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MOKI RADIAL Care and Maintenence

Old 05-19-2015, 02:02 AM
  #3351  
Tuggs
 
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Originally Posted by Jaketab
Getting ready to maiden a new Delro Models Turner W4X with a 250 and older top hat ignition and fuel pump.
Stihl Ultra at 45/1 with 90 octane no ethanol gas. Voltage regulated to 5.5v. Motor is not new.

Some issues with the motor I would like a little help with.
1. Running on the ground with the cowl in place, I get a lean condition - possibly as result of heat build up in the cowl.
2. The motor runs like a gyro except at the mid range 2500 - 3000 rpm range where the motor shakes like a wet dog.

When running without the cowl the motor does not sag at max rpm. After about 5 - 7 minutes running with cowl in place, that is when I am getting the sag at high end.
The cowl has baffles in front of the motor and I have 4 vent louvers around the cowl. I will be installing 3 more louvers.
As for the 1st issue, should I expect better cooling when the plane is in the air as opposed to running on the ground ???

As for the 2nd issue, no amount of needle chasing will completely cure the shaking at mid rpm. Current setting for the needles is H - 1 1/2 and L - 3/4.
Since this motor has the older ignition, could that be the cause mid range issues? Is the voltage input a possible cause?

Thanks for any suggestions.
Regards - J Tab
Hi!

I am almost certain that the old ignition has nothing to do with your Problem. I am running new and old ignitions and there is no difference. I would get rid of the pump, it is absolutely unnecessary as long as your fuel tank inside the plane is mounted a little bit above the carburator. The pump can cause more trouble than it actually helps.

Although I believe that the cooling will be better once the plane is airborne, there is most likely not enough space for the exit air. By the way, you can easily Close the additional vent holes you have in your baffle. The air that can enter the cowl around the cylinders is enough. I am not sure, but I think you Need at least 2 if not 4 times the space for the exiting air compared to the air entering the cowl.

Most likely your engine is getting too hot. Did you check if all cylinders are running?

/T
Old 05-19-2015, 04:12 AM
  #3352  
Maxam
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Jtab, 1. does the carb suck air from the cowl. If so, do you have a hole in the firewall at the back of the carb. If so I can send you a Kunkle venturi to try that will suck cool air from inside the fuse.
2. Move the prop 90 degrees. It may not be dynamically balanced. The engine is not dynamically perfect. Changing the prop position can anti phase out the vibration period. Been doing this for years with many engines. If not better do 180 degrees.
3. In my experience the fuel pump is a great benefit but on only 4.8 volts.
4. Richen the high end needle a bit?
5. Keep the top hat cool inside the fuse. Hope all helps -Tom
Old 05-19-2015, 08:44 PM
  #3353  
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i wrapped it when it was mounted on the plane and the complete exhaust system installed. it takes some time but completely worth it in my opinion. Also did it on my airworld fw190 that i am working on.
Old 05-20-2015, 11:27 AM
  #3354  
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Tuggs and Maxam,

Thanks for the replies. I'm fairly certain now that the overheating and sagging was due to ground running too long.
Others with this plane are not experiencing overheating with no mods to the cowl.
Temps should be OK with the 7 louver vents around the cowl. Each opening for a vent is 2 1/2" x 2 1/8".
This is in addition to the exit area that surrounds the back of the cowl.
The louvers do an excellent job of extracting heat.
The ignition module is inside the fuse away from engine heat.
The carb is drawing air within the fuse. I have a velocity stack on the carb.
I will try rotating the prop. Will reduce voltage to ignition to 4.8v the next time I have down for service.
Could the mid range missing may be a carb transition issue between the L and H jets???????

Regards - J Tab
Old 05-20-2015, 04:50 PM
  #3355  
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J tab, What helps the carb to work better with these engines.....sorry if you are already aware of this.....the choke area is too large for these engines. Adjust the full throttle on your transmitter so that the carb butterfly opens only 3/4 open then retune. I have mine adjusted less than that! 5/8 ths open. I barley loose any power and the midrange is quite a bit better with much better transition......really. Recall I have the 215's. If yours is a 250 3/4 might be better than my setting. I run my ignition at a regulated 5.5v. I think your plane is really cool. I like those vintage racers. -Tom
Old 05-21-2015, 04:30 AM
  #3356  
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Quite familiar with my two 250's but just received my new 180 and wonder if anyone has a good suggestion for three bladed prop? I don't like to over rev these radials so better with lower rpm as long as it's not too much which runs them hot.

Is the 26*14 good or can it handle even larger?
Old 05-21-2015, 05:56 AM
  #3357  
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Has anyone tried a 2-blade 32x22 on the Moki 250?

Beila recommends this prop for the 250, but it sounds like way too much pitch to me. My plane is a 55 pound CARF Pitts, so a lot of drag already without the prop. I don't want to cook the engine, but I do want a little more speed than the 32x18 is giving me today.
Old 05-21-2015, 08:15 AM
  #3358  
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What helps the carb to work better with these engines.....sorry if you are already aware of this.....the choke area is too large for these engines. Adjust the full throttle on your transmitter so that the carb butterfly opens only 3/4 open then retune. I have mine adjusted less than that! 5/8 ths open. I barley loose any power and the midrange is quite a bit better with much better transition......really. Recall I have the 215's. If yours is a 250 3/4 might be better than my setting. I run my ignition at a regulated 5.5v.
Tom - Your idea makes reason in that the last few clicks of the throttle do not increase the rpm.
About 4800 rpm is the static max I'm getting. (Xoar laminated 32x18) If I open the throttle just to the point of max rpm and stop the servo travel value at that point, that should be the setting where I will retune.
Most likely will find that the high needle can go leaner.
My motor has excellent transition, but it's just that mid-range missing that I would like to eliminate.
As I listen to other Moki engines in posted videos I hear that same mid range missing or cutting out.

Reyn,

I used to have a Beila carbon 32x18 and the engine rpms seemed to be on the high side.
Hope you find the 32x22 works for you.

Thanks - J Tab
Old 05-21-2015, 04:06 PM
  #3359  
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I was told that you shouldn't run on the ground for extended periods of time as the cooling would be inadequate. I definitely expect you will get better cooling in the air.

Whit
Old 05-21-2015, 10:00 PM
  #3360  
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Affas, I run 26x16 on my 150.
Old 05-22-2015, 05:27 AM
  #3361  
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Yes J-Tab, The missing in the mid throttle is due to the Walbro design. The carbs on 4 strokes go too rich in the mid range thus causing the rough running. That is why when the carb is adjusted for 3/4 open it, as you said, the high speed needle can be leaned in for proper mixture for the top end. The good news is it will also lean the midrange so the engine will run better at part throttle and yet loose little to no power. I have a saito 325 radial and I had to use a 24 oz tank because the lousy carb on it goes very rich in the midrange where you want to do most flying. I bought an OS carb for the 240 Pegasus and turned it down on the lathe to fit the Saito. The mid throttle is greatly improved and now I have longer flight times on 16 oz!!! The engine is so much more enjoyable to fly. I am with you, on youtube most Moki's are very rich and run poor at part throttle settings. The turbulator is a great for midrange running due to the evenness of fuel distribution. It sounds like your plane is nearing completion. I look forward to hearing a flight report. -Tom
Old 05-22-2015, 12:37 PM
  #3362  
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I only have 150s, not 180s, but I strongly recommend that you consider something like a 28x14 vs the 26x16 IF you are flying a plane that can stay in the air at the airspeed that prop will produce for you. I found that for my early SN Moki 150s a 26x16 still revved my engines into overheating at the lean setting that was required to get cylinder number three to run almost all the time (burbles at mid throttle wouldn't you know...). With the higher diameter prop RPMs stayed down in the 4500s and so far no overheating. I am speaking of two bladed props, convert for three blade and then see what Dr Gotz has in stock. Vogelsang aeroscale.com

Just my $.02 worth the price you paid for it.

Whit

Originally Posted by affas
Quite familiar with my two 250's but just received my new 180 and wonder if anyone has a good suggestion for three bladed prop? I don't like to over rev these radials so better with lower rpm as long as it's not too much which runs them hot.

Is the 26*14 good or can it handle even larger?
Old 05-24-2015, 04:52 AM
  #3363  
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I have a 180 and use a 26x18. Seems to work well.
Old 05-24-2015, 05:43 AM
  #3364  
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I just purchased a Moki 100 twin. Have not seen a lot of comments on the 2 cylinder models and I suspect there are fewer issues with those as comparted to the issues with 5-7 cylinders.

Throttle transit time: Has anyone experimented with setting a throttle curve and setting a slower time on throttle tansit time? Gerhard with Toni Clark recommends for the Vlach 120 using a 1 second setting on throttle transit time along with a deep throttle curve to get the engine to transition well from lo to hi and back. I used this on my Valach and it really worked. Engine transitions well and throttle response still feels instantaneous. Here is the link to the Vlach 120 instructions from Toni Clark and page 8 has the suggestion on 1 second trnasit time: https://www.toni-clark.com/ftp/VM120Anleitung_en.pdf

Before I did this timing, if you rapidly moved the throttle stick up and down, the engine would quite at random: no amout of needle tuning could find a happy setting. Addted the tranist time and the engine still feels like it is responding well but no tendency to quit in transition setting, even very fast jerking of the stick.

I have not run the Moki 100 yet but will see if this is needed. Will also be looking at this aspect of setting up engines in the future.

My valach is on a 40% Paolo Severin Eindecker so I do very little 3D.
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Old 05-24-2015, 12:03 PM
  #3365  
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Macboss,

The throttle response on my Moki 250 Radial is immediate with no lag or stumbling. However, I use a 1 second transition speed and a throttle curve for the following reason. A smoother throttle transition helps prevent the powerful motor and 18 pitch prop from torqueing the plane to the left upon acceleration. In addition, if for example, the engine was slightly mistuned, a slower throttle response might prevent the engine from cutting out and stalling. The same holds true for de-acceleration. The throttle delay and good throttle curve would be beneficial anyone who flies an airplane in a scale like fashion. Slowing the speed of all control servos on an airframe can give rise to much smoother flight patterns.

Regards - Jaketab
Old 05-24-2015, 12:13 PM
  #3366  
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Jaketab,

Thanks. Using the features of having a digital system to better manage servo control adds another dimension to setting up a plane for best flight performance.

That sounds like an advertisment for a radio system.

Ed
Old 05-24-2015, 03:26 PM
  #3367  
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Ed, Twice on this thread I inquired about the 100 twin. No responses. Nice to hear about one. Do both cylinders run evenly, nice to run etc? I too on my 9503 JR radio set a slower servo speed to accelerate but the return to idle I keep a bit faster for safety. Does make the engine run nicer. -Tom
Old 05-24-2015, 03:34 PM
  #3368  
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Tom,

I just received the engine and have not run it on my test stand yet. Maybe in a few weeks I'll get to it.

Ed
Old 05-24-2015, 11:32 PM
  #3369  
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Originally Posted by GeorgiaFlyer
I have a 180 and use a 26x18. Seems to work well.
Three bladed propeller?
Old 05-25-2015, 05:45 PM
  #3370  
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Originally Posted by affas
Three bladed propeller?
no its a Fiala 2 blade. got it from Volgelsang
Old 05-30-2015, 10:08 AM
  #3371  
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Default Carb tube on Moki 100

Getting ready to mount my Moki 100 boxer on test stand and noticed it does not have a carb tube running to the back of the crankcase.

Here is a picture of my engine rear view:



Here is a picture of an engine I saw on youtube:


I've sent Gotz a note. Anyone know if my engine is acceptable without the carb tube.

I also noted that my engine has the hall effect sensor set up on the prop washer and the one with the carb tube has the sensor off the side of the crankcase just behind the cylindors.
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Old 05-30-2015, 12:45 PM
  #3372  
Jaketab
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FYI. What a difference baffles and vent louvers make for cooling a radial engine. Had the 1st flight on the Delro Turner W4X this week. Before mods, temps on the ground measured with a laser gun through the spinning prop measured 205 - 215F. The temp range after landing on the maiden flight were 180 - 188F. The engine ran well for the 1st flight.

Not to bore you with off topic details, but the plane flew well, however, my biggest fear was present -- Tail heavy planeThe C/G called for 210 mm aft of leading edge. I balanced at 195 to 200 and the plane was still tail heavy.
The plane handled very well above low throttle, and the stall speed was slow, – but -
Most of the 12 minute flight was spent setting up for landing (nerves) because upon chopping the throttle, the plane would climb upward.
With only 35 degree of flaps, the approach was very long to bleed off speed.
This made for a very difficult landing. I had a 3% mix of down elevator with the flaps, but this was not enough.
The plane is probably tail heavy even balanced at 195 – 200 mm aft of the leading wing edge.
Others I have consulted with say that once the plane is dialed in, it's like a "Trainer on Steroids."
Next flight will have more nose weight and more down elevator mixed in with flaps.
Hope to post some video soon.

Regards - Jaketab
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Old 05-31-2015, 01:25 PM
  #3373  
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Originally Posted by Jaketab
FYI. What a difference baffles and vent louvers make for cooling a radial engine. Had the 1st flight on the Delro Turner W4X this week. Before mods, temps on the ground measured with a laser gun through the spinning prop measured 205 - 215F. The temp range after landing on the maiden flight were 180 - 188F. The engine ran well for the 1st flight.

Not to bore you with off topic details, but the plane flew well, however, my biggest fear was present -- Tail heavy planeThe C/G called for 210 mm aft of leading edge. I balanced at 195 to 200 and the plane was still tail heavy.
The plane handled very well above low throttle, and the stall speed was slow, – but -
Most of the 12 minute flight was spent setting up for landing (nerves) because upon chopping the throttle, the plane would climb upward.
With only 35 degree of flaps, the approach was very long to bleed off speed.
This made for a very difficult landing. I had a 3% mix of down elevator with the flaps, but this was not enough.
The plane is probably tail heavy even balanced at 195 – 200 mm aft of the leading wing edge.
Others I have consulted with say that once the plane is dialed in, it's like a "Trainer on Steroids."
Next flight will have more nose weight and more down elevator mixed in with flaps.
Hope to post some video soon.

Regards - Jaketab
Use a CG couculator to determine the CG, never rely on the manual.

TB
Old 06-03-2015, 06:15 PM
  #3374  
Maxam
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Ed. I am as suprized as you are that one engine has the tube and the other does not. I did get a Kolm and the carb does not have a tube and uses the engines intake pulses to pump the fuel. Maybe this is what they are doing. I did find out the later engines have the Hall effect sensor on the crank inside the engine rather than on the front like a DA. -Tom
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Old 06-03-2015, 06:17 PM
  #3375  
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Maxam, thank you.

I'll set the engine up in a test stand next week and will see. I'll report results.

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