jfassino

I hope to add smoke system to my Moki 150 in the Beast, any suggestions on where to get the nipple for the 150? Any help appreciated.

Jim

BobH

My Feedback: (2)

Dubro makes a muffler nipple. Maybe you can use that.

germrb

My Feedback: (3)

Well, I finally made it to the field with my WACO and got some flight test data on the exhaust wrap. It certainly wasn't what I was hoping for, but I'm comfortable that I'm going in the right direction. The first big improvement is that it lowered the overall operating temperature by about 40 deg F. I am still working on needle valve settings and have got a ways to go. Since I didn't know where the temperatures were at the field, I slowly richened the top by 1/4 turn and the bottom by 1/2 turn. The #1 cylinder maintained the mean CHT at about 240, while the #3 cylinder started to drop out. In fact, the last flight it droped out completely. Also, I was using 32:1 Yamalube 2R.

The attached charts are from the initial ground tests with the wrap and the first flight tests.

The engine ran very smoothly during all three flights with no indication of roughness, even when the #3 cylinder droped out completely. I am convinced that without instrumentation, there is no way to determine the engine environment until things get way out of hand.

My comclusion is that the remaining temperature adjustments are going to have to come from refined needle valve settings and the eventual incorporation of baffles. Also, I am going to move up to 100L aviation fuel and a 50:1 Klotz oil mixture. I am going to leave the high end at 1 1/2 turns for now and lean the low end to 1 7/8 for starters. The lower oil mixture and higher octane should help the #3 cylinder.

I still think the wrap is in the direction of goodness. I got some IR pyrometer readings of the wrapped ring at the field. They ran as high as 375 deg F, so the internal temperatures were probably 450+. I checked the cowl and spinner temps at the end of each flignt and both ever surprisingly cool. Incidently, the higher exhaust gas temp makes fantastic smoke with no oily residue on the plane.

Later,

Mk23socom

My Feedback: (7)

I'm going with big thumbs up to this!..

TheRickster

My Feedback: (12)

I have run about a gallon through my used 215.

When I got the engine I noticed immediately that #2 cylinder seemed to less compression than the others with #1 being the highest. While running it I noticced #2 coming in and out. I pulled the plugs and found #1 cylinder to have a nice tan color with the rest being very black and #2 being black with the gap closed almost completely. I went ahead and pulled the head and jug off that cylinder to inspect the shape of it since it has obviously been run for a while with intermittent combustion and the ring was glazed badly. Washed the piston and ring with brakeKleen and used a scotchbrite to roughin the cylinder back up some and put it back together. Now #2 is about online with the other cylinders compression wise. I did have some needle setting issues but found that the inlet screen in the carb was dirty and after cleaning now the needles are L:1-1/8 and the H: 1-7/8 and they are typical of a Walbro with the H needle not very sensitive and the L being sensitive and affecting the setting globally. On the bench my heat gun readings are pretty consistent at low to mid throttle settings the CHT runs 185-200F between heads and a quick WOT raises to 198-220F. What is surprising the Jug temps running a steady 50F or so higher than the head temps. All this is run on 40:1 Pennzoil aircooled with 1oz to the gallon seafoam and 1oz gallon Castor bean oil to make it smell better..

Germrb if you have not done so I would pick up a carb kit and replace the diaphragms and the inlet screen just to eliminate any issues. I cannot see how the engine is idling reliably with the L needle out that far[:-].. The Ethanol in the fuel nowdays wreaks havok on the thin flapper checks on the carbs and a replacement of them once a year is not out of the question...

I will know more about the engines operating habits once fitted to the plane but so far it is a gem...

Rick

germrb

My Feedback: (3)

Rick,

Thanks very much for the comments and the data; particularly the needle settings. I agree that it appears that the low valve is the key to proper operation. Being at 4300', my settings should actually a bit lower than yours are in Texas. This will give me a benchmark. I did notice that the richer settings seem to increase the differental between the cylinders. Also, the carb kit replacement is always a good idea. I plan to pull the engine when I get a fuel pump and run through everything.

Thanks again,

P.S. Just talked with Dr. G and the fuel pump is on its way.

JPate147

I have a Moki 250 turning a 28 X 18, 3 blade, on synthetic 32:1 at 4,440 rpm. I am getting ready for the maiden and while checking everything out, I found the top cylinder (12 o'clock) has a valve that is sticking. A slight downward pressure will reseat it, but I don't want to start it if there is a problem.

The motor has two break-in sessions of about 10 minutes each. Mixed rpm runs using the factory settings. The engine transitions quickly and powerfully. No misses or audible problems.

I took the pushrod off the affected valve, and the valve spring seems to be fine. The valve snaps closed as soon as I release the manual pressure from my thumb.

Any help would be greatly appreciated.

Thanks in advance,

JPate

Scott Prossen

Jpate,

My suggestion would be to clean it. Get some carb cleaner from the local automotive (NAPA) store and spray it into the open valve and all around the top/seat. Then blow it off/out if you can with a high pressure air line. That way if it is simply carbon/dirt build up, your problem should be solved. Remember to re-lube the moving parts you just cleaned when done!

Hope it's that simple and I was able to help. About every 4 to 5 hours of actual run time I clean all the valves and have never lost a rod or stuck a valve yet. BTW we run a 30 x 16 3blade down here and seem to keep the RPM a little lower (4100 - 4200) so as not to get the high RPMs. Flying them on a couple of 54 lbs WWII planes.

Good luck to you and let us know your results!

Scott

JPate147

Thanks Scott, I appreciate your advice. I will try your suggestion and let you know how it works. I would prefer a larger prop with less pitch, where do you get yours? My engine is in a Carf Corsair. I am a warbird guy too.

Scott Prossen

JPate, I sent you a PM!

Scott

Mk23socom

My Feedback: (7)

I need my fall work to come and go so I can have the winter to build and play with my 150!!.. i only need to do 6 weeks then I can come home!! Come on baby needs a new pair of shoes!!

germrb

My Feedback: (3)

Rick,

I took your sage advice and reset my needle valves. I ran some ground tests this morning (see attached). Things look pretty good and the engine response was crisp and idle smooth. I finally got my tach sensor working and need to adjust the idle up just a hair. The real proof is going to be in flight. The weather looks promising for next week. The winds blowing about 25 - 35 mph today.

I want to finish this set of data without the fuel pump. That's the only way I can make any judgements about the valve of the pump.

Thanks again for the data,

koenvlieg

hello Jpate,

I think I had the same problem with my 215. A valve that is sticking after 5-6 minutes, but it had nothing to do with the valve. The valve remained open and didn't close. I replaced the short rod inside the engine ( cranckcase) that pushes against the rod that pushes the valve open. If the problem is at something at the cylinderhead, the pushrod would fall out or will break.
So now with the fuel pump and the Kunkel turbulator, the engine runs perfekt.

Hope you understand my explanation

Koen

PS I can recommend you a 29*16 3-blate scale von Sep Luftschrauben, I use a 28*16 for my moki 215 and have a very beautifull sound

JPate147

Thanks for the reply Koen, but I think I found my problem. You were right - it was not the valve sticking open. Before my maiden flight, I was checking the motor for any loose nuts or bolts and found that I could tighten the 10 chrome hex 'cups' at the base of the valve pushrod about a 1/4 turn. That caused the valve to stick when open. I loosened the hex cups and everything appears to be working normally now. There is a small plunger inside the hex cup that holds the pushrod, and that is what was binding. I hope I did not break any seals when I tightened and then loosened the chrome cups. RE: the propellor, I would prefer something in the 30 inch range - perhaps a 30 X 16 ?

koenvlieg

will be good on the 250

bcrc

My Feedback: (19)

I have heard that the igniton module for the Moki radial keeps data that can be downloaded. Does anyone know if this is true? If so, how do I go about downloading and examining it?
Thank you.

Scott Prossen

That's news to me! Would love to see that.

nine o nine

My Feedback: (1)

As I've posted before I recently installed a pump on my 215 and am very happy with it's performance. A couple of situations have cropped up though.
"1...Goetz recommends to wire the pump and ignition through the same harness and to use a transmitter operated switch. That's fine but on one flight a couple of weeks ago the engine shut down during cruise flight. It didn't slow down or stagger...it just shut down as if a switch was thrown. Well.....I went back to manually switching the system. I'm guessing that the electronic switch did it's thing by itself for whatever reason. 8 flights later no problem.
2.....Flying the 5th flight in a row on a hot day the engine started to sag at high throttle (overheating?????). I landed with the engine still running and taxied in. After a suitable cooling off period I tried the engine again and it still wouldn't take full throttle. Called it a day and when I got home I pulled the motor and inspected the carb. I found the inlet side to be full of accumulated grease from when I was using the pulse tube. The screen was very dirty and apparently allowed enough fuel through for low speed running but would not pass enough fuel past 1/2 throttle. Cleaning the carb inlet screen and the pocket under the pulse tube inlet fixed the problem. I'm of the opinion that using the pump enabled the engine to keep running even with the dirty screen. ]
Mitch

koenvlieg

When you use a pump, you have to cut the tube between the carburattor and the crankhouse ! The grease that still come out is what is too much, you just have to clean it
I use emcotec remote control switch with regulated voltage in combination with 2 lipo, a123 and sofar had no single problem with it, it's even more safe

Fly2XS

My Feedback: (65)

Gentlemen,
I dearly love the sound and look of the Moki 250 on the CompARF F4U Corsair and I'd love to start a project myself.

Last week at the Warbirds over the Midwest meet in Fond Du Lac, Wisconsin a friend had some difficulty with his engine and it became available as a rebuild project.
Look at the enclosed pictures and advise as to what you feel I should offer for this engine.
Thanks!

germrb

My Feedback: (3)

$1.85

(It could easily cost $2000+ to rebuild depending on cylinder damage)

JPate147

That is heartbreaking - do you know what happened? I am going to maiden the same set up this weekend, and would like to know if it was preventable?

Thanks in advance,

jerry

Fly2XS

My Feedback: (65)

Jerry,
It was completely avoidable.
The pilot had some difficulty in getting the wings to drop into place before taxiing out.
He took off and flew 3 circuits of the field before the wing folded and dropped into the corn.
It was confirmed that the wing had not been locked. If someone had verified that before take-off, then it would not have happened.

Three of the cylinders were torn from the crankcase.

JPate147

Thanks for sharing, I feel for him. Mine is the fixed wing version, so that is one thing I don't have to worry about. I really appreciate this thread - it has a wealth of great information in it. I retro fitted the APS fuel pump based upon the comments I read here.

koenvlieg

It's bad news, the only positive is that nobody is wounded, he can buy a new one and keep this for spareparts