UMS Gas Radial Engine Enthusiasts Rabbit Hole
 

Here goes Tom. Thanks for helping me start the new thread.
Aaron (Hyjinx)
My new UMS 125 from CH ignitions in Florida USA.
https://cimg6.ibsrv.net/gimg/www.rcu...3dadfcee2d.jpg
Brand new UMS 125 in a new to me Waco 60 Arf. Un started as of yet 4/18/22.
Thanks to anyone who is interested in sharing info on the current design UMS Gas Radials....

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Well done Aaron!
 

I hope this thread comes alive.
The UMS 5-100; I now have 15 8 oz tanks of 40;1 redline ethanol free gas/ oil with 2 oz of Sea foam/ gallon. Nearly perfect carburation through the entire range from 600 rpm to 4500 turning a Xoar 25x12 prop. True horsepower is 4.65. Think of a DA50 with belt reduction. A Moki 215 is 9.5 Hp at 4000 rpm...This engine is very easy to start. The mid throttle is slightly lean but a lightly rich setting at idle takes care of that. No blubber rich areas through the throttle range. All cylinders run evenly!!! My UMS 5-55 and 5-100 do run rather hot at 230 F. The APS power fuel fuel pump is required (5-100).

I am running a UMS 5-100 on a 1/5th scale Ziroli AT-6 Texan although I haven't done the maiden yet. Long story about that but the maiden probably won't happen till the end of the year. As Tom has stated, the 5-100 is an easy to start, smooth running engine. I am turning a semi-scale Biela 25x14, turning 4400rpm's.

Seems RCU requires a member to have 10 posts before pictures/URL's can be uploaded, so let's see how this goes. This should be post #10 for me.

Picture of the Ziroli AT-6 with a UMS 100-5 up front.
https://cimg3.ibsrv.net/gimg/www.rcu...6a3ee432cb.jpg
Ziroli 1/5 scale AT-6 Texan.

Super cool Tom. Really looking forward to this flying season. I too have a Moki, yet un-started new 250 -7. Dr G recommended Amsoil Dominator for it. I have it so I think I will start out with it in the new UMS. Adrian recommended a APS for the 125. I bought in. I am using Spectrum equipment now from Frsky. Checking into sensor options.

That makes my knees shake! Absolutely beautiful Sir!

Uploading pictures and video has been harder than landing the Texan for me lol.

Hi Tom,
Did you have to use an adapter to mount the Saito carb on your 5-55.

Here is a picture of the business end on my 1/3 scale BUSA PT-17. UMS 260-7, that has performed flawlessly for 30+ flights now.
https://cimg9.ibsrv.net/gimg/www.rcu...e8fb033f73.jpg

Do you watch temperature on cowled and open air set ups? Seeing both, I wonder if the Texan rums hotter? Assuming the same oil mix and octane rating and non ethanol gas blends....

I no longer monitor head temps on the 260 since I have a lot of flights on her. Since I fly Spektrum I am using their temperature sensor to keep an eye on the 100 in the AT-6. Not having flown the plane yet, I don't know what the readings will be although on the test stand average was 170°

EDIT: Depending on the head temps of the 100-5, I may have to construct some sort of engine baffle. This would be a new undertaking for me so any and all suggestions/recommendations will be appreciated. Also, I used Amsoil Dominator in my radials at a 50:1 ratio and so far have not encountered any problems. I lube everything on the first flight of the day with gear lube.

GI Jon, yes I did. I hope the O-rings last with gasoline. Neat little engine. (5-55)
One other thing I like about the 5-100, still uses the little glow size spark plugs. I talked to Adrian about the thick R-Excel spark wires that are cumbersome especially on the smaller engines. He said the thinner wires do not work well with a hot spark.
To anyone interested. I have completed my Schlundt 46% Bowers Fly Baby using a Moki 257.
Nice Texan and Stearman and Waco!

-Tom
PS Great title for the thread!

Yeah Tom. I'll probably want to install the Saito carb as well.

Tom, By chance are there any pictures of the Fly Baby?? Just have to see the 257 on the front end of that Baby!!

Gary

YES! What a beauty.:)

Fly Baby
 

About to install windshield.
https://cimg1.ibsrv.net/gimg/www.rcu...d9a1a8e5f8.jpg
https://cimg2.ibsrv.net/gimg/www.rcu...09f5ef017d.jpg

Thanks. Good help. I am going to construct the baffle of a 12x12 aluminum flashing blank from the home dope show. Aka Home Depot lol. I'll photo doc and post.

Place your 5-100 on a sheet of paper with a flashlight shining straight down. The shadow will be your template. Place the flashlight as high as possible so the image has the least enlargement. -Tom

Thanks for the suggestion Tom. I wish I would have asked this question before mounting the engine on the plane!!! Oh well, it'll give me something to do the next time it rains!!! Thanks for posting pictures of your "Baby". I'll best she flys like a dream.

UMS Radials…
 

I’m on my second UMS made radial, this one the 5-150 going on the TopRCModel P-47 96”. Plan on flying a SEP 23X14X4.

https://live.staticflickr.com/65535/...d93e412e13.jpg

https://live.staticflickr.com/65535/...3205ca898f.jpg

My UMS engine is the Tomahawk branded “Blackstar” 5-250 which I picked up bundled with a 1/3 scale Tomahawk Wilga. My experience with this engine along with Adrain’s support shifted me to this brand.

https://live.staticflickr.com/65535/...47146f99ae.jpg

https://live.staticflickr.com/65535/...ee9320818e.jpg

I run them both, as well as my (2) Moki 250’s & (1) Moki 215 on the APS fuel pump. They run strong, sound great and with the exception of the pump, require no changes out of the box. My Moki’s required switching ignitions, disconnecting the fuel pulse pump and don’t support RPM telemetry.

Cheers

UMS manufactured “Black Star” 5-250 video
 

Here’s a video of the 5-250


Cheers

GREAT looking planes, Mark, and thanks for posting a video of your Wilga. Do you still have your Stearman??

Gary

Thanks Gary, and yes still have the big Stearman w/Moki S215. Still have yours? Have you picked up a UMS radial???

Cheers

Hey MarkspThe Tomahawk is the next purchase for me. I haven't been able to come up with a 180 Moki which was (is) my hope. I have one more airframe to finish out my Big Four.
Looking at a non Chinese Arf of a Bucker Jugenmeister single seat. The cz is Chinese unfortunately, so it's ruled out at this point. Please continue to post your experience with the UMS Tomahawk. Thanks Aaron-

Yes, still have the PT-17 (see post #11 above) and sold the Moki to Tom, picking up a UMS 260 in it's place. Definitely NOTHING wrong with the Moki; it just didn't look scale to me and I am way anal in that respect. Good to see you on this threat and letting us know what you are up to. Happy flying season ahead!!!

Hey OK! I am sure you put 2 and 2 together. That is your 257 on my new Fly Baby! -Tom

A review of the 5-55
 

So I got the 5-55 from Adrian 'cause it is cute and a nice small size. Got it mounted up and used a 22x10 prop. The engine can turn it to 4500rpm. True hp at this rpm is 1.5. Sure it can develop more hp at a higher rpm but then much smaller prop. The UMS glow style carb has the classic way over rich condition at mid throttle. The trick of adjusting the throttle mixture at half opening still was unsatisfactory. I made an adapter on the lath for the Saito 90r3 carb and that was the ticket! Beautiful ideal mixture at all throttle settings with immediate response. All cylinders at same temp. A 4oz tank runs the engine for 15 minutes with some part throttle settings. The question now is will the seals in the Saito carb hold up on gas? Reliable idle at 1000rpm

-Tom

For sure, Tom, I thought that engine looked familiar!! Would really like to see a picture of your Fly Baby at the field, fully dressed and ready to go!!

engines with cdi systems and which are difficult to run well in all situations.
There you can advantageously drive with iridium spark plugs.
stronger spark and better combustion.
goes well with a slightly richer setting.
I have it on some methanol engines.
Lars

Better pictures!
 

https://cimg2.ibsrv.net/gimg/www.rcu...dd24ae2cd0.jpg
https://cimg4.ibsrv.net/gimg/www.rcu...58d9ad2bb9.jpg
https://cimg3.ibsrv.net/gimg/www.rcu...234c8b8be2.jpg

Very, Very nice Tom and thanks for posting the pictures. I would really like to see this plane in the air sometime. I'll let you know the next time we head your way.

Gary

Alert! Loose bolts...
 

I was running my 5-100 and it was developing more vibration. I shut it down and spotted a hex bolt on the floor. It was from the front timing chest. The other bolts were quite loose! I cleaned everything off and reinstalled the fallen bolt and tightened all of them up. Vibration gone. I checked my new 7-35 and the front bolts were loose there too! Check your bolts folks!!! -Tom

It is a shame that this thread has faded. The most important information will be how well these UMS engines last after several flights. I hope information will begin to trickle in. -Tom

UMS 55cc
 

Thanks for the info Tom on the carb. Since you're concerned about the seals on the Saito carb, I wonder if it would be better to adapt the UMS 75cc carb instead.

GI, the one UMS engine I had problems with was the 75. I bought one and Adrian sent me two Walbro carbs with it. One was overly rich at idle and full throttle because you had to with an ultra lean midrange throttle position. The other carb was the opposite with an overly rich mid throttle position. The engine also built up massive carbon on the heads preventing valve closure. The 55 with the Saito carb and the stock 5-100 are basically perfect runners. Adrian took care of me with the 75. He believes in customer satisfaction. -Tom

Well, maybe there just aren't that many guys putting radials on to their planes and that's why things have quieted down here. I flew my "17" four time this past week which brings the total flight count up to 30 with the UMS260cc up front. I cannot say enough good things about this engine. Needless to say it is nothing remotely similar to it's predecessor.

I was at the AMA headquarters last year for the warbird meet. 20 radials I counted! Probably a lot more in Florida and out west. Very glad to hear your 260 is serving you well. Adds confidence. I do have a Moki 215 on a Super Flyin' King with 300 flights over 7 years. Shows no wear.......I do add gear oil to the timing chest. -Tom

Tom,
Would you consider machining another adapter for my 55cc and I will buy the Saito carburetor?
I will be working on my Gilmore Red Lion this year to put the UMS 55cc in.

Tom,
What brand/weight of oil/grease do you use in the gear case?

EDIT: I should have said "Cam Gear Case".

Gary