I can see one improvement... they went to a standard sized prop shaft. I had to cut a 13mm center hole in the props for the older motor... makes the prop useless for anything else.

Originally Posted by Kiva Flyer

Is that Van Morrison in the background? And why does it run cooler with 100 octane? How often you gotta lube those open rockers? I do like me some radials, though.

Rule of thumb,the higher the octane rating,the cooler the burn because it takes longer to burn.

Originally Posted by reyn3545

I can see one improvement... they went to a standard sized prop shaft. I had to cut a 13mm center hole in the props for the older motor... makes the prop useless for anything else.

Hi Mike. Good to see you posting.

Originally Posted by Kiva Flyer

Is that Van Morrison in the background? And why does it run cooler with 100 octane? How often you gotta lube those open rockers? I do like me some radials, though.

It is recommended the rockers be lubricated once at the beginning of your flying session.

I personally like to run high octane non ethanol 91-93 in my RC gas engines. The main reason would be to prevent early predetonation during compression due to a hot spot in any carbon deposit that may be present on the cylinder head. The higher octane % will ignite at a higher compression level allowing the cylinder to be closer to its maximum stroke height before ignition hense, making better use of its power. Our model engines don't have sensors to retard timing when lower grade fuels are detected causing engine knock like in our automobile engines. I plan to use 91-93 fuel for break in on my UMS 7cylinder 160cc radial. I will then try some 100LL aviation fuel and record cylinder temperatures to see if they actually do run cooler with the higher octane mix. I would be glad to share my findings with anyone interested. ��

Originally Posted by reyn3545

I had one of the UMX 260cc motors from Horizon... constant problems with oil leaks, and the motor never ran consistently... great one day, very sluggish the next. I never got the motor off the ground, sold it and put a Moki on my plane... problem solved. I hope UMX worked out their problems, from what I read, there were a lot of people with the same problem as me.

I noticed the same issue on one of the scale events, 1 day great, next 2 days very bad performance. The person was using an APS fuel pump as well.

On all radials is better if you use a fuel pump.
In terms of one day runs good one day bad, one good , one bad sort of say...is not a roller coaster, if engine goes bad will be bad. The internals are the same today, tomorrow and the day after. Metal does not have a mind of it's own. Could be couple things , temperature / humidity,carb setings, the pump may not supply enough or to much fuel. The spark plugs may get oil in them during storage . point is metal is metal it either shines or breaks...LOL

got to say i like the way they look and was impressed with the running of the motor on the video

Originally Posted by CH Ignitions

On all radials is better if you use a fuel pump.
In terms of one day runs good one day bad, one good , one bad sort of say...is not a roller coaster, if engine goes bad will be bad. The internals are the same today, tomorrow and the day after. Metal does not have a mind of it's own. Could be couple things , temperature / humidity,carb setings, the pump may not supply enough or to much fuel. The spark plugs may get oil in them during storage . point is metal is metal it either shines or breaks...LOL

hahaha very true!!!! just like any other motor

This new radial option makes me think I should finish my GeeBee's.

Originally Posted by DESERTRIDER49

This new radial option makes me think I should finish my GeeBee's.

Check this out! This is a carf GeeBee R2 with an evolution 7-160 engine. I have the new UMS 7-160 on my test stand right now and when I came across this old video it made me stop and think.....GeeBee or Stearman? Lol.

Gee Bee R2 Delmar Benjamin CARF radial engine RC (5 min 57 sec)

Today I ran my new UMS radial 7-160 I received from Adrian at CH Ignitions. I put three tanks of fuel through it so far and am impressed. I did a little fine carb tuning and got these results. Prop: Sail - wood 28x12 2blade, Fuel: 91 non ethanol, Oil: Quick Silver Full Synthetic 2cycle mixed 20:1(6.4oz) per gal. ,Idle: 1000, Full throttle 5400. Same results with RC excel fuel pump connected or without. Cylinder temps 164 deg F. Transition was crisp and darn near blew my hat off even though I was slightly out of the main prop wash �� Was able to hand start this beast once I got a couple tanks through it and had the needles adjusted better. It sounded like it would idle all afternoon, and whenever I punched the throttle it roared to life. Midrange was smooth and clean too. Love it!

Today I ran my new UMS radial 7-160 I received from Adrian at CH Ignitions. I put three tanks of fuel through it so far and am impressed. I did a little fine carb tuning and got these results. Prop: Sail - wood 28x12 2blade, Fuel: 91 non ethanol, Oil: Quick Silver Full Synthetic 2cycle mixed 20:1(6.4oz) per gal. ,Idle: 1000, Full throttle 5400. Same results with RC excel fuel pump connected or without. Cylinder temps 164 deg F. Transition was crisp and darn near blew my hat off even though I was slightly out of the main prop wash 😀 Was able to hand start this beast once I got a couple tanks through it and had the needles adjusted better. It sounded like it would idle all afternoon, and whenever I punched the throttle it roared to life. Midrange was smooth and clean too. Love it!

Originally Posted by clockguypete

.....GeeBee or Stearman? Lol.
https://youtu.be/VJutXFFAnRE

If you are asking my opinion, the GeeBee is a race plane and must be flown as such, while the Stearman can loaf around the sky and do slow big maneuvers. so, one of each would be just right.

Originally Posted by DESERTRIDER49

If you are asking my opinion, the GeeBee is a race plane and must be flown as such, while the Stearman can loaf around the sky and do slow big maneuvers. so, one of each would be just right.

Haha I like the way you think, one of each...... perfect.