ptdan

Hi hi guys
A question, i have the ums 75-5, it has run about 2 liters. But it suddenly stopped, cant start it again. I found out, it only gets fuel in the lower cylinders. Any ideas??? And im using a Emotec fuel pump.
Dan

n8622t

My Feedback: (8)

It sounds like it’s either the ignition or the pick up sensor. If the bottom cylinders get fuel then so will the top cylinders. Make sure the battery is healthy also, as well as a good functional switch. I’d say you have an electrical problem

ptdan

Thanks Jimmy, i have sent a mail to bigplanes. Thats where i bought the ums, it should be a warrenty problem.. I can not be the carb?????? And there is sparks.

n8622t

My Feedback: (8)

Yes If you have fuel in the cylinders then it has to be spark

ptdan

The sparkplugs are ok, and give a spark when i turn it. When they are out, but it is only one cylinder that gets fuel.. Lets see what bigplanes says

n8622t

My Feedback: (8)

Good idea….warranty is always good

ptdan

Hi again
I found out why it would'nt start or run The y festo for pressure to the carb, was blocked with some plastic.. Maybe from the nylon, but it works.. Happy days....
Dan

DaleD

This is GREAT news. Happy to know your happy days have returned.

Feel free to share a video of your motor in operation. There is no better feeling in the hobby than that derived experiencing a multi-cylinder 4-stroker.

DaleD

n8622t

My Feedback: (8)

Next install is underway…upgrade from Zenoah GT-80 to the UMS 5-180cc on my 1/3 scale BlasaUSA N-28

n8622t

My Feedback: (8)

Previous install of the UMS 5-125cc on a TopRCModels FW190

n8622t

My Feedback: (8)

it’s getting fuel but not enough…good find!! It saves you from shipping it in😃

marksp

My Feedback: (9)

Decided to go with the Black Star 5-250v3 bundled with a model from Tomahawk. The Black Star is essentially a Tomahawk branded UMS radial (virtually identical if not the same as the UMS 5-260). This is my first UMS engine but am very familiar with Moki and Saito radials.

Happy to share engine gets better every flight! Currently collecting & triaging telemetry data from PowerBox CORE - Max RPM during this flight was 4630 turning SEP 32x14 Wilga prop.

Engine starts easy, pulls strong and sounds fantastic!

DaleD

Good day,

Anyone using a FrSky Taranis on OpenTX to fly their multi-cylinder 4stroke engine with the APS PowerFuel pump powered model? I’m hoping to get some help for my UMS 5 75.

I would specifically like to know the programming in the radio used to ensure appropriate fuel flow from idle to full throttle.

Thanks

DaleD

1967brutus

Isn't the carburettor supposed to take care of that, and the pump to be run at constant speed (on/off switch)?
I think you can control the pump from the transmitter, but you could just as well have the pump run when the ignition is on: Priming should not be an issue with an electric pump and that way you cannot flood the engine unless you leave the ignition on without starting it, which one should never do anyway...

DaleD

When I bought the pump it was suggested that I programme for 5% flow at idle and around 40% at full throttle.
I have tried one approach which worked for a while but now there seems to be an issue which I need to troubleshoot and resolve. If it is that I do not need to have the pump operate based on throttle position I would be more than happy to just use an on/off switch.

With an on/off operation, what level of output is suitable? I am figuring that MAX output maybe too high.

Thanks for responding

DaleD

1967brutus

I can't help you there, I was assuming that you would have a fuel pump with a fixed speed anyway, had not heard of "controllable" fuelpumps on gassers before...

n8622t

My Feedback: (8)

My pumps run constant speed with a pressure valve that allows fuel to flow back to the tank, the engine only uses what it needs

DaleD

Did you note a change in the tune of the engine with the pump installed? It appears my engine has gone quite rich.

Thanks

DaleD

DaleD

Thanks for responding.

Wondering about your set up. What pump are you using? With the constant speed operation, are you at maximum output?

Thanks

DaleD

n8622t

My Feedback: (8)

Sure, the pump is on or off running on 4.8v. The pump is from Micropumps and the valve is from USPlastics

GlennM

Hi, have you tried setting up the pump on a spare channel (lets say Ch 6), assign Ch 6 to the throttle and set the pump (throttle) end points at what you think is 5% and 40% (something like -90% for 5% and -20% for 40%) you could also have it assigned to a switch either the ignition kill or a separate switch if you want to turn fuel off whilst engine is running.

Regards Glenn

DaleD

Thanks for the suggestion.

Based on other suggestions from other UMS engine operators, I have decided to operate the pump on an on/off principle using the same switch for the ignition. I had to adjust the sub-trim in the radio to achieve the desired operation.

Regards

DaleD

LtMash1A

I think radial engines have more torque, but how do they compare with traditional single cyl. engines. For example, if the recommended engine is an 80cc for the plane, what UMS radial would be appropriate assuming the cowl will accommodate either one?

LtMash1A

Was there adequate room in the cowl for the 125?

badangle

My Feedback: (1)

Don't forget to factor in the weight difference when doing comparison....also reliability, cost.
yes radials look and sound great, but MY personal experience tells me unless you have veryDeep pockets and lots of patience beware, messing around with radials caused me grief.
evolution 7-77 glow radial and moki 5 cyl 180 gas radial.
bottom cylinders get fouled up and fuel distribution to each cylinder also common issue.
setting valves also complicated.
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Don't get me wrong, if I ever hit the lottery I would get another Moki but