RE: MOKI RADIAL Care and Maintenence
 

With regard to air leaks. I found my 250 was pulling air in from the carb intake gaskets on each side of the spacer block.
This only occurred at higher rpm's. I used Permatex Hylomar Universal Blue to seal the gaskets. It's fuel proof.

The engine tuned much better after the fix.

Jaketab

RE: MOKI RADIAL Care and Maintenence
 

I'm going to try and chase down the airleak situation as I'm sure that's the cause of my problem. It'll be a while though as I'm flat on my back for a few days......damn muscle spasms. Mitch

RE: MOKI RADIAL Care and Maintenence
 

That is not an air problem, it's more likely to be fuel starvation. I suggest you remove and strip the carb sound like a restriction on the H needle port.

m

RE: MOKI RADIAL Care and Maintenence
 

2 carbs...one stripped and cleaned, the other brand new out of the box...exactly the same result. Mitch

RE: MOKI RADIAL Care and Maintenence
 

Hello Gents,

I have found this thread very informative and it has taught me a lot about my Moki S250.

Here is a YouTube Link to the second flight on my 1/4 Scale Fw 190A-7.

https://www.youtube.com/watch?v=medzQ52I8_U

The model is an Airworld Kit. Dry Weight is 24.8 Kg. I am still running-in the motor so you will notice she is fairly rich on the low end, I am NOT using a Turbulator but am using the Emcotec APS PowerFuel 380 with fantastic results. I have 2 x 2100 Li-Po's on an Emcotec DPSI which runs my ignition and fuel pump.

The engine is baffled and performs flawlessly during the summer months in Dubai. Although we are at Sea Level when I flew this morning the ambient temperature was 38C / 100F and the pressure is very low, resulting in a High Density Altitude (3,000 feet).

Due to the strong crosswind I was going to do a "Wheeler Landing" but bounced a little, so I chickened out and ended up doing a three pointer.

The video is a little jerky, I will get around to doing a better one some day.

Regards,

Darryl Tarr

(Dubai)

RE: MOKI RADIAL Care and Maintenence
 

Darryl,

Very nice. Wish I had your attention to detail.
Maidened my Airworld Gee Bee R3 Air Racer Special last week. My first radial engine plane. Powered by Moki 250 and fuel pump. Temp was 95 F that day. Wingspang 118" and weight appx 54.5 lbs.

Once trimmed, it flys well without a gyro. I was lucky to get back ground in one piece considering I have not flown in over 1 year.
The 1st aborted landing attempt shows how easily the plane can stall.

It has a 50oz fuel tank. Good for 15 minute flights with a little reserve.

I did not want to chance the motor overheating. Installed 4 aluminum louver vents in the cowl.
One on top and 3 on the bottom. When you stop the motor, the heat builds up in the cowl. Needs a place to escape.

http://www.youtube.com/watch?v=xmDfL...ature=youtu.be

J Tab

RE: MOKI RADIAL Care and Maintenence
 

Awesome job Jaketab! I love that plane and paint scheme. The Moki is always my fave!
Congrats on the maiden and the work on the plane. Definately one I wish I had.

Wish you 10,000 happy landings,

Scott

RE: MOKI RADIAL Care and Maintenence
 

Nice video and plane. Sure sounds like you need more pitch in the prop. The RPM's sounded like it was revving on the red line :o)

RE: MOKI RADIAL Care and Maintenence
 

Thanks,

The Gee Bee R3 with the 250 is running a Beila 32 x 18.

Jaketab

RE: MOKI RADIAL Care and Maintenence
 

Last weekend my S250 was flipped over in the desert and got a lot of dirt on the motor.

The motor was not running when it got dusted with all thatdirt.

Do you guys think Ishould pull the push rods out to clean the sockets?

Anything else that you would recommend based on this event?

Thanks!

Tom
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RE: MOKI RADIAL Care and Maintenence
 

Yes, always a good idea to clean pushrods and the soket that they sit in, and then relubricate . Rather be safe then sorry afterwards.
Heinz

RE: MOKI RADIAL Care and Maintenence
 

Hello Jake,

Awesome Gee Bee R3, WELL DONE. I have always admired this aircraft and yours looks fantastic. You guys also have a really nice flying field.

I think "77chickenhawk" was commenting on my RPM being on the RED LINE (not yours).

Currently I am running a FIALA custom made 28 x 18 prop (which is a little under-propped, I know), but I don't want to over torque the crankshaft during the break-in process, also I am NOT using full power at any stage to keep the RPM down as the Static RPM is 4,800.

I have just ordered the Functional Scale Spinner and FAN from Vailly Aviation to get more airflow into the cowl as very soon I will be putting on the BIELA 3-Blade Scale 32 x 16 Prop, especially designed for the Fw 190.

Cheers,

Darryl

RE: MOKI RADIAL Care and Maintenence
 

Darryl,

That 32 x 16 3-blade may work on my R3. Weight is about the same as your FW 190.
If you get a chance for another video, would like to see (and hear) the sound of the 3 bland on your plane.
It's all about the sound.

Jaketab

RE: MOKI RADIAL Care and Maintenence
 

Hi Jake,

Quick question:

Valve Adjustment Screws (or Tappet Screws). Where did you get some spare ones? I need like 20 as I would like to replace mine and keep some for spare.

It's a pity these screws are not like the O.S. ones where you can fit an Allen Key onto the adjustment end, I find the screw slot weakens the screw. I have done thousands of Google searches for Moki Tappet Screws / Valve Adjusting Screws but came up with NOTHING.

Regards,

Darryl

RE: MOKI RADIAL Care and Maintenence
 

Darryl,

AMR in Canada is out and expects to be getting Moki parts in about 2 weeks. Just sent TBM an email. They only sell rocker arm sets at $45 US per set. I have not checked with Vogelsang yet. It has been suggested to me to make my own from 3mm allen head screws. One person I spoke with say's he just drills out the hex part and make certain the bottom is rounded to accept the pushrod end.

Micro Fasteners is my source for hardward and screws. http://www.microfasteners.com/

I've thought about getting a 1/8" dia. ball end carbide burr from McMaster-Carr and trying to make my own.
Drill and tap out 3mm threads in a block of wood to hold the screws while drilling.
Keep them cool with water while drilling. Do you think that will work??????

http://www.mcmaster.com/#rotary-deburring-tools/=hvjdxh

Someone may know of a better tool to fabricate these with ?????

Any help appreciated.

Jaketab

RE: MOKI RADIAL Care and Maintenence
 

Bent Pushrod ????

This past Saturday I had (2) - 12 minute flights on my Moki 250. Gave it a pretty good work out with temps around 85 F.
Prior to the flights, all valve gaps were adjusted to .0025" or .063 mm

This evening I discovered that #4 exhaust pushrod was bent.
The #4 exhaust valve appears to move free when manually depressed. I don't know if some sticking occurred.
I'm running 90 octane ethanol free gas with Sthil Ultra HP at 50/1.

Can someone in the know please tell me what are the possible causes of a bent exhaust pushrod, and
what if any damage upon the engine may have happened?????

Is it necessary to periodically decarbon the valves with Seafoam or similar type product ??????

On the last flight, the engine appeared to be running normally.

Thanks - Jaketab

RE: MOKI RADIAL Care and Maintenence
 

Turbolator Report on 150. 350 rpm gain on top end. it hits alot harder at idle, every one couldnt believe how different the idle was. acceleration is smoother and cleaner. but I have the old 150, pre november 09. I'm finally seeing the numbers that everyone else is seeing with the newer engines.

RE: MOKI RADIAL Care and Maintenence
 

Yay for Jeff! Finally happy with his Moki. Didn't think it would ever happen for you buddy......so glad!

Happy Landings,
Scott

RE: MOKI RADIAL Care and Maintenence
 

Jaketab, Something interfered with the natural function of the valve train, here is a list
valve springs weak from overheating not allowing the valve to return to its seat fast enough and the piston contacting the valve.
valve lifter stuck
valve stuck
Valve seat coming loose.
overrevving the engine

I don't have a breakdown of the moki engine so I can't tell if valve and piston contact is even possible, but if it is you need to check the compression on that cyl to see if any damage to the valve or piston has happened.
You need to remove all the other spark plugs to make it easier to check that one cyl.
Turn the engine over slowly bringing that cyl up on the compression stroke and listen, you may be able to hear the valve leaking air into the exhaust manifold.
If you have compression and it seems to hold then you may have luck on your side.
Obviously if you have a leak and can't hold compression on that cyl. then it needs to come apart.
If the valve has contacted the piston it could have pinched the ring in the ring land and this would soon destroy the cyl. if not replaced.
And obviously the valve may be bent.

If everything checks out alright, I don't know how fast you are turning this engine, but everytime I see a Moki on a WWII warbird they are screaming across the sky.
and I just cringe waiting for the cylinders to leave the crankcase...............These engines turn big props at low rpm's, there are too many moving parts to be turning these things like two strokes.
Sorry for the extra comments, but we need to run these engines in the correct range, I put all the blame on the manufacturer for the poor support and lack of operating instructions.

As long as you are using that mixture and the cyls. are firing and the temp is up I don't think you have a carbon problem.

Good Luck, .........Ron

Let us know what you find.

RE: MOKI RADIAL Care and Maintenence
 

LOL! thanks Scott! It's only taken a complete tear down, polishing valve stems and guides, 3 ignition sensors at 115$ bucks a pop, 30 spark plugs, and finally a turbolator:D:D:D. So yes I think I'm finally happy:) I was getting 5400 yesterday with absolutely no missing.

RE: MOKI RADIAL Care and Maintenence
 

Hi Jake,

Thanks for the information, actually Airworld Modellbau have just sent me 20 tappet screws in an envelope.

My valve clearance is set to 0.05mm BUT I do clean them (valves, rods, tappets) after a days flying - which is usually two flights. You will be surprised how much carbon build up there is, admittedly my motor is NEW and set a little rich, but several squirts of fuel and a good scrub with an old toothbrush cleans them well, then a generous dose of WD-40.

Actually a better lubricating product is the SONAX Formula 1 Performance (Multi-Functional Spray Oil).

Now I am a little nervous, perhaps my valve clearance should be higher (0.08mm).

Regards,

Darryl

RE: MOKI RADIAL Care and Maintenence
 

Darryl and Ron,

Thanks for replies. Saturday was the first time running since gapping the valves at .063 mm. Possibly, I set the #4 exhaust too tight.
I hope the push rod is the weak link by design to prevent other damage.
Some down lines may have over-revved the engine.

I'll check all suggestions. One extra pushrod came with the engine so I'm still in business.

One other change to the engine is a sqeaking sound that is noticeable at idle rpm.
Additionally - the pulse tube is cut open - but I have to date never seen any grease leaking from the tube or pulse pump ?????

Sea Foam is a cleaner/lubricant that I have used in past to de-carbon and de-grease internally. Saturating through the spark plug hole and letting it soak overnight brings out a lot of gunk. The manufacturer recommends up to 2 oz per gallon to keep engine from carbon build up.

Thanks - Jaketab

RE: MOKI RADIAL Care and Maintenence
 

Jake,
If you have the same "squeaking" sound as I did, the rocker arms are the cause. Although I heard the squeaking sound only when I rotated the prop my hand (several revolutions), yours may be more severe. I lubricated the rocker arms with Tri Flow (Ace Hardware and recommended by Goetz) and the squeaking sounds go away. Goetz stated that before each run, lube the rocker arms.
Hope this helps,
Tim

RE: MOKI RADIAL Care and Maintenence
 

In regards to lubrication, I rotate the crank until a cyl is at top center on compression and both valves are closed, then I press down on the valve end of the rocker and remove the pushrod then I can completely lube both ends of the pushrod and work the rocker back and forth to distribute the oil, I also lube the lifters and valve stem.
Then I proceed to do that to the additional cyls until I get them all.
I think I will go with the tri-flow that sounds a lot easier and I will look into the Sea Foam to help keep the carbon away...................Thanks Jake, Tim and Daryll

RE: MOKI RADIAL Care and Maintenence
 

@ all: if you hear some squeaking sound by turning the engine by hand, check carefully that you dont have dry running tappets on your cam drum. I ve had that with customer engines more than just once (!!)