john v.

hi! i would like to ask some information about RC Airplane''Waco 40%'' with 250 cc MOKI RADIAL 4 Stroke..Its my first kit that i make for more than ayear now.And i need some help..thanks..! c'',)

john v.

Thank you Sir for the info...GOD Bless...c'',)

heinzulrich

Need some info? on my 215 &250 , I use the solo props and I like them because of their adjustability. Unfortunately Solo does not make them for the 400, does any one know who does make adjustable props for the 400???

heinzulrich

My stable, though I would post a picture

77chickenhawk

Nice-

Maxam

My Feedback: (62)

Does anyone have experience with the new 250 7 cylinder model?
To Detlef; Does the 400 run evenly enough to where the turbulator is not needed?
Thanks -Tom

Detlef Kunkel

Tom,
there is not much known about the 400- simply because they are hardly seen somewhere.
I have heard 4 or 5 different 400-seriesengines, and their running behaviour was...hmm...not much differing from the 215 / 250.All known experience from the 2xx engines (Pump, turbulator, cylinder failures, overheating when cooled badly, ignition problems etc etc)may also be true for the 400. Some rune fine, others could be better. I dont know what the pilots had as a setup, so any post from my side is not very objective. The only 400 I ever had in my own hands had blown up in flight, destroying everything but the coollector ring (!). It was operated nearly full throttle all its short life. I guess you should fly it a bit more scale-like, that would be helpful in expanding the engines life :-) The 400 is not a racing engine, it is better used for scale flying I guess.

Maxam

My Feedback: (62)

Detlef, Thanks for your reply. I have carefully listened to 400's on youtube and hear similar results to what you said. The B-25 with the two 400's in Germany is quite impressive but I do hear uneven running in the mid throttle settings. I will stick with the turbulated 215/250 series. My 215 is running evenly without any stutter at all throttle settings and confirmed pyrometer readings have stabilized in the low 190 F range for all cylinders. I have also installed the air filter. My plan is to make the engine last for 10 years minimum. I am using a Fiala 32x18 prop. -Tom

Hinckley Bill

My Feedback: (569)

Love the planes in your stable but really love the shop you have to work with!

heinzulrich

Told the wife one day that I hate weeding, she said "Well then fix it" So I did, week later the concret truck showed up. The rest is history. Should have seen her face when she got back from her vacation.
Yup and I'm still alive.
Heinz

Detlef Kunkel

Like it! :-)

heinzulrich

John, I would think that the recomended 32/12 is for run in or ( break in ) so that you do not have a heavy load for the first little while. Once you have a few tanks thru then you can increase the load ( heavier pitch ) prop. Remember any new engine whether our airplane engine or a new engine in your automobile need time to run in before you realy start working tthat engine.
Heinz

wingstrut

John V, I am no expert but I hope I can save you some grief, A 34x12 prop was recommended to me to use on my 215, after running a tank through the engine I ran it up and tached it at 5100 on the bench. Depending on what airplane you use that engine on it's going to unload in the air, especially in a dive and you will be approaching destruction of that engine.
You said a 32x12, unless these guys are running a different kind of prop, I think you would go well over 6000 which is crazy unless you have 5 or 6 moki's lying around.
I was told to not use anything less than a 32x18 unless I was going to put it in a ww1 aircraft that didn't move very fast regardless of what direction the plane is flying.
Also that engine is best in the low to high 4000 range if you want it to last.
Read Maxam's message above posted 10/16/2012 about his engine running great with a 32x18.
These engines are made to turn big props slowly......................It cost me a hundred dollar prop to find this out, so go with the manufacturers recomendation, I think they know more about this engine than the local hobby shop..............My two cents......Ron

JPate147

For whatever an opinion is worth, I agree with Wingstrut. I have a 32 x 19 on my 2 blade (turns 4070 on the ground) and a 32 x 14, 3 blade on my Corsair (turns 4050 on the ground). Both are Moki 250's. They run great and the performance is outstanding.

wingstrut

JPATE147, Thanks for the comment and info, I think a lot of problems would go away if everyone would run these engines in the RPM's that you listed. These engines do not lack for power.
The instructions that came with my Moki 215 stated that if you were going to bench run this engine, attach it to an immovable object, like a building. I first got a chuckle out of that remark but later found, they weren't kidding....Ha!Ha!

Happy Mokiing..............(sorry got carried away)...............Ron

Lins

Just wondering if anyone knows roughly what s/n a new 215 would be? I might have a line on an older s/n and just curious. Thanks

Detlef Kunkel

Wingstrut,
I totally agree with that comment.
I have no idea why anybody would recommend a 12" pitch prop for a moki on a quick flying airplane. Maybe on e VERY VERY slow biplane, but surely not on a bird with normal to fast speeds.
These are NO fast revving 2-strokes, everything above 5700 in the air is senseless (which you achieve easily with a 32x18!!)
The only thing you do is loose a lot of power in the air and kill the engine on the long run. Nobody drives his Porsche on a german highway in first gear (!)

I had those engines here, more than one, blow up main conrod bearing, totally destroying the entire engine ( everything but the exhaust collector ring was heavily damaged).

I have no idea why people do this to their engines...

heinzulrich

You fellas really have me scratching my head. Why is because I run a 32./12 and I'm not getting those high RPM's . mine read around 4700 on ground and my 250 with a 32/14 reads around 44/4500. I have checked it with different RPM meters and get similar reading's. And yes I have adjusted my carb to best performance. I live  in Canada , could it be that the altitude have something to do with it???

jairaksinen

I'd imagine you have a dead cylinder. Ihave a moki 250 with 2-blade Menz 32x20 and it turns on the ground 4400 and in the air 5750. This was too much so I'm changing to 30x16 3-blade.

I had a loose cylinder once and still it took 4400 rpm in air with four cylinders with the 2-blade menz. All the above is at sea level. I have only a Velocity stack from Troy Built Models, no fuel pumps or turbulators.

My brother lives 600m above sea level and he's Moki 250 takes 4300 with the same 2-blade menz without velocity stack

heinzulrich

My cylinders are firing on all 5, time to check the RPM meter and make certain it is working properly. And yes I tend to agree with you. I'm going to go to the extreem with prop size and try 36/15 and 36/12 on both of those engines and see what the performance is like.

wingstrut

Detlef, They want to hear that screaming engine in a dive, they don't realize what they are doing, the crank and rods may take it occasionally but I believe the weak point is the valve springs they will not handle the high revs, then you have components interfering with each other then BOOM!
[size=3] The valve springs have not only to return the valve to its seat but return the pushrod rocker arm and lifter back to it's original location.
That is asking a lot from such a tiny spring changing direction a hundred times a second.
And without an oil pump to supply lubricant to all the moving parts, you guys need to slow them down. I'm suprised this engine lasts any time at all.

Detlef, I like the smooth even rumble the engine makes on half throttle, I cringe when I have to open it up. I could sit around for an hour and listen to the engine idle, but that would overheat it.

I Love Moki's what a fine piece of workmanship, the only drawback is the coils that are inside the rear of the engine, they didn't think that one out.
I will be quiet now..............Thanks for all the info fellas, that really helps us to understand this machinery.

Sincerely, Ron........(wingstrut)

Maxam

My Feedback: (62)

My Moki is serial #1106 and was purchased about 2 months ago from Goetz Vogelsang. Goetz was emphatic that I use a 32x18 or 32x19 on my 215. After much flying (around 50 ten min. flights) I am getting 4400 rpm on the ground with the Fiala 32x18! The 32# yak 55SP now has strong vertical to potential out of sight! zowey! I began the break in process at 40% to one Interceptor (Amsoil). I have settled on 44% to one with nice dry spark plugs with correct brown deposit. There is no deposit on the piston surfaces. Cylinder temps seem to have leveled at 185 F all within 10F of each other. I do use 2 oz of seafoam/ 2 gal of gas from 92 octane phillips 66. Fuel pumped and turbulated. Important note! Full throttle butterfly position on the carb is slightly less than 3/4 open. Makes the Walbro function ideally with correct mixture in the mid throttle position. This was a valuable suggestion from the Moki experts in Germany. The only problem with the 32x18 is a low idle is necessary to slow the plane down on landing. -Tom

wingstrut

Tom, That was a lot of information that everyone needs to heed, especially about the 3/4 throttle opening.
Thank you for letting us know about that one and pointing out about the high pitch props......................Ron

Jaketab

My Feedback: (2)

Maxam,

Thanks for the note about the throttle position. The last 1/4 opening of the throttle butterfly does very little in rpm gain.
I've never been able to smooth out the mid range of my 250. I assume this applies to the high side needle.
I'll try to re-tune at 3/4 throttle this weekend and report back.

On another note - I read about temps below the 200F mark. My temps always seem to be in the 205F - 225F range as measured with a laser temp gun.
What am I doing wrong ?????

J Tab

P.S. Max rpm on my 250 with a 32 x 18 SEP is 4460 on the ground.

Maxam

My Feedback: (62)

J. Are all 5 cylinders the same temp or close? Think about this; you are cooling a 50cc cylinder, not a 43cc cylinder both with the same surface area. More heat to dissipate. My plane has 46 cowl louvers, a huge canister tunnel moving a lot of air as well as a hidden cut-out in the oil cooler of the cowl. My engine even without baffles is getting a lot of cooling air. Finally maybe a SEP 32x18 takes more power to turn than the same size Fiala. There are great differences between props of different manufacture even with the same size. An APC 10x6 vs a Master airscrew 10x6 has a massive difference in power to turn the same RPM!!! -Tom

Both needles must be checked. Another point from the Germans; The low speed needle will greatly help the midrange if it is not too rich. A rich low speed needle will give you a very low idle rpm of 400(!) but will get quite rich quickly as you throttle from low idle to high idle to 1/4 throttle.