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HelicopterEngines Plugs Mufflers Fuel › os 50 hyper low comp & wont fire help
01-03-2010 01:40 AM  7 years agoPost 1
danthemancarol

rrNovice

charlotte,nc

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Like it says. Took head off, looks fine. Checked Carb tasked.fine put new gasket on cymp3. Checked plugs,they're fine. Need some troubleshooting help fellas

Dooh, damn dumb thumbs......

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01-03-2010 01:42 AM  7 years agoPost 2
george0079

rrElite Veteran

USA

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has it been run lean? did it get too hot?

Pull the piston/rod assembly and check the ring and cylinder for damage

Hell... I can fix that.
Uh oh..
Nope.
It's ***ked!!!
RE-KIT!!!!!

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01-03-2010 02:09 AM  7 years agoPost 3
danthemancarol

rrNovice

charlotte,nc

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what would i be looking for?? it did run hot a couple of times ;(

Dooh, damn dumb thumbs......

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01-03-2010 02:12 AM  7 years agoPost 4
george0079

rrElite Veteran

USA

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you're looking for scoring marks where the ring and liner tried to seize together.

Hell... I can fix that.
Uh oh..
Nope.
It's ***ked!!!
RE-KIT!!!!!

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01-03-2010 03:40 AM  7 years agoPost 5
dkshema

rrMaster

Cedar Rapids, IA

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If you're really low on compression you have a problem somewhere in the piston/ring/cylinder, since you've already checked the head for tightness, as well as the plug.

If you had the head off and didn't see a hole in the top of the piston, your choices narrow down to the ring and perhaps the cylinder liner.

The ring could be just plain worn out (lots and lots and lots of fuel).
The ring could be stuck in the ring groove.
The ring could be broken.
The engine could have been run too lean, messing up the piston, ring, AND cylinder liner.

If it's been run too lean and damaged, the damage is most likely to be found on the piston skirt and ring in the area of the exhaust port, as this is where the highest temperatures will be found in a lean run. The piston skirt will have visible scarring/galling in the exhaust port area and the ring may be stuck in the groove from all the aluminum being smeared all over the place.

-----
Dave

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

Team Heliproz

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01-03-2010 05:33 AM  7 years agoPost 6
danthemancarol

rrNovice

charlotte,nc

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I have had this apart before to change bearings. the piston head looks fine not even colored that bad. The ring you refer to, is that the ring that goes around the top of the piston? Guess I will have to dissasemble her whaaaa

Dooh, damn dumb thumbs......

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01-03-2010 05:35 AM  7 years agoPost 7
dkshema

rrMaster

Cedar Rapids, IA

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Piston ring...yes, the only ring that goes around the piston. It is what actually gives your motor compression in the first place.

-----
Dave

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

Team Heliproz

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