Jim Cattanach

My Emcotec APS electric fuel pump arrived from Germany. I fitted it at the weekend & went flying today. The Moki150 is installed in my CY models Bearcat (same as Easytiger).
On previous flight attempts, the engine would die immediately after takeoff. What a difference with the pump fitted. Had six perfect flights. The engine never missed a beat. No problems with any cylinder dropping out.
The Bearcat is like a trainer. I moved the C of G one inch further back than the instructions say, as it has been reported nose heavy at the suggested setting. With flaps, it lands as slow as a high wing trainer. No sign of dropping a wing.

Der Goetz

My Feedback: (9)

I had one of those China ARFs, what a waste. The model is now a decorative piece in my litttle sons room.

On the other hand, the Airworld GeeBeeR3 flies absolutely fanstastic as they did their homework. You get what you pay for, as always.

wingstrut

Jim, I'm glad you got your problem with the fuel fixed, All moki's should come with an electric pump. OH WELL.
As I said before, I saw that Bearcat fly and it slowed way down and seemed to handle like a dream, I am glad you have it all worked out and the combination is what you wanted.
Good luck and may you have many successful flights............Ron

I am ordering my electric pump for my Moki from Dr. Vogelsang after Top Gun.

Jim Cattanach

Cheers Ron. You are right. All Moki radials should come with the electric fuel pump. The investment in airframe, flight pack & engine is to much to risk on the suspect pulse generator.
Hope you have success with your Moki/pump.

jairaksinen

I just run a new moki 250 in a testbench. While revving up I noticed moderate shaking at around 1400 rpm. There was another shake at higher rpm but did not record the rpm. The prop was menz 32x18 and it was in perfect balance. Is this shaking normal for this engine? The max RPM was about 4600@ 600 ASL, sounds about right? The engine was run out of the box with 4% synthetic oil and 98 octane gasoline after 3 litres of break in.

Jim Cattanach

I am only using half that amount of oil. It could be that one of the spark plugs is oiling up & not firing (probably number three), especially if you have a rich mixture setting..

Der Goetz

My Feedback: (9)

What is it with these high rpm lately? You are not the first at 45, 46 the last few few weeks.
That is fantastic and I HIGHLY recommend getting a 32*19 or even 32*20. Right now you are prone to unload in the air on a mere 18 pitch. Or go 39*18 / 40*18, if you can find one.
But should you be planning on putting the Moki on a warbird, please do the engine the favour and get a 19/20 pitch.

Anyways, sounds great. Shaking is to be expected as any engine will have a "resonance" rpm band. Just check your small 70 OS and Saitos, same deal. And your teststand will have a harmonic frequency of its own on top of things.
-Götz

jairaksinen

Well the high RPMs comes from the manufacturers test rpm with menz 32x18 propeller, the propeller is the same that they use so I want to confirm that the engine is performing as it should because to prone to missfire on the #3 cylinder. The #3 was noted to be colder than the other ones, but the #1 not allways being the hottest one. #2 was sometimes the hottest one. I will give it a go with a menz 32x20 on a another moki to see what is does. And it will be on a warbird. I'm hoping to find a prop that would give around 3600-4000 static rpm, I may have to go 3 blade. I had a moki before with a 30" 3 blade solo prop.

A 40x18 would give a somewhat impressive look I'd say,.
Your really sure it can handle it.???have you tried it? @ what RPM?

But good to know that the shaking is to be expected as I figured to be a resonance.

I will be trying to baffle only the #1 cylinder, and thus half of the neighbouring ones to see if I can get the temps to same region. I will go for as aerodynamic baffles as can to see if makes a differcence. I will also try the carb intake unit from TBM a purchaced for the last moki.

mick15

FYI I'm running a 32x14 three blade on my La7.

m

Jim Cattanach

I have about 12 flights on my Moki 150 with the electric pump & the engine runs very well now. I am using Menz s two blade 26 x 16 props. On the ground, I am getting 5,300 rpm. In level flight, my Bearcat is getting full rpm. In a climb, the rpm falls off very quickly & it is not possible to do a loop.
It feels like the engine is over propped. Is anyone using a prop with less pitch?

Forgot to mention. Weight of model is 33lbs.

Mk23socom

My Feedback: (7)

Holy crap, 5300 on the ground!?.. that sounds to me like it is UNDERpropped.. I wouldn't want that much RPM on the ground.. I would imagine that is a thrown pushrod waiting to happen..

Jim Cattanach

The factory test data sheet shows 5,200 rpm on a 26x16 prop & that was when new. You cannot over rev these engines, they have a rev limiter in the ignition system, although I do not know what the rpm limit it is set at.

mick15

I think that is a bold assumption Jim. (Where is the evidence for your statement?).

Although I believe the valve gear would prove to be the rev limiter, once it had disposed of most of its pushrods! LOL.

m

Jim Cattanach

No assumption Mick . See under ignition system.

http://www.moki.co.uk/moki.htm

Jaketab

My Feedback: (2)

Update,

To keep all advised, I had a problem (posted previous) with #4 cylinder not firing on my yet to be air tested Moki 250. After some diagnosis with help of Bigdammodels, (Bill) the problem was either the #4 coil, wire, or resistor. Last week I replaced the #4 coil with a new one received from Airworld-Germany. Transit time was about 2 ½ weeks with overall cost of 44 Euro or 65 US. Over half the cost was shipping.

I tested the plugs for spark with plugs installed in the boots outside the engine. Alas - #4 and all coils are arching electricity. It does appear that coils may fail, whether it be the coil itself, plug wire, or resistor in the boot. After reassembly and test run, #4 cylinder is back on track.

When I re-assembled the motor, I used Permatex Hylomar Universal Blue to seal the O-Ring in the intake tube. I also used it to coat both the carb intake gaskets. Previous to the repair, the motor before could not be tuned rich on the high needle.

I believe the cause was air leaking into the intake tube at higher rpm’s. Tuning the high needle now causes the engine to be responsive to both lean and rich settings. The high needle adjustment is now very responsive.

Moral of the story - if you can’t get your Moki to run rich on the high needle adjustment, check the carb gaskets to make sure you are not pulling in air at higher rpm’s.

mick15

OK fair enough.

m

Mk23socom

My Feedback: (7)

I still would be worried about tossing pushrods, electronic rev limiter or not..

goneflyin2002

Mick, it's true!
I've been into the rev limiter during a dive with my Boomerang/150 (with my policeman friend holding the radar gun) I heard the distinct miss of the rev limiter come into play. I immediately backed off the throttle to preserve the investment. It sounds exactly like the rev limiter I used to have in my muscle cars (with an MSD ignition).
No question!
And my pushrods stayed in! LOL
What a great engine.
Love it.
BTW, he clocked it at 218 km/h[8D]

Don

stivvy

Hi Guys,

Hope someone can help.

I have a used MOKI 215cc radial, complete with APS 250A1 electric pump.

As I am new to radials can anyone help with a user/operation manual for the MOKI and how to best connect the APS pump - I guess the pump runs at full power and the carb takes what it wants ie - no return line to the tank ??

Thanks

Steve D (UK)

Jaketab

My Feedback: (2)

Stivvy,

I have the older 2 line version of the APS 380. This is my plumbing set up regulated at 5.3v shared with the optic ignition cut off.
This way you always have continous feed returning to the tank and don't have to worry about priming if you empty the tank.

Jaketab

Brian Rawcliffe

Hi Mick
It's been a while since we flew in the same slot, maybe Cosford this year. As regards the speed limiter on the Moki it happened to me last August at the Elvington Show, but I know the reason why.
I have always used on my 150cc a menz 28"x12" 2 blade propeller, unfortunately after my second flight I was pushing the model back to the pits area and clipped a 1/4 of an inch off one tip. My spare 28" x 12" was a ZDZ propeller a type I had not used before, and on the very next flight when doing a low pass ( at full bore of course) the rev limiter kicked in for at most less than a second.
Checking the propeller after the show the ZDZ had a slightly finer pitch and leading edge. After reverting back to the Menz the problem has gone away.
I f anyone is interested you can see that flight and clearly hear the rev limiter activating. Go on to U-Tube and type in LMA ELVINGTON 2011 TEMPEST 2.
Regarding my 150cc Radial which I obtained off Stuart Mackay in 2007, it is still 100% standard with no modifications whatsosever. Other than periodically checking the tappets, making sure that the festo tube is clear, and tightening the collector gland nuts, I never touch it. As the saying goes, if it ain't broke don't fix it.
I have been flying the Tempest for 4 years at LMA shows and I have never had a cylinder go out, or loss of RPM's , or an engine failure of any type, I just choke it, flick it and it starts and fly it. I have always used a fuel mix of 40-1, the oil being Bel-Ray H1R 2 stroke synthetic racing oil. Since setting the jets in 2008, I have never had to readjust them.
The model weight is 42lbs and if required you can do loops as big as you want , it's just fantastic.
P.S Hello to Scott & Greg who I met at Cosford in 2010 when they were visiting the UK. Best wishes to all radial pilots. Brian
Steve D give me a call on 01484 713136 regarding Moki instructions after all we only live 12 miles apart.

mick15

Great to hear from you Brian, yes that has been pointed out in a previous post. My scientism was born of hearing the way Ali screams the nuts off his 250 I never heard his go into rev limit!

Will not be doing Cosford this year, maybe next, busy building another Sea Fury.

m

stivvy

Hi Jaketab,

Thanks for the details of the APS pump.

Had a look under the cover of the APS FGP/250 pump and it has the by-pass arrangement as your sketch so all should be well.

Thanks again.

Steve D

Scott Prossen

Hey Brian,

Good to see you and the Tempest. She is a fine model and you flew the paint off her. Love to hear of your experience with the MOKI. I have a 150 that must be cut from the same lot. It has run since day one just as you described and nearly zero troubles with it. Just standard maintenence as you mentioned. Well back to work I must go! Take care my friend. Say hello to all the boys Greg and I met when we visited you.

Happy Landings,
Scott

Aircraft Modelers Research Inc

My Feedback: (2)

Hello everyone,

hope you enjoy your radial engine as much we do, 180cc work very well, hope to get the 250 7 cylinder next week to test our Waco 33%