Straightleg

Koen: I think you are into something here. This thougth has also "flashed" through my mind. The pump feeds the exsess fuel back to the tank and must give some kind of pressure. I have tested the plane on the ground and the fuel consumption is back to normal, one liter of fuel in twenty minutes with half throttle.(no fuel out of vent) So the only way out of the tank, must be through the vent during flight. May be you are right, the combination of a little pressure from pump and the venturi effect. I will certainly look into it. No turbolator because of construction. Will not fit.

germrb

My Feedback: (3)

Straightleg,

The APS 380 fuel pump does not pressurize the fuel tank. The check valve prevents pressure from reaching the tank. The pump make pressure is in a small loop and provide fuel pressure to the carb. The only way to have fuel come out of the vent tube is on a "down line" and hopefully this is a very short time.

mogman

edit.

Jack Diaz

My Feedback: (1)

Hi guys. Great thread.
I am new here, so my question has probably been answered and I overlooked it (thread is looong !!!! LOL)


The problem I am experiencing is that the motor (250, about 30 flights) starts coughing after 5 minutes into the flight. First 5 minutes are awesome.
If I open the H valve, it gets worse. I am afraid to close it further. It is opened 1.5 turns.
Cylinder at 7 oclock is a lot cooler than the others after landing.
Valves, plugs, pump pressure line, etc. are all as per specs.
Prop: Mentz 32/18.
Ground RPM: 4100
Field altitude: 5500ft asl.
Field temperature: 75 deg.
Airplane: Airworld FW-190 1/4 scale
The problem happens with and without the cowling installed.
Cylinders temperature: I will check this week

My question: Have anybody "had experience" with the Turbulator to solve this issue?. I know that in theory it will work, but I will like to know from your results.
Ditto with the electric pump.

Jack

Maxam

My Feedback: (62)

Jack, i have a 215 and I used to have a 150. They both benefited from the turbulator greatly. All cylinders within 10 F of each other and I like the carb further back so it is easier to get to everything. The 150's pulse generator was adequate but not on the 215. The APS pump was a great improvement. It put the carburator into a different "mixture mode" so the midrange has good mixture along with the high and low throttle positions. -Tom

germrb

My Feedback: (3)

Jack,

It sounds like you are running too rich, particularly on the high end. The "missing" is probably the #3 cylinder (7:00 position) dropping out during flight. That is why it is so much cooler at the end of flight. I have had that same experience.

At 5500' normal needle valve settings don't apply. I fly at 4300' and my settings are about 1/4 to 1/2 turn less than settings at sea level.

Also, I would strongly recommend installing an APS 380 fuel pump. It will provide much more reliable fuel delivery and increase your top end performance. The turbulator is a different issue. I would try retuning your engine and installing a fuel pump before considering a turbulator.

Also, see Tom's comments above.

Good luck,

koenvlieg

Jack,

I would close the L valve for +- 1/8 turn and see what happens
are there wet sparks, can you see it at ground level, may-be one valve stops ?

fg

Koen

Jack Diaz

My Feedback: (1)

Thanks a lot Maxam, Bob and Koen.

I have been waiting to try the motor with a leaner setting, but it has been raining heavily everyday. In fact, I just came from the field and couldn't even get out of the car[:@]

Yes, the plugs were wet and with some carbon. Mainly the one at 7 o'clock. I cleaned them and switched the 7 o'clock with number 1 cyl.
Valves are working perfect.
I have been using ELF 2T pure mineral 30/1. I am switching to Motul 800 Off Road (premium oil for motocross racing) 40/1.
My engine has about 25 flights.

I am ordering the pump and turbulator, but will try to tune the motor first before changing anything, as you guys suggested.

As I said, the first five minutes are just awesome performance. Somebody at the field suggested to change the timer to five minutes !!!! LOL.

Thanks again to all of you for your help. Great thread.

I will inform my findings as soon as it stops raining.

Jack

RichardGee

My Feedback: (156)

Jack,
Your problem has all the signs of a fuel starvation issue. The obvious things, like tank lines (no holes) come to mind. Of course as fuel level drops, fuel draw is also a bit more difficult for the carburetor diaphram.
The diaphrams in these carburetors move VERY little, and has been pointed out, the pressure pulses from a 4 stroke are less vigorous than a two stroke, meaning, even LESS vigorous diaphram movement. The diaphram material MUST be very compliant. Additives in some gasolines (ethanol especially) AND some 2 stroke oils will cause some rubbers and plastic derivitives to stiffen - this can happen to the diaphram, making it even less efficient such that anything less than a full fuel tank will be more than it can handle. IF this is the case, the diaphram must be replaced - very easy to do with a standard carburetor kit.

Have you tried locating the fuel tank ABOVE the carburetor? This would prove whether or not you have a fuel draw/pump problem.
Here is another test if you cannot relocate the tank: Try filling the tank just half full, start your engine and see if it runs fine for 5 minutes? If it does, then you likely do not have a fuel draw/pump issue.

Obviously, an external pump WILL solve a diaphram problem, but simply MASK the problem, while a Turbulator will have no positive impact, unless the source of your problems really is a cylinder going rich or lean in flight and dying. But then WHY does the cylinder always re-light and run just fine during the first 5 minutes of the next flight? If the plug is fouling, it will STAY FOULED until you clean it. Simply sitting in the pits for awhile would not make the engine run fine during the first 5 minutes of the next flight.

One other possibility might be your ignition battery... IF the battery is getting hot its internal resistance will go up, dropping its output voltage. Have you cycled your ignition battery under at least a 1C load to guarantee it is not faulty? Is it located right next to the exhaust?

You may end up adding these other devices to your Moki, but I am a firm believer in making sure you have exhausted all possibilities before adding more pieces to the puzzle.

My $0.02

germrb

My Feedback: (3)

Jack,

You didn't mention the 30:1 oil in your original posting. I would have jumped on that immediately. That's way too much oil and is killing the #3 cylinder. I've had the exact same problem late in the flight. Most of us have gone to 50:1 and eliminated the problem. With 25 flights you have enough initial break-in to reduce the oil content.

The fuel pump is still a very good idea, but I agree with Rick that the turbulator would probably not do much for you.

Good luck with the rain, its been raining here for three days.

DENTO

G-DAY RITCHARD
First of all I must point out that I do not know very mutch if any thing about 4stroke RADIALS, On post 1164 page 47 there is some shots of heat distrabution on the cylinders do you think that the turbolator has any bearing on this as I have ordered one for my 250 also the pump,
REGARDS
JOHN

RichardGee

My Feedback: (156)

John,

I have owned and successfully flown model engines from the Cox TD .010 to Seidel, Magnum and Technopower glow radials, to gassers of all sizes and makes (and everything in between, incl. diesels) - almost 40 years inhaling the wonderful aromas of model fuels.

However, I do not claim to be an expert on the Moki radial, so cannot speak to after-market devices designed to improve its performance.

I will leave that to the gents on this forum that have real-world experience with these devices.

Cheers!

Scott Prossen

FINALLY!!! A safe, secure and trustworthy place to send your MOKI when you need some work or just a check up. That place is VOGELSANG AEROSCALE in Chapel Hill North Carolina.
http://www.vogelsang-aeroscale.com/ 919-533-6275 http://www.teamaeroscale.com/

Here's my story:
At Top Gun last month I noticed some oil spattering on the collector ring directly behind the No. 2 and 5 heads indicating a small leak in the head gasket. No cause for great alarm but needed to be attended to nonetheless. It was something I could of done but didn't feel like it. I had heard from Barry (u2fast) owner of twin to my Wildcat, that he had recently sent his engine to VOGELSANG AEROSCALE and was very pleased with the care and service he and his engine received. With that I decided to pull the engine, pack it in the original box and send it off to Dr. Gotz at Vogelsang Aeroscale (VA for short). I thought what the heck, I need some work done and a routine checkup and report would be nice too. Also it provides a perfect opportunity for us to test their abilities and service levels. It's been a while sense I've felt confident and comfortable with a place to send my MOKI's.

The guys received the engine and inventoried everything I sent. Great start! The go to guy in the engine end of the business at VA is Steven. Great guy, loads of knowledge and meticulous as you would want. First thing he does is clean the engine till it appears like new. Then he pulled the heads, all of them, to clean all the carbon build up (see photos of mine) and replaced all the head gaskets. Before he starts replacing parts he called me to tell me what he found and what he thinks should be done. Once you approve a plan of action and rough estimated cost he goes about the rest of the job. He also examines the exposed parts for any abnormalities, cleans the valves , reassembles the engine and replaces the plugs. At that point if there is nothing else wrong with the engine it goes on a test stand for running and fine tuning. This process took him 7 hours from start to finish and at $45/hr it cost $315 for the labor. For me, that was well worth the experience and results. Oh yeah, got the engine back in my hands in a week. Yes a week, not months!

Fed Ex dropped off the package at my front door. I couldn't wait to open it as if I was getting a gift! I couldn't believe how new the engine looked and how professional these guys are with their approach to service and maintenance. My engine only had 50 flights (8.5 to 9 hours run time) or so but it was filthy when it left. See the pictures of it in my hands....like new! Also in the box were my original plugs marked one thru five, the invoice, and best of all was a written full account of what came in and went out and the test run results. Better stuff then I've gotten from anywhere else.

I remounted the engine and immediately saw a 150 rpm increase. I then installed a fuel pump I had and that also added another 70 rpm and made the overall running and starting procedure very easy and smooth. It ran great before and is even better now....purrs like a kitten.

I think I will be sending my engine in for an check up with these guys about every 25 hours of run time (1 to 2 yrs for me). This feels like a wise and worthwhile investment for the MOKI. Same approach I take on my cars. Gotz and Steven involved me from the beginning to end. Their communication is first rate and the care and service level is 5 STAR!

This is to say the US MOKI Distributor is also an excellent choice for working on your engine. They will leave you feeling very satisfied, comfortable and confident! If you have any questions about this don't hesitate to post them here or PM me. So happy that there is a place to go when we need regular service or something more serious.

Thanks Gotz and Steven for a job really well done.

Sincerely,
Scott

germrb

My Feedback: (3)

Ok, Scott

Take a deep breath and try a little decaf.
There is a reason VA is the US distributor, as you just discovered. What else should we expect from professionals. Glad to hear your story. It's a great comfort to know someone in this country really understands these engines.

Take care,

germrb

My Feedback: (3)

G'day John,

I have a turbulator for a 250, but I have not had an opportunity to install it or evaluate its performance. It seems to be in the direction of goodness in terms of fuel mixture distribution. However, I have used the APS 380 fuel pump and it makes a significant difference on both low and high end. In fact, I won't run any of my other radials without it. I am considering installing one on my 3W170BiT2 competition engine.

It is difficult to imagine that a turbulator would make that much additional improvement over the fuel pump. My advice is to invest in the fuel pump first and see if you still have any performance issues.

Good luck,

DENTO

G-DAY Detlef
Sorry to impose but had a look at your profile and it went to Everything radial engines, Yet to get into it,Just a question about the APS pump do you need a turbolater with or without the pump to get the same distrubution of fuel to the cylinders .
REGARDS
JOHN

Maxam

My Feedback: (62)

Scott P and all, My experiences with Vogelsang Aeroscale has been excellent as well. When he recommends a product for improved performance, it does. His communication is timly and appropriate. This is the kind of professionalism i would like to see returning to every day life. Goetz truly wants all of us to enjoy our engines. He must be a happy man. -Tom

JPate147

Regarding Vogelsang - his commitment to his customers does not end with the engines. I bought a kit from him that was missing two small parts, and the manual was written in German. He stood behind the kit and got me the parts, and he took the time to translate the entire instruction manual. Amazing that he could do this, and more amazing that he would do this after the sale. He is very good about returning phone calls and emails, and has always followed through with his promises. I am very impressed with this man and his company.

outacontrol41

My Feedback: (9)

I can vouch for him returning phone calls. I had a chat with him about radial engines and what he offers. I was very impressed with his technical knowledge and with his personal insight of how other brands stack up to the Moki. He wasn't playing salesman...just being honest. I'll be buying a Moki 150 from him when the shippment comes in. If you're reading this, Gotz, thanks for returning my call. More than I can say about other companies in this business...[&:]

Wally

Jack Diaz

My Feedback: (1)

I flew today .... no rain.

Awesome performance !!!!
Didn't have to change the needles settings. They were on the spot.
The only change was using synthetic 50/1 instead of mineral 30/1. Unbelievable.

Thanks a lot guys.

Jack

germrb

My Feedback: (3)

Congratulations Jack!

Aways glad to hear from another satisfied customer.

RichardGee

My Feedback: (156)

So, Jack... Are you saying you changed absolutely NOTHING except your fuel/oil ratio and oil type?
And now your Moki runs great for an entire tank?

Jack Diaz

My Feedback: (1)

Yes Richard.
I played with the H and L needles, but they ended up exactly were they were before.
Checked the fuel system as per your suggestion. It was fine.
Ground RPM was also similar (about 4100).
Cleaned the plugs, but they weren't too dirty either. They were oily though, mainly #3.
Looked at the piston heads from the plug openings, they are like brand new.
Went from Mineral 30/1 to Synthetic 50/1 (Motul 800 Offroad).
I forgot: I added a voltage regulator (5.6v) to the NiMeH 5 cells 2800 mA batt.

Two things:
-Opening the H needle only makes the motor richer for the first 1/4 to 1/2 of a turn from the optimal spot. Thereafter it doesn't seem to have any effect. RPM doesn't go under 3800.
-I let the motor run at full throttle on the ground for about 3 minutes (no cowling). Shut it down, and "immediately" checked the cylinders temperature. They were all between 285 and 295 F. The hottest one was #3 ?????? (7 o'clock from the front).

Flew demanding a lot from the motor. From long full power climbs to prolonged slow flight. Perfect performance. Never a cough.

I still don't believe that it is so sensitive to the oil ratio (and/or oil type) !!!!!

Will fly this week again with the cowling on. Will post the result. (I did fly without the cowling before and didn't improve the coughing).


Regards and thanks

Jack

RichardGee

My Feedback: (156)

Jack,
Thanks so much for the feedback. Your experience proves (to me) that too many guys are adding gadgets that are 'masking' an underlying problem with their fuel/ignition set-up. In your case, it appears that too much of the wrong kind of oil was fouling the plug in cylinder #3, or at least causing it to run too cool. I cannot explain how or why the plug would "recover" just sitting in the pits such that the engine would start and run great for 5 minutes of the next flight, but clearly it has something to do with cylinder temperature and pressure.

There is no doubt that a fuel pump will eliminate the occasional clogged pulse tube as a fuel delivery problem, but if the tube is cleaned and valve train lubricated before every outing, the 'clogged pulse tube' becomes a non-issue.

It seems the Turbolator might be necessary in the 150 Moki radial, but everyone I know running the 215 or 250 has not complained of unequal fuel delivery - again, it could APPEAR to be unequal fuel delivery when you observe a poorly running cylinder, but you proved this was directly related to oil type and quantity.

I am running Yamalube R synthetic 50:1 in ALL my gassers. However, was running it 32:1 on the bench in the Moki for break-in, but will most definitely go with the 50:1 mix for flying. Am just a couple weeks away from maidening the P-47[8D]

germrb

My Feedback: (3)

Jack,

Another piece of information. Don't ever run the engine at full throttle on the ground for that long. You will cook the ignition components inside the engine and eventually soften the rings and loose compression. The maximum cylinder head temperature should be 230 deg F, preferably 220 deg F. Flying without the cowl gives you plenty of cooling, but not on the ground.

Good luck,