RunRyder - What The Heck Would Cause This???? (Hyper 50)

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Engines Plugs Mufflers Fuel > What The Heck Would Cause This???? (Hyper 50)

TMoore
rrProfessor
Location: Cookeville, TN

Quote

scored piston and ring failure OS 50 Hyper

Today is the 3°piston and ring broken on the exhaust port side when the engine was at middle range(medium rpm). Two of them in my first engine, the last one in my new os 50 hyper with 10 gallons.
I am using fuel 10% nitro, 18% oil blend plus castor oil (adding castor oil by myself, total oil content 20%)I usualy like to use a rich setting (high needle 1 1/2 turn), you can put your finger on the back plate for ever.
The mixture control screw was 20° to the right lean side
I don´t know was this happen again, I am using the same helicopter, the same pipe MP2, but a new engine and extra castor oil.
I asked to engine support and they said me: It could be that your rings are just wearing to the point of failure. If you are consistently wearing through rings after 10 gallons, you may want to start inspecting them for excessive wear when you get to 8 or 9 gallons and replace if necessary.
I think they are right, because in my first engine I broke the second piston after 10 gallons too.
What do you think about this, same ideas??

Unless you are flying in a sandstorm, that looks like a lean run to me.

TM

"If you can do it, it ain’t bragging." - Will Rogers

01-18-2008 10:41 PM

Suki
Heliman
Location: Buenos Aires, Argentina

Thanks a lot for the information, here are the pics of my 3 piston.
PD: I am using a header tank

01-18-2008 10:52 PM

helibatics
Heliman
Location: Cheshire, UK

I tend to agree with the worn ring theory.

I had my ring wear down and found this out when I re-assembled my engine after replacing the rear bearing. When I reassembled the piston and liner, I turned the engine over to check nothing was wrong and heard a light 'click' The engine was locked solid.

The end of the ring had moved and got caught in the front inlet port and locked the engine.

When the ring wears enough, the gap becomes big enough that the locating pin is no longer thick enough to stop the ring from rotating to the point that the end of the ring slips into the inlet port.

If this were to happen while the engine is running, the damage you show on your failure would most certainly result.

Only a small amount of dust will cause a lot of wear on the ring.

I replaced my ring and it's been fine ever since. BUT I will check the gap more regularly to avoid failure.

01-19-2008 12:28 AM

airdodger
Key Veteran
Location: Johnston USA

The burned oil inside the piston is a good indicator the piston is getting too hot. The parts should look like new after that short a time.

Chris

01-19-2008 12:47 AM

SkateFreak
Key Veteran
Location: Cambs UK/Luton

Hey,
I just had a piston do Exactly that... accept it wasnt burnt heh.
2 years service on it... proberbly just got old...
Will stock up on piston rings from the US though

-Jvr

01-19-2008 10:35 PM

Suki
Heliman
Location: Buenos Aires, Argentina

Last weekend I have broken the 4 piston and ring on the
exhaust port side when the engine was at idle range in an auto-rotation training section. (the piston failure is in the same part like the others 3)
Only 4 Gallon trough it. The ring was OK, without wearing down signs
I don´t know was this happen again, I am using the same helicopter, the same pipe MP2.
This happened 4 times in two differents engines, different fuel(in the first 3 synthetic/castor oil, in the last one 100% synthetic oil), the only common things are MP2 pipe and I AM USING EVERY WEEK END TRI FLOW LUBRICANT WITH TEFLON LIKE AFTER RUN. In my club other people use the same fuel, few have the MP2, but I am the only one that at the end of the day empty the engine and put tri flow.
Could the tri flow be the problem?

Today I was rebuilding it, I put a new piston, ring and cond rod, the liner was Ok and I use the same (after roughen the surfase with sand paper). I saw small movement inside the connecting rod (between conrod and crank pin, the crank pin has a little wear) and same small blows on the bottom part of the previous connecting rod (between con rod an cranckcase)the engine is 1,5 year old.
I saw others engines with the same clearance between con rod and crank pin without this problem.
Any Ideas?

07-10-2008 02:54 AM

rcadd1ct
Elite Veteran
Location: Richardson, Texas

Looks lean to me.

The scores on the side are most likely at the exhaust port.

It is getting too hot and you are cooking off all the lubrication.

-RCA .......... Making Cuisinarts Fly!!!!!!!

07-10-2008 03:24 AM

PJRono
Senior Heliman
Location: Ham Lake, MN - USA

You are running lean. Wearing the ring out will look like that too, but the motor should run fine for at least a flying season with very heavy use. Mine typically last 3 years. YS motors look the same when you wear out a ring.

The Crappie Flop is my favorite dance!

07-10-2008 06:34 PM

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Engines Plugs Mufflers Fuel > What The Heck Would Cause This???? (Hyper 50)

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