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HelicopterEngines Plugs Mufflers Fuel › OS 55 Carbon or burned piston?
12-13-2016 01:38 PM  11 months agoPost 21
ICUR1-2

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Ottawa, Ontario

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engine porn

just make sure that ring locates the seating pin

spending time, paying attention

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12-13-2016 01:56 PM  11 months agoPost 22
wjvail

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Meridian,​Mississippi

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engine porn
Funny.

More engine mysteries....

I happen to have a picture of the piston in my 55 only because some number of years ago something passed through my engine and pitted the head and piston crown. It did absolutely no other damage. The plug was not only broken but showed signs of mechanical damage. I decided more investigation was required and this is what I found.

My first reaction was to replace the piston and head but in the end said screw it and put it back together. That was many gallons ago and the engine is going strong.

I never did figure out what caused this. The engine is still installed in my Raptor .50 Titan.

"Well, Nothing bad can happen now."

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12-13-2016 01:59 PM  11 months agoPost 23
don s

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Chesapeake, VA

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Sand ingestion maybe?

E820, Raptor G4N, X50F/E, E620, Forza 450, and some planks.

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12-13-2016 02:29 PM  11 months agoPost 24
ICUR1-2

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Ottawa, Ontario

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fuel detonation was off

timing was off would cause pitting, wrong shim or fuel nitro content or glow plug

spending time, paying attention

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12-13-2016 03:34 PM  11 months agoPost 25
don s

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Chesapeake, VA

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Maybe something in the plug got loose and went through the engine?

E820, Raptor G4N, X50F/E, E620, Forza 450, and some planks.

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12-13-2016 04:05 PM  11 months agoPost 26
dasd

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Carol Stream, IL

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Original Post

The ring was stuck and I broke it trying to remove it. So, it's gone in that first pic.
I happen to have a picture of the piston in my 55 only because some number of years ago something passed through my engine and pitted the head and piston crown.
The last time I was something like that, it was a rear bearing self-destructing.

Formerly SunFunFlyer.

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12-13-2016 05:40 PM  11 months agoPost 27
GHT

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Cleveland, OH

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Was a fuel filter installed? If so, was the filter material intact?

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12-13-2016 05:53 PM  11 months agoPost 28
MOZENZ

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Denby Dale UK

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It is interesting I have had a look a pictures of OS piston. The OS50 Hyper look plain below the ring and no relief by wrist pin. The OS55 has a fine groove below the Piston ring. The OS 50 engine I have on the bench like at

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12-13-2016 06:00 PM  11 months agoPost 29
dasd

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Carol Stream, IL

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GHT: no fuel filter in the tank.

Formerly SunFunFlyer.

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12-13-2016 06:24 PM  11 months agoPost 30
GHT

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Cleveland, OH

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Was a fuel filter installed between the outlet of the fuel tank and carburetor inlet?

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12-13-2016 06:45 PM  11 months agoPost 31
dasd

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Carol Stream, IL

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Yes. I use one with the fine metal screen. I back flushed it and it was clean.

Formerly SunFunFlyer.

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12-14-2016 12:55 PM  11 months agoPost 32
dkshema

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Cedar Rapids, IA

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I wonder when OS changed the piston style.

But back to the problem. It looks like ypur ring got stuck in its groove and failed to seal properly. Maybe you got away with a lean run in the past, doing inly slight damage, or maybe a small bit of FOD got in the cylinder.

Was the cylinder scored in that area?

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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12-14-2016 03:54 PM  11 months agoPost 33
wjvail

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Meridian,​Mississippi

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I wonder when OS changed the piston style.
Good question. I've noticed that sometimes OS will make a small visible change to distinguish a product that has been changed in other less obvious ways. For instance, OS could have at some point lightened the piston or changed material and distinguished the two by cutting a small oil grove in one variant. The two small grooves in this piece, where the throttle arm attaches, suggest there was earlier versions.

My best guess is that the 55 always had an oil grove and the 50 never did. Do you have a 55 with an oil grove?

Bill

"Well, Nothing bad can happen now."

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12-14-2016 03:58 PM  11 months agoPost 34
wjvail

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Meridian,​Mississippi

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Anyway. The OPs engine looks like it ate something - like a mud dauber. Something is stuck all over the piston and synthetic oil won't do that. Maybe there was some gob-a-goo in the fuel. Sugar, lacquer or something else dissolved in the fuel. Contamination from gummy castor or otherwise inappropriate 2 stroke oil comes to mind.

I remember you said you have another engine that is in perfect working. Have you been running the same fuel in both? Have you had the head off the other recently?

Now I'm just grasping at straws.

Bill

"Well, Nothing bad can happen now."

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12-14-2016 04:29 PM  11 months agoPost 35
dasd

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Carol Stream, IL

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I haven't lost sleep over it. I'm going to rebuild it and move on. It is curious, though. It's kinda like the chicken and the egg. Did the ring stick and cause the problem or did the burn mark gum up the ring?

Formerly SunFunFlyer.

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12-15-2016 01:25 AM  11 months agoPost 36
dkshema

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Cedar Rapids, IA

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My best guess is the ring stuck, the rest is collateral damage.

While you have it apart, remove the rear bearing, and put in a new one. You can always inspect the old one later. Maybe it was on its way out.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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12-15-2016 04:58 PM  11 months agoPost 37
dasd

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Carol Stream, IL

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I agree. I am replacing the bearing. I took it out and it's not in great condition. The new bearings have a 'shield' on one side. It's not a seal. I'm wondering if the shield goes towards the front of the crankcase.

Formerly SunFunFlyer.

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12-15-2016 06:46 PM  11 months agoPost 38
utahbob

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St. George Utah

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Check that fuel closely..

Something got in there..your pic reminds me of the time my "fuel magnet" disintigrated into a zillion specks and got into my 55.

I do a great decending funnel!

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12-16-2016 04:24 AM  11 months agoPost 39
dkshema

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Cedar Rapids, IA

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You don't need a shield on the rear bearing. They remove easily, I'd make sure it was gone before I installed it in my motor. OEM parts don't have them.

You say the rear bearing isn't in good shape. Perhaps bits and pieces are going through the motor, one causing the ring to stick.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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12-16-2016 01:26 PM  11 months agoPost 40
MOZENZ

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Denby Dale UK

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My view on replacement bearings is to ensure they have a plastic cage.
Metal ones are ok but if they fail you wreck the engine.

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