is the motor cutting out an indication of a too rich setting on the needles? The instructions with the TRM motor are adamant about running the needles leaner than one and three-eighths; however, at the settings mentioned above, the motor is still four-cycling, the plug is dark brown and the base of the plug is wet. Also, the engine temps taken right behind the muffler are always below 220 degrees. I need to know if the motor cutting out is a sign of being too rich, or something more serious. Thanks.

[bigrcr]

You are describing a very rich condition. The instructions (written by me) are to always err on the side of being rich, not necessarily to tell folks to never go any leaner than those settings. As long a you always know where your settings stand coming from the rich side (this method should have you always knowing that you are NOT lean), you should not hurt a motor.

As long as you are not getting glitches causing what you describe, I would say for you to lean it down on the high needle a bit at a time to see if it clears up. If at any of these steps you find the motor being lean or getting worse, go back to the richer condition. I will bet you will get to the sweet spot by using this method. To test the needles occasionally, rich-en the main needle a bit a go fly the model, land and repeat (rich-en, fly and land) until the performance drops a bit and then go back to the previous good setting.

If you have an ignition shield installed incorrectly, it can cause huge problems as well. Correctly installed these shields are wonderful. Improperly installed, the shields are a nightmare. If unsure, cut the tie wrap and pull the shield back down the lead and tie it out of the way, or remove it.

Later,

BIGRCR

[Bobs]

Thanks, John. Allen gave me your phone number a couple days ago but I haven't had a chance to call you yet. This condition of the motor cutting out got worse when I removed the Hatori muffler and installed the stock one; however, with the stock muffler I can clearly hear the four-cycling and know it's running rich. Before changing mufflers the motor was cutting out at the top of every short climb-out. Now, of course, what I'm describing is happening on the ground. I'm getting four-cycling all the way up to half stick, with it improving a little bit once the RPMs approach about 1650. If I hold it at 1650 RPMs at half stick with zero pitch, that's when the cutting out begins. I know the low speed can take just a bit more leaning but the top end is where I'm stumped. I have a Bergen with a stock 260 and had very little trouble getting it broke in compared to the 231. I have not had any glitches at all and am not running the ignition shield. At one point, with the Hatori installed, the plug was actually becoming a dark tan color; however, it was obviously running rich due to the extremely poor performance. It was difficult getting the RPMs up to speed and then right before lift off it would become sluggish and lose RPMs. And again, that was while using the Hatori. I've been convinced all along that it's running too rich but was scared to lean it anymore due to the instructions and the fact that I'm already at one and a quarter on the low speed needle. The Bergen was easier to adjust the needle transition between low and high speed and also the stock muffler made it easier for me to hear the four-cycling. With your instructions to start leaning the top end some more I'm sure I'll get it sorted out now. As I think I stated, I just finished with my first gallon of fuel using 4 ounces of Blue Marble and am now switching over to Amsoil Sabre at 50:1 so I figure the frustrations are not over yet knowing that this too is going to change things. I'm hoping that this fuel switch will help lean things out some before making any further changes to the needles. If not, I will start leaning the top end. Thanks again, John.

[bigrcr]

Forget the low needle right now, it does little at this point. Your experience with the Bergen is what is getting you as the Bergen hovers on the low needle. The Spectra-G does not hover on the low needle because of the 7.15 gear ratio, it was designed that way. The high needle controls the hover and above settings for the most part. The low needle helps a little for transition but this actually occurs below hover RPM unless you are barely turning the head. At that low RPM the model will be bobbing all over the place due to the tight head dampening.

Try the high needle! :wink:

BIGRCR- John Garst

[Bobs]

Unfortunately, John, I could not eliminate the motor cutting off and on with needle adjustments. I spent hours today in an effort to solve this problem by trying every needle combination imaginable: rich, lean and everywhere in between. The results were always the same with the exception of it occurring at different head speeds when changing the needle adjustments from rich to lean. I did notice that when the motor cuts off and on the throttle servo arm is actually moving back and forth. It looks like that's what's causing the motor to cut off and on but I can't figure out how or why it's happening. Any ideas as to what would cause the servo arm to move back and forth on its own? I would have thought the throttle arm would remain still even if the motor were cutting off and on due to the carb adjustment being too lean or too rich. At this point I am at a complete loss as to what's wrong. I do have a Revlock/Stator Gator installed but have not used it during the break-in and even disabled it to see if that had any effect. It did not. The throttle servo is a digital JR 821. The other three are JR 8311s with a 9254 on the tail. Sure appreciate any suggestions you might have.

[rbort]

The throttle servo is junk. Replace the servo. The cheap digital servos don't live well with vibrations. Another cause can be the stator gator wire if its rubbing on something and getting cut, but in your case sounds like you need to replace the servo. Don't use the low end digital servos in gassers, they don't live a long life there. Going with a cheap analog servo is the best bet.

-=>Raja.

[Danyboy]

Bob,

I am by no way an expert on Gasser-Heli's...

But in real-life on aircraft-engines you would have a closer look on the spark-plug.

Just for trying's sake, replace it with a new one and see whether the problem's gone or not.

With my first gasser, I had a faulty spark-plug that made it *very* hard to start and only run in idle. Whenever you wanted to throttle up, it would pick up a little speed but then strangle itself. Since replacement of spark-plug, everything is fine...

Maybe there's dirt in the carburetor's diaphragm? Restricting fuel flow just enough that the engine runs in idle, but has problems with higher loads?

I'm not saying this is the one and only solution, but I learned that if the "quick-hip-shot" doesn't help, it is best to work your way top-down, replacing/swapping units step by step to confirm the troublemaker.

Cheers,

Daniel

[rbort]

Be careful with your needles and engine temperature when you run it on AMS 50:1. It will be more critical then to be correct and with less oil there is less room for error.

-=>Raja.

[Bobs]

Thanks, Raja. BTW, I tried an analog servo, a JR 537, and that didn't work at all. Every time I turned the power on the servo arm would go counter-clockwise well past the shut-off position and then after a couple seconds it would come back to where it should be. I also had the 821 digital servo checked out and there's nothing wrong with it. Also, with the 537 I was unable to program the Revlock to work properly. Tried three times and every time the same results. I now removed the Revlock, re-installed the digital 821 and will try it later today. I'll let you know how it goes.

[rbort]

I had that problem with the 8700g servo on my 1005. Somehow it didn't like the signals from the gv-1 and when I turned the power on it would peg to the end and then go back. I switched to another servo JR2700g and it worked great for a very long time. Recently I replaced it with an 8417 as the throttle servo started jumping around and I thought it was going bad, turned out the gv-1 cable had rubbed on the frame and got cut. Anyway I left the 8417 in there as its doing fine.

On the Spectra I use a different servo, the 537 if I remember right, and it seems to work fine. Its a marriage between the servo and the governor, so if the 537 does not work with your revlock then you need a different model, that all you can do.

How do you know the 821 is good? You can't really check it out on the bench as there are no vibrations to agitate it to fail. Anyway try it again and see what happens!

-=>Raja.

[Bobs]

Turns out that it's not a servo problem but a PCM lockout causing the servo to go to idle and cutout back and forth. After approximately a gallon and a half of fuel the motor is still not running worth a darn. Mixture screw adjustments make very little difference in performance other than idling speed. There's also a metal sounding noise coming from the motor. At the end of every flight since the first tank of fuel I immediately checked the engine temp right behind where the muffler bolts to the motor. It has never gone above 270 degrees and is usually around 225. It has always run filthy rich, even when leaning the needles below one and a quarter turns. This motor runs nothing like the 260 in my Bergen. The 260 is very responsive to every small adjustment to the needles. I've checked to make sure there are no air leaks and there are none. I removed the Revlock, even though I ran it with it disabled, and that made no difference. I removed the Hatori muffler and tried the stock one with no improvement. I've tried every needle combination imaginable from rich to lean and everywhere in between with no improvement. I've also changed spark plugs, which brings up another issue. From my understanding, Al does not run the motors after modifying them; however, when I received my motor the spark was NOT new. It had obviously been run before. A club member also has a new Spectra G with the 231 TRM motor and his runs great - no comparison to mine. He's even using my identical throttle curves. He has also checked my setup over and feels that something is wrong with the motor. In fact, he's the one that mentioned the metal sound coming from the motor. I have talked to Al on a few occasions and the last time he suggested I contact John Garst because he felt the problem was in my setup. I disagree. This is not my first gasser and is actually the 7th helicopter I've built. It is not a setup problem. I have removed the motor and am returning it. At this point, I'd prefer a stock motor over the modified version. Too much frustration to continue chasing this problem. For the entire first gallon of fuel, after each and every tank of fuel, faithfully, I waited at least a half hour to an hour before running another tank of fuel through it. And each and every tank was a pain in the butt trying to get the motor up to speed and keeping it there in order to just hover. Break-in on the 260 in the Bergen was a piece of cake compared to this motor. What a shame because the build on the Spectra G was a breeze and then dealing with this has really soured the experience.

[rbort]

Sorry to hear about your frustrations. With persistance you will succeed, trust me on that one! I heard about all those people having issues with the Spectra's before mine and I said to myself I'm going to get one and succeed with it, and I did! 279 flights now and its my #1 machine.

You need to break down the issues into smaller problems and solve them one by one. Fix what you know is wrong first as compounded problems are confusing. If you have lockouts happening, concentrate on that and get it solved. Once you got that out of the way it will pave the road for you to the next milestone, getting the engine running well and such.

You may have a bum motor but its not highly likely. Maybe you have an airleak or a bad carb, etc. A simple test would be to try things like the Z-rc insulator or a new carb. Also your fuel line can be restrictive if you are using the stents clunk. Or the vent can be blocked if you are using the 1 way valve. There are many variables. Variables make confusion, and confusion makes frustration which leads to people giving up.

I wish I was near you so I could lend a hand and fix your machine for you. I went to Jamaica in the spring and 1 afternoon with a guy's Spectra there I had it running better than he ever had in a year's time of futsing around with it.

Really the moral of the story is don't give up, break down the problem in smaller pieces, and tackle them one by one to solve the issue.

-=>Raja.

[ClayK]

I agree with the z-rc insulator, my engine on my Spectra was being difficult tuning. Pulled the block and found it warped. Put on the z-rc insulator and gaskets, no problems since. I am also running a TRM 231. After getting the motor locked in, it's been a breeze. I like the model, she's just a bit heavy. After flying nitros all day, there is definitely a curve to get back into flying the model right.

[rbort]

Clay:

Are you going to be at the MHA FF this Friday? If so see you then!

-=>Raja.

[ClayK]

Yar, I will be there. Not sure if the Spectra is coming though, I may not have room. I'm planning on bringing my Stratus, Tempest and my TRex pseudo-V2.

[rbort]

Up to you! I'm bringing my Spectra, the 1005 and maybe the T-rex.

If you bring it you can show me how well its going for you! I know you like higher rpms than I do so I'd like to see yours perform!

-=>Raja.

[Bobs]

Thanks to you both. I won't give up, just a little disappointed right now. I am running the z-rc insulator and removed it to make sure it was sealed. It was. I also ran the motor with the one-way vent removed and no change. The Stens clunk is something I have not checked yet, but I will now. I have sent the motor back to TRM for Allen to check out. The carb is high on my list as the tuning problem but then there's the lockouts: a bearing, timing - I'll leave that for Allen to figure out. Thanks again and I'll post the results when I find out what's wrong.

[Bobs]

Haven't got the motor back yet but the word from Allen is that the carb was causing the problems and he also installed a new ring. The motor checked out fine internally but when he put a new carb on it made a significant improvement. I'll post the results when I get the motor back, hopefully, some time this week. I've also switched over to XPS so I'm anxious to get everything back together and try it out. Later.

[Bobs]

Well, today is Saturday, 6/16/07. In my last conversation with Alan on Thursday, 6/7/07 he stated he'd be shipping the motor back to me the next day, Friday, 6/8/07 and that he would call if there were any problems. Not only have I not heard from Alan (again) but I still do not have a motor. I live in Northern Minnesota and our flying season is very short. An unnecessary delay like this is most inconvenient. I'm not frustrated anymore, I'm down right pissed off. He was waiting for a ring to install on the motor. I have no idea why he would have to install a ring on a new motor that he said was broke in so well. Also, this guy is supposed to be an engine builder and he doesn't even carry a ring for a Zenoah 231? He also doesn't carry the stock WT 643 carburetor but has the 644 used in boat applications. Shame on Miniature Aircraft for recommending TRM's product to their customers. With their reputation on the line they should stick to stock Zenoah motors and let the customers decide on a reputable vendor for modifications. Alan's handling of my particular matter is inexcusable.

[j.8]

Hi Bobs

Sorry to hear about your delay with your motor.

But I`m sure Al is only trying to do whats best
for your engien.

A few month`ago I needed a new piston for my TRM,
and Al send me one for free, so he cares about his costoumers.

BTW we allso have a very short flying seson here in Denmark,
and I understand you, It could allso be a post service problem

Regards Bo Denmark

[bigrcr]

Bobs,

Sorry to hear of your problems. I am quite sure that Al will take care of your problem soon.

BIGRCR-John Garst

[Bobs]

Today is Monday, June 18th: no word from Alan and still no motor. It's now 11 days since Alan supposedly shipped the motor back to me. :arggg:

[Bobs]

Wednesday, June 20: no communication from Alan and still no motor. The word I get from Miniature Aircraft is that TRM no longer modifies motors for them. Gee, I wonder why?

[rbort]

Any news from Al? I sent him a PM on RR that you were looking for him and your engine as a heads up. Hopefully he took care of you.

-=>Raja.

[Bobs]

Thank you, Raja. I appreciate the help. Yeah, he finally got ahold of me. Turns out he's managed to somehow place the blame on me for not calling him. The whole thing has turned into a can of worms. Unfortunately, the bottom line is that as of today, Friday, June 22, I still do not have a motor and it sounds like it could be another week or so before I get one.