butlern

My Feedback: (15)

Unlikely it will sell given all the background info I've just given, hey?

I'll send it for evaluation, but whether I send it to Goetz or Mike remains a question.

StuartMackay

If you cannot get your local dealer to repair it for you, the mail address for factory repair returns is:

moki-modell
H1118 Budapest
Budaoersi u 48-50
HUNGARY

Mark for the attention of Zoli Horvath.

germrb

My Feedback: (3)

Noah,

Take a very deep breath and count to a zillion or find some good weed. I don't think your problem is a mysterious as it appears. From every thing you have discribed, you have a very hot engine that may need some fine tuning. First of all, invest in either an IR pyrometer (Hobbico) or some Eagle Tree data recording equipment. http://www.eagletreesystems.com/Plane/plane.html

Start by checking indvicidual cylinders for temperatrue. The #1 (top) cylinder will be the hottest and should be maintained below 230 degrees F Max.!!!. The coolest cylinder will be the #3 (clockwise from the cockpit) and is prone to dropping out because of inefficient combustion and excess oil. The trick is to get the #1 below max temp and the #3 above 170 deg. F Its a balancing act. If the engine overheats (#1 approaching 300 deg) the power will drop and its almost impossible to restart until its has completely cooled down. Unlike most engines, don't lean the bottom to the point where you just get crisp transition. If anything richen the low end until it starts to get sluggish and then lean it 1/4 turn or so. It sounds like you have the top end slightly rich which is good. With a 26 x 16 prop, 4600 rpm sounds about right for the top end. These engines have much more torque and run slower then 2 stroke engines. Also, 4600 will be 5200 to 5500 when it unloads during flight.

OIL: For brand new engines I would avoid full synthetic oil (regardless of brand). I prefer a pure mineral based oil, which allows quicker ring seating and cooler operation. The only brand I am aware of that is not synthetic is Yamalube 2R. I have has excellent results with other engines. The radials don't tolerate excessive oil in the #3 cylinder, so I would suggest 40:1, rather then 32:1. I try to run at least 5 gallons of mineral base before switching to synthetic.

Having said all that, I have had almost the exact same problem with a 250 in a 33% WACO and I am seriously considering a fuel pump and turbulator to improve the engines overall performance. I have attached some data from my Eagle Tree system that provides actual flight conditions. Temp A is the #1 cylinder and Temp B is the #3 cylinder. It is almost impossible to determine the flight operating conditions from ground data. The first chart is data from my first flight this year and is the correct temperature profile. You will note that the #3 cylinder appears to have dropped out near the end of the flight. The second chart is a month later and is much too hot. I found that the air tube had become dirty which explains the continuing rise in temperature. The ambient temperature was higher, but it doesn't explain the change in performance. The second chart was the result of making adjustment during several previous flight and the day I flew it there was every indication that engine was operating prpperly (immediately after landing the top of the cowl was barely warm) So, you can imagine my frustration when I got home a downloaded the data.

I certainly don't think you need to go to the expense of sending the engine back to TBM, based on what you have discribed. But, get some sort of temperature measuring device to eliminate guessing.

Good luck,

butlern

My Feedback: (15)

Sound advice, Bob, but nothing really new there. Although I posted this exact info earlier in this thread, I'll post the letter I sent to TBM detailing my issues:

> Hi, Jeff,

> I have been having problems with my 150 radial... I am only getting 4600 rpm
> with the recommended 26x16 Bambula... And my IR temp gun shows that it's
> only running on 4 cylinders. I average 220-230F on all but the no. 3
> cylinder (which measures 90-100F). I am calling no. 3 the cylinder at 7
> o'clock when viewed from prop hub.
>
> I purchased the motor in February 2009 from RC Showcase, but I have only
> recently finished my model, so I only recently fired the motor for the first
> time.
>
> Although I plan to soon call you to discuss trouble-shooting, I first was
> wondering if TBM will honor the warranty should something really be wrong
> with my motor.
>
> I should say that I have checked several potential explanations for the lack
> of fire in cylinder no. 3:
> Compression good (no apparent stuck valve)
> Valve lash adjusted appropriately
> Ignition module good (I swapped it with someone else's Moki 150 module)
> Spark plug (NKG-CM6) changed/swappedno help
> Ignition battery started with 4.8V 4200 mAh, changed to 6V 4500 mAh
> regulated to 5.95Vno help
> Fuel (91 octane, Stihl HP Ultra synthetic oil) changed from 30:1, to 40:1 to
> 50:1no help
> Needles low is 1.25 turns, idles at ~600 rpm, high maxes out at 4600 rpm
> at about 1.5 turns. No amount of tuning (either needle) resolved the issue
> with no. 3.
>
> My concern is that the coil in no. 3 is bad/weak. But I'm not sure if there
> is a way for me to rule this out without sending you the motor.
>
> So those are my two questions: warranty coverage in this situation, and is
> there a way to check the coils?

I've been through it over and over.

Mike responded by suggesting that I check the resistance across the plug cap. Mike said that there should be 1.2-1.5kOhms resistance between internal spring and outer surface. Here's what I found:
No.1 = 1.177k
No.2 = 1.206k
No.3 = 1.162k
No.4 = 1.154k
No.5 = 1.162k

He also said beyond that, try a turbulator (which I have ordered). Mike went on to say that if the turbulator didn't help, then send TBM the motor and they will evaluate it.

I reported those values to Mike and Jeff at TBM, asking whether those were indicative of a problem, but no reply came (They suggest nothing out of the ordinary to me).

Sending the motor off to TBM is of course logical, but again, I estimate that this will cost me an additional $200-300 (minimum)... And what happens if if they cannot solve the problem? I'm guessing I'm out of luck and out of even more money. That's a pretty bleak outlook, but my attitude has degenerated over these past 7 weeks of trouble-shooting this motor. No one I know (mechanics, engineers, and 4 Moki radial owners, included) has been able to solve the problem.

Will try the turbulator as soon as it comes (2-3 weeks).

Alex Louw

My Feedback: (1)

Hi Guys

Well the GeeBee is finally ready and I have a few questions for you guys.
First I took your advice and turned the collector ring so that cylinder one with the emblem is on top.
I have 2 Props and want to know which will be better
Menz 34 x18 or 3W carbon 32 x 14
I will run 40;1 oil ratio.

At the moment the cowl is not ducted, should I duct it or run the engine as is and see how it performs.
I ordered one of the fuel pumps and will use this as soon as it comes.
You guys said that there is grease in the engine how will I know when it is time to send it for a service and where would be the best place to send it.

At the moment we have temperatures ranging from 45 to 50 C at our field so it is very hot. I might wait a month or two to run her when it starts to cool down.

I think the GeeBee will be a bullet with this engine.

Regards
Alex

germrb

My Feedback: (3)

Noah,

Sorry for the duplication. Sounds like you have covered all the bases. The temperatures you're quoting are right on target, so overheating doesn't seem to be the issue.

I wrote to Jeff about over a week ago about my heating problems and have been met with nothing but thunderous silence. Hopfully, you'll get a response.

germrb

My Feedback: (3)

Alex,

Sound like you're making great progress. The pictures look great.

If its 45 to 50 C, I wouldn't even go outside to say nothing about flying. Radials have a tendency for overheating and those kind of temperatures would be really hard on a new engine.

The 32 x 14 would probably be easier on the engine during break in.

Alex Louw

My Feedback: (1)

Hi Bob

Yes the temperature here is crazy. On some of the evenings we get down to 40 just before sunset. But we are all crazy and still fly most days. You sure get good at tuning engines as they overheat unless perfectly set up especially when we do 3D.
This engine is used and have about 20 hours on it.
The guy ran it with the engine in the inverted position and he said the only thing was, was that it leaked oil from the small pump when it was not running.
Do I need to replace oil or grease in the pump or not?
He sold me the 34x18 as this is what he used to runon it.
My setup is with a 2500 2 S lipo with a 5 volt regulator.

To start it just to confirm. Close the choke flick it a few times till it pops and then open choke and start?

Will do the CG tonight and then start on the Rare Bear I have a NIB 250 waiting for this one.

Regards
Alex

germrb

My Feedback: (3)

Alex,

If the engine has that much run time the larger pitch should give you better performnace in the GeeBee. I run a 32 x 18 on my new 250 (5 - 10 hours runtime) with good results. I would pay very close attention to engine temperatures in that kind of heat.

You are correct on the starting procedure. I'm lazy, so I use a 24 volt starter on mine, instead of proping it by hand. With the compression stroke in multiple positions, its a bit different then a standard two stroke.

The grease that gets into the air pump line is from thats applied to the cam during engine assembly also some of the residual oil from the gas/oil mixture. The tube should be clear, if its not replace it. (3 mm) Greasing the cam is not a routine maintenence item, but cleaning the tube should be done periodically. Remember, any blockage of the tube will severely lean and overheat the enigne.

AH-64_d

You may wish to consider use of Never Seez on your spark plug threads. It is an anti-seize and extreme pressure lubricating compound good to over 2000 F. I used it to good effect in air-cooled automobile engines for decades.

fredo

Hi Alex
Your Gee Bee looks beautiful. I had one and had a blast with it before I had a little accident. Since then decided to move on to another project and sold some of the stuff. Your Gee Bee looks like a Comp Arf one. If yes I can sell you a spare undercarriage for a good price in case you were interested.

Cheers

Alex Louw

My Feedback: (1)

hi fredo

Yes it is a comp arf. I have actually had her for close to 7 years. I think it was on the start of comp-arf just after fiberclassics.
Yes let me know about the gear as I might get a second one. Just love this plane. Had her flying with a 3W 140 then 150.
Maybe a simple question. Moki radials as sold by airworld is made by Moki Hungury or not as I see nothing on their site about radials and they have a message saying that they have nothing to do with the moki brand airworld is selling?

Regards
Alex

samparfitt

My Feedback: (43)

Initial moki 250 engine testing:
Yesterday, I was only getting 2000 rpm's and hope some possible solutions will be posted on getting a lot closer to the specs of 4300 rpm's.

This morning, I've been running the engine using a solo 32" 3-blade (paddle blades) at 12 pitch (units = 9.5).
Specs say about 1.5 for H and L.
Mine was L=0.9 and H=1.7
I changed L to 1.5 and the engine was much easier to start (no starter needed this time as was necessary, yesterday).
The engine has easy access to adjust the needles while running so I moved L to 1.7 (idle went down so I increased trim) to maintain about 800 rpms.
The rpm still went to around 2100 ( so I moved the 'H' up as well as down about an 1/8 turn to get more rpm's but on the lean side, rpm's went down at around 1900 and no change on the rich side.
Using 1/8" tubing with a T having a 3/32" ID and tank on CG of comparf F4U.
Fuel line routes out the top of the fire wall and then to the bottom of the carb when the inlet is located. Ignition is mounted inside the fuse.
All cylinders are firing with temperatures from 210-240 degrees.

nine o nine

My Feedback: (1)

Sam I've never used a 3 blader on my 215 so I have no numbers to guess what you should be getting RPM wise other than I'm sure you need to get at least 4000RPM. Sounds to me like you have at least one cold cylinder. Start there for a solution. Mitch

samparfitt

My Feedback: (43)

nine-o-nine:
I forgot to mention that all cylinders are firing as temperatures are 210-240 degrees (lower temps on the bottom cylinders).

germrb

My Feedback: (3)

Sam,

I have a 250 and use either a 32 x 12 or 32 x 18 two blade. The 32 x 12 tops out at about 4800 to 5000 on the top end and the 32 x 18 at about 4300. Your 3 blade it is probably too much prop, particularly for a new engine. You might try lowering the pitch to 8 or try a 2 blade.

Your first LOW setting was much too lean, as you discovered. I suspect the HIGH end is also too lean. Try a coulple of 1/4 increases until the top end drops. At that point you would have a nice rich setting for breakin.

Caution: Keep close tabs on the #1 cylinder temperature. You should keep it below 230 deg. F A lean engine will overheat very quickly, particularly on the ground.

Good luck,

nine o nine

My Feedback: (1)

One idiosincracy that has reared it's head for a few users is that after a run the motor won't start....won't fire....won't do anything whether by hand propping or electric starter.
Some of us have thought that the iginition module may be affected by heat but I have a different thought. Of course the ignition can be checked by pulling a couple of plugs and checking for spark. If there's ignition I'm thinking that heat is causing a carb vapor lock. That big ol' exhaust ring surrounds the carb and I can guess how hot the area around the carb gets. Compounding the problem, at least in my mind's eye, is that baffeling the cylinders for cooling is good for them but what about blocking cooling air to the exhaust ring??? Any thoughts Mr Mackay??? Anybody care to chime in?
One thing is that I've never had this type of problem with my 215 so I'm often asked at the field to help others. I love to lend my knowledge where I can but I really feel awkward when I try things but they don't work. Mitch

samparfitt

My Feedback: (43)

Bob,
That sounds good on reducing the pitch: I'll try a 10 setting.
I hear ya' on overheating: I don't run her very long.
The test sheet that came with the engine said they had 110 C which is about 230 F.

Mitch,
I'm hoping my functional cowl flaps route a lot of the heat quickly since all sides (save about 4" on top) are open.

samparfitt

My Feedback: (43)

Engine test (cont)

Reducing the pitch 'did it'.
I dialed in a 10 pitch (8 1/4 on the dial) and now get 800/4130.
Since the factory test sheet had 4300 on a 2-blade, I'll stick with the 4100 for the 3-blade.
The engine is extremely easy to start: choke on, ignition on and flip a few times until she 'spits': Choke off and a few more flips and she's running. I haven't had any kickbacks but I wear a glove since I'm unfamiliar with 5 cylinders 'habits'. It doesn't take much to start the engine and the start is quick (and you don't think it is going to start).
Cylinders head readings were also good: 210 for top cylinders and 180/190 for bottom (they cool down fast as I checked the top cylinders first, and after checking the bottom cylinders, the top ones were also down to 195).

Test 02 video:
interesting: putting the choke on to stop the engine takes a few seconds.
http://www.youtube.com/watch?v=v5JFXI8MfdI

Solo props:
fyi:
pic 1/2:
Make sure you read the instructions for tightening the 12 bolts and prop shaft because the 'logical' method is incorrect: The prop shaft needs to be tightened on the engine first and then the twelve #6 bolts around the hub, repeating this sequence until all are tight. The prop shaft gets tightened first to insure that the two hub halves are 'square' to each other (equal gap on all sides between the props). The sequence I used on the #6 bolts was the two center bolts on each side was first tightened on all sides and then the two outer bolts on all sides until all was firm. I then repeated and tightened the prop shaft (which is loose after the 12 bolts are tightened). This process is continued until all is firm. (don't over do it as there should always be a gap between the two hubs: if there isn't a gap, it means the props are not making firm contact with the hub and must be replaced)

germrb

My Feedback: (3)

Sam,

Congrats!! Sounds great, bird looks great.

samparfitt

My Feedback: (43)

Germrb,
thanks,

=========
Scott Prossen just called me and my results aren't logical and we have no explanation.
A change of pitch of two shouldn't produce such dramatic results as the prop pitch was the only change made with no adjustment of the needles. Scott said his solo zero point was not zero so possibly I really had a 16 pitch instead of 12 (the side view did look large as can be seen in the first engine test video).

fredo

Timthetoolman1

My Feedback: (6)

Samuel, your Corsair looks great. I wish I could see the maiden in person : )

I started up the 150 yesterday. The prop is a 24x16 from Vogelsang.
Straight from the factory with the pump it is spitting out a lot of oil/gas because I have the pump on it and didn't adjust the carburetor. After I have about 45 minutes of break in I'll lean it out. I'm getting about 900 at low throttle and 4400 at high throttle.
[link=http://www.thehog-shop.com/images/tims/moki.wmv]Here's[/link] a short video (sorry about the quality, I think I compressed it too much). That black line under the stand is actually Tygon that got oil soaked.

Tim

(Correction, it's a 24x18).

germrb

My Feedback: (3)

Tim,

Good video. Have you run the engine without the pump? I would be interested in your opinion about any performance improvement. I've got a 250 that I am going to incorporate a pump into and would like to have your input.

Regards,

Scott Prossen

Hey Tim,

Cool video and love the pump setup! Definately got a lot of leaning out to do if your at 4400RPM. I run a 26X16 and no pump and with factory settings I'm getting 5300 to 5500 RPM. Good luck and keep us posted. Looking forward to your future posts!

Round Engines Rule,
Scott