Scott Prossen

Moki Owners,

While talking to several Moki Radial owners and trading valuable "Care and Maintenance" tips it was suggested that a thread should be started to help each other out where we can. Not sure this is the right area but I thought it was since most of the Mokis are in Warbirds of various types.

When I bought my first Moki from RCS (a 150cc) I was shocked to find that it came with so little information. A single sheet with a couple of paragraphs explaining the plug and valve gap and the type of gas/oil to use and that was basically it. I had found out that RCS put that in the box as they came from the mfg. with nothing in it at all. Now I have several of these Moki's including a few 400's and I'm learning new tidbits from other guys and their experiences. My hope is that perhaps you will share your care and maintenance tips for all of us to learn from and build a sort of "guide" for ourselves.

Over the course of the last two years I've learned that the chrome item sticking out of the front of the hub just behind the prop is a pump that helps the carburetor ensure the fuels reaches the cylinders smoothly at all RPM's. That pump housing can carefully be removed and cleaned and repacked with grease every so many hours. What I'm not sure of is, what grease and how often??? Also, it is very important that you make sure the tube running from pump to carburetor does not fill up with expelled grease and stop the flow of air pressure to the carb. It can and will cause the engine to stop running usually at mid-range to idle. Take it off and plunge it out and or blow it out and you'll be back and running fine in no time.

I have made it a habit of oiling the top and bottom (one drop) of each rod and the pivot point on each rocker before the first flight of each day of flying.

Also, I keep a record of run time and every 60 to 90 minutes of run time I do some routine maintenance. I clean it to free it of all grime and grit. I check all nuts and bolts and frequently find several that have loosened, mostly the fuel intake feeder tube nuts and the exhaust tube nuts going to the collector ring/muffler. I check all the plugs making sure to clean, gap and replace them just snug not "gorilla" tight. I stripped the threads on a cylinder one time and it was an expensive lesson to learn. I have to remind myself that these are steel plugs going into Aluminum heads. I clean the valve area with brake cleaner and blow it out dry to make sure the valves don't start sticking which has happened to me and finally I check the valve gap to make sure that hasn't changed.

I will add more if I see that others have an interest in the subject. Please post any and all of your experiences with these engines. Hopefully we can come up with lots of good maintenance and care tips.

Thanks,
Scott

77chickenhawk

Im not a owner of a Moki (yet) anyways.. but I have to comend you for starting this thred and its location is perfectly placed.. I'll be reading further[sm=thumbs_up.gif]

Scott Prossen

Hey 77chickenhawk,

Glad you're aboard. I have really enjoyed these engines with no complaints. They have been very reliable for me so far. I hope to bring to light any mystery about the MOKI radail. Just need the input from other owners about their routines and experiences in the care and operation of these engines. Mine have all been real easy to start, run and operate. Not being a mechanical genius, I was hoping there would be more available as far as operational care and maintenance guides. There simply isn't and I want to kind of build one here. We'll see how this goes. Hope it grows and has a lot of activity!


Cheers,
Scott

mk1spitfire

Totally awesome sounding engines. You said you got a few 400's..!!!!!!!!!! Dead envious

Scott Prossen

One for a 40% AMR WACO (UPF7). The other is for a 1:3.5 P-47 I hope to have at the Monster Planes 2010 show in Central Florida. The WACO is half completed and the P47 isn't even started yet. The 47 will start later in the year......I hope.

Scott Prossen

Moki owners,

Anyone out there had the guts to try Amsoil 50: or 100:1 ? I'd like to know if so and how it went. I run the 32:1 YamaLube 2R with normal results. Messy exhaust and well oiled parts.....including some parts I don't want oiled, ha ha ha.

Scott

nine o nine

My Feedback: (1)

Can anyone tell me what the result of running these engines with loose exhaust packing nuts would be. On Scotts suggestion I checked them after having run the engine for several hours and found them all to be barely finger tight. Could that cause uneven running at various throttle posititons......mid-range especially? I'm chasing down this problem with my engine.
Scott.....a 40% Waco? Read the build thread on the 30% on the scale RCU forum. Good stuff there. Especially noteworthy is the stab incidence being too low and the suggested balance point being too far aft. Mitch

butlern

My Feedback: (15)

Great topic Scott.

I just got a 150 a few months ago, and I have not yet fired it, but I have been in contact with a few folks who have lots of experience. A few months ago I started contacting other Moki radial owners so I could gather as much information as possible to properly care for and maintain my motor. Everything you have stated so far is dead-on, but I would also add (based on what I have been told) is that your rocker/pushrod gaps must also not be too great, or the motor will throw a pushrod in flight. It has been suggested to me that they be set at toward the tighter end of the tolerance.

You also suggested that the gland nuts on the exhaust collector ring loosen with time. I have hear that they take a long time to fully seat, and that they should be checked and re-tightened if necessary before each flying session (or after).

What about the ignition? Have you have better luck with 4.8 or 6V? I have a 4200 mAh 4.8V for my motor, as I was worried about zapping the ignition with a fully-charged 6.0V battery. What have you been using and have you experimented?

I have a few more weeks of glassing/panel lines/rivets/paint before I'm ready to fire my 150 on the Avenger I'm building.... but I pretty excited about it, though!

Thanks again for initiating this thread.

Best regards,

Noah

butlern

My Feedback: (15)

One more thing, what about the 26x16 break-in prop for the 150? Did you have good luck with this size? I have also been told that the prop is perfect on the ground but the motor unloads too much in flight (this was quoted by a fellow in Australia with a Moki 150 on a Meister P-47). Just curious if you had similar issues with static versus flying loads on the recommended props.

All the info I get on oil is "use 30:1 Yamalube or Mobile T2, and don't stray from the recommened ratio." But, as you say, it would be interesting to hear from other owners regarding the oil. These are messy beasts, I'm told, and less oil might help with clean-up.

Noah

Scott Prossen

Thanks for the input Noah. That's exactly what we all need. The more we get the more we stand to learn.

I've set my valve clearance at .007" and I have to tug a bit to get the feeler gauge back out......I would say that it was snug. Never had a problem with that setting. Good thing to remember is that the tolerance is in very small measurements and it's important that if you do take rods out for some reason, make sure to put them back in the same place they came from. They wear differently so the clearance will change a bit if you move them around to different positions and don't redo the clearance.

Regarding throwing rods and the 26 x 16 prop for the 150; I flew that prop on a 44lb Yak 11 without any issues from the engine. The prop was great for me. I set up my radio so that when I'm at full throttle I only get about 80% travel and about 4900 RPM on the ground. That way the unloaded RPM doesn't get past the reccommended 5400. It has worked well so far. I have seen and heard of guys throughing rods in flight and I don't know what they do to their engines so I can't say for sure why they have and I have not......yet.

That reminds me (darn), I crashed that plane a while back while practicing for Top Gun and put it in full throttle and nose first. I thank God I was running a Xoar Prop. It was their standard wood prop. No laminated ply or fiber type. The prop broke clean but did not bend the crank shaft at all. Yippee! About a $1000 saved there. Prop strikes can be serious $'s with this engine. Consider your prop type when doing regular practice flights.

Finally, you mentioned the batteries. Good subject there. I've been running NiMh 4 cell 4.8v 4200ma with no issues whatsoever. I've heard guys such as Brian Omeara (sp?) say that some of his run better on 4.8 and some run better on 6.0 I don't get that myself and wonder if simply the manufacturer has used different ignitions over the years. Maybe the engines came from different distributors that requested different voltages??? Who knows but thats what I do and that's all I know about that.

What about the rest of you guys, chime in with your helpful knowledge!

Thanks,
Scott

butlern

My Feedback: (15)

Scott,

that's really curious that some motors (ignitions) run better on 4.8 vs 6.0 (or vice versa). I'm using the same battery as you, 4.8V 4200mAh, so I guess I'll fin out for myself in a few weeks.

Good news on the prop, too. I bought two if those suckers, so they better be suitable for use on my Avenger!

Regards,

Noah

Scott Prossen

Noah,

The Avenger sounds cool. Do you have some pics you might be willing to post? Perhaps a build thread that I missed??? Good luck with the completion and maiden.

Happy Landings,
Scott

Scott Prossen

Hey Mitch,

Good to hear from you. I wonder how much back pressure the collector ring muffler creates. Point being that if there is little to no back pressure than the loose nuts/connection are not causing your mid range problem.

Are you getting fire to all the cylinders with a temp spread of 15 to 20 degrees total between all five heads? Also I have found the valve clearances to be vital for smooth operation. Making sure the valves open and close properly and on time (gap) really affects so much of the smooth operating range of each engine. Do you check the valves to make sure they aren't sticking too. Very easy to do and is part of my regular maintenance. It usually gets taken care of when I clean the valves with the brake cleaner spray can and then blow it off with a compressed air gun.

It's got to be fuel, fire or air.......right? Not sure if I helped at all but maybe a few things to think about.

Scott

butlern

My Feedback: (15)

Hey, Scott.

There is a thread here... I did not initiate the thread, but I have been contributing a fair amount.

It's entitled, "Charlie Kellogg's TBM Avenger Build Thread." Link is here: http://www.rcuniverse.com/forum/m_79...12/key_/tm.htm

That link will take you to page 12, and at the bottom, you can see where I was a few weeks ago. I have not updated the thread in a few weeks, and right now I'm just cutting the fuse for hatches, windows, crew door, etc... But I should get to start the glassing this week. The glassing and panel lines go pretty fast, but the rivets might be the end of me... there are a ton on the Avenger!

Hope to get some paint on her in another month, or so.

Keep up the good work here.

Noah

GaryM

My Feedback: (14)

Great timing on this thread. I just picked up a 150 and was also suprised at how little info was included with the engine. I think this motor will definitely require some type of log book so I dont overlook the care it is going to require.
Mine will be going in a Meister Corsair which I am just about to lay out on the work bench.

GaryM

David Jackson

My Feedback: (15)

Good information to share. What a contrast, I have a $99 Super Tigre two stroke engine that came with a small multi-page booklet, but the Moki 250 I purchased at more than $3800+ didn't come with enough information to make the reading interesting. But I got to tell you, this is one sweet sounding piece of machinery. Like most of you, I have gotten into a routine of checking valve clearance every 40 minutes to one hour running time.

My engine is currently attached to my 40% Yak for break in purposes while I continuing building a 1/4 scale Corsair. I actually starter building the Corsair in 2006 hoping that the price of Moki 250 would drop below $4000. Now that I about 6 months from finishing my Corsair, timing couldn't have been better for TBM to offer the intro prices on the Moki radials. I am using a 4.8 volt battery pack with good result and a 32:1 fuel/oil mixture (Honda HP2 motorcycle racing synthetic oil). I am still working toward getting five gallons of petro through it to reach the break in point.

It would be nice if there were more available airframes (warbirds) for the larger Moki radials (215 and up). But anyway, I look forward to reading more from this thread on the maintenance and care of the Moki radials.[8D]

Scott Prossen

Thanks GaryM and David J,

I hope that this thread will pick up steam as the word gets out. If you know someone with Moki experience, ask them to stop in and give us their input on the matter!

Good night,
Scott

77chickenhawk

agreed.
I also would love to hear a story from the guyz that own a moki that has thrown a rod and why it happened. ( I suspect over reving) I heard top gun had 3 moki failures

Scott Prossen

Hey Chickenhawk,

What I remember from Top Gun was a 250 in a CompArf Corsair threw rods twice. I had suspected the valves were sticking or the gap setting was off??? No way for me to know for sure.

The other instance was a dead stick on a 215 or 250 not sure. What I do recall was that the breather line from the pump to the carb was stopped up with that grease and needed to be cleaned. As I was told, once that was completed it operated just fine.

Neither one of these problems resulted in a catastrophic outcome. Both guys did a great job getting their planes back to front and center just fine. A little damage to one of them on a rough landing and that was it, thank God!

Scott

mick15

I have been running three 215s for four years now and have gained some experience which may benefit some of you guys.

Firstly the factory have modified the cam gears from brass to steel on early engines because the brass ones wear quickly, you can feel the wear at the propeller tip, the lash should be no more than 25mm. Personally I think this wear comes from using grease in the gear housing rendering the lubrication very hit and miss apart from the problems caused to the pulse generator (mistakenly called a pump). Since I replaced the gears in two of my engines I have run 80 grade gear oil in the housing with no more problems.

To top up the housing I remove any one of the lower cylinders cam follower and fill from the pulse generator until oil runs from the follower hole.

A small tip for adjusting valve clearances, rotate the engine until one valve is fully open, and then rotate 360 degrees. Undo the locking nut and gently tighten the screw until it touches the valve, you should feel the pushrod just nip. Back off the screw ONE flat and tighten the nut.


m

Scott Prossen

Good stuff there Mick. Thanks for the catch on the pule generator and all the rest.
I know there's a bunch more for us to learn. If you think of any more........please pour it on!

Scott

G-Pete

Nice to hear you run that engine for four years Mick. The real question how much time you have on that engine? I have a FW190 with a Kroma 50cc in there, the engine is little over 2 years old and the total flight are 24 - that's what I mean with how much time.
24 flights, average 12 minutes - 4.8hrs...practically brand new.

I would be interesting to hear about engines which have 100 hours on it...then we can talk about reliability and consistency in power/performance. Brand new ALL engines run...

mick15

You haven’t read the post properly, but if you require run-time the engine in the Yak54 has about 100 to 130 hours.

http://www.youtube.com/watch?v=nzyQJfkOKtY

m

David Jackson

My Feedback: (15)

Mick15,

Thanks for the information. I guess like the rest interested in this post, I am trying to get the best performance and longevity from my Moki radial without screwing the thing up. So your experience/comments are most welcomed and appreciated. I watched the video of your Yak probably for the tenth time and was amazing at the performance of your plane with radial engine. What is the weight of your plane and which prop (diameter and pitch) are you using?[8D]

Scott Prossen

Mick,

Do you use any air dams between the cylinders in the Yak54? It looks like the top of the heads are blocked from air flow because of the lip of the cowl curls so far around. Any over heating isues in that case???

Many Thanks,
Scott