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HomeRC & PowerAircraftHelicopterEngines Plugs Mufflers Fuel › Rovarossi 91 running lean
08-27-2013 07:55 PM  5 years agoPost 1
Slowpoke

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Dublin, OH

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I have a Novarossi 91 in a TRex 700 that is running very lean. It was running fine at the end of the season last year, and has been sitting on a shelf until a week ago when I started flying again. The motor got very hot very quick, after only a minute of hovering. The motor has less than 20 flights on it.

I pulled the motor and checked the head and backplate, both tight.

1 replaced all the fuel lines, inside and outside the tank.

Took the carb off and flushed it with carb cleaner. Made sure the o-ring was ok.

The Rovarossi Rex H9 pipe attaches to a manifold, that seals with just 2 O-rings. Put in new O-rings, but this doesn't seem to me like that is adequate to get a good seal. Any way to check if this is the problem area?

I'm not running header tank. Although it ran fine last year without one, should I start using one? I don't do 3d, just sport flying.

I'm running Cool Power 30%

Needles are at factory specs - 1 turn out idle, 2 turns out mid, and 3 turns out high.

Doug Roberts
Dublin, OH

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09-19-2013 06:09 AM  5 years agoPost 2
TMoore

rrMaster

Cookeville, TN

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Richen it up and let's see if it will go rich and hold.

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09-19-2013 03:38 PM  5 years agoPost 3
jbjones

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Columbus, Mississippi

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Doug,

Have you changed fuel, or anything like that since it last ran well?

I've got a V1 in one of my Tempests. Honestly, I've had fits with it. Mostly from overcompression. It gets very hot, very quickly. No amount of richening helps. It's either so rich it can't lift off, or slowly leaning/overheating itself.

I've added another shim, but haven't flown it yet. If you've changed anything, you may want to consider looking at the compression.

As far as the exhaust seal, yes any leak there would cause some erratic behavior. However, I can't really think of a good way to test the seal on that header/pipe combo (I have the H9 as well). I've never really given much thought to the seal on it.

-JB

J. B. Jones

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09-19-2013 04:48 PM  5 years agoPost 4
Slowpoke

rrKey Veteran

Dublin, OH

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If I set it any richer, it doesn't have enough power to keep a stable hover.

Nothing has changed that I'm aware of, as it's fairly new.

Just as a test to see if there was an air leak, I completely sealed the pipe/manifold joint, manifold/engine and carb joint with high temp silicone, and it still gets hot quick. I'm thinking internal engine damage like a bearing or scored cylinder.

I decided to cut my losses and bought a new Align 91 motor. Put it in 2 days ago. It fired right up, and is running nice and cool.

I've got 6 tanks thru it so far, and have been gradually leaning it out. It's making good power, and I can hold my finger to the backplate as long as I want.

Thanks for the replies.

Doug Roberts
Ohio

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09-20-2013 02:07 AM  5 years agoPost 5
scootr

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Australia

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Could be a crook rear bearing from sitting on the shelf.

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09-20-2013 02:59 AM  5 years agoPost 6
TMoore

rrMaster

Cookeville, TN

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NovaRossis are good for wide open running. They aren't good for much else.

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