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HomeAircraftHelicopterGasser Model RC HelicoptersEngines › Zenoah 26cc difficult to shutdown...
01-03-2014 06:25 PM  4 years agoPost 1
Rojoalfa

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Punta de Mata, Monagas-Venezuela

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From time to time, when I need to shutdown my spectraG 26cc, it doesn't.
Engine refuse to shutdown.
Carb is closed 100% and Still motor is working ...
So far, I decide to install a kill switch to handle this meanwhile I see what can I do...
Probably, carb is broken or seals not working or seal front bearing is Bad.
Every thing is looking Good, no leaks, I tell You, my zenoah is a clean machine.

Before pulling out the zenoah motor, what tests should I make?

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Saludos cordiales,

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01-03-2014 07:47 PM  4 years agoPost 2
fastflyer20

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N. Tonawanda, NY

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Have you tried pushing the throttle lever closed with your finger? Since it only happens sometimes, you may have some play in the linkage, servo or throttle shaft. Also remove the air filter and make sure the butterfly (brass throttle plate) is not loose.

If linkage, servo and butterfly is OK, then it does sound like an air leak. Since air leaks suck in air, and not usually leak fuel out, they can be hard to find.

Before removing from heli:

With engine idling carefully spray solvent and see if RPM's increase. If RPM's increase, that is where the air leak is.

Areas to check:
Carb gaskets
Throttle shaft
Cylinder to crankcase
Crankcase seals

The most common leak area is at the carb gaskets.
If the gaskets leak, replace them with new Teflon gaskets.
If the throttle shaft has play and leaks, replace the carb
Unfortunately it is not always easy to get near the seal areas to test. If the engine is old or has many flights and will be disassembled, then replace the seals. They are not expensive and fairly easy to replace.

Tom
CAUTION - my posts are based on my experiences, yours may be different.

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01-03-2014 08:05 PM  4 years agoPost 3
RM3

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Killeen, Texas - USA

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if you have no leaks and if your engine still runs after the butterfly is 100% closed, your needles are not set up correctly, especially the low needle...in this case the low needle is way too lean, and you need to open it up a bit.

idealy the way to set them up is so that the butterfly is open by about 1mm for idle position (within TX) and adjust the LS needle to get a good stable idle at that position, then set the HS needle during flight, in which case you may need to play around with the Throttle curve a bit to suit it best. Even if you do use a GOV you still need to set it up right or the GOV will not engage due to throttle endpoints and such or may disengage during flight resulting in over speeding or even bogging death. so your endpoints for the throttle should have the full closed and full open at thier bottom and top endpoints, the throttle curve should have the idle at the 1mm open, and the kill position (if you have that ability in the Tx) should move the carb back to fully closed.

My gassers are set up so that the engines idle with the butterfly open by about 1mm and when I hit the kill switch on the TX the throttle servo moves the carb to fully closed and the engine dies. Ive always felt that a ignition kill switch should only serve as a backup if the servo cannot kill the engine via carb position.

JMTC

showing a preference will only get you into trouble, 90% of everything is crap...

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01-04-2014 01:43 AM  4 years agoPost 4
chickens2252

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Okinawa

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I was a gasser noob 6 months ago. I'm running a stator gator so I have no kill. When I first started at the field I was running so rich for break-in that it would shut down no problem when I closed the throttle but once I started tuning to post break-in it wouldn't. (I plugged the exhaust if anyone was wondering) Only then did I go back and find in the instructions that you have to back out or remove the Idle screw to let the throttle close all the way.

Alternately from automotive work I know that the throttle blade/plate can be mounted incorrectly on the shaft. There is a little play when you loosed the screw in the center of the throttle blade and if the blade isn't perfectly centered when the screw is tightened it can cause an air leak. If you can see light around the blade with the carb removed this could be the issue.

To align it just loosen the screw a little with the throttle closed and retighten. It could take a couple tries.

Tighten it tell it loosens then back it off a quarter

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01-04-2014 01:29 PM  4 years agoPost 5
Rojoalfa

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Punta de Mata, Monagas-Venezuela

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Well, the idea of spray some carb cleaner is very good. I 'm going to try that.

BTW, we removed idle screw to use the throttle cut from radio.
On my first inspection, carburator seem to be all in place.

This is my 14th fl with this motor. I rebuilded using a cylinder from Dave Motor, ported, new piston, ring, bearing, etc...

Still running a little rich.

This weekend is going to be for this tests...

/

Saludos cordiales,

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01-06-2014 01:29 AM  4 years agoPost 6
Toddc72

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weed,ca-usa

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Check for bad iso block. If it is the stock one it is probably warped. You can sand it flat again but it will just do it again. Get the better iso block setup for it. Another thing to look at is make sure you are not over shooting the closing side with the butterfly shaft. Looking at the drawings of it. It has a solid rod going to the carb from the servo. If the endpoint is set wrong it will put a bind in the shaft and bend it. This will allowing it to not close all the way. You are controlling throttle from one end while the stopping side is on the opposite end. This will put a twist in the shaft and if over traveled repeatedly will break the shaft at the screw hole and put the butterfly disc and the screw into the engine. Confirm endpoints are set and not overdone.

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08-27-2014 06:16 PM  3 years agoPost 7
Rojoalfa

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Punta de Mata, Monagas-Venezuela

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Well, i finally did your recomendations...

I found a seal bearing damaged.

Now, my question is... I have two options...

The One from dave motors...dd258

The One form SKF seal bearing 6001 2rsh/c3

What do You recomend?

/

Saludos cordiales,

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08-27-2014 08:26 PM  3 years agoPost 8
fastflyer20

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N. Tonawanda, NY

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Either one should work fine. I have used the ones from DDM.

I would suspect the SKF to be higher quality so it may last longer.

Tom
CAUTION - my posts are based on my experiences, yours may be different.

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08-28-2014 02:41 AM  3 years agoPost 9
geomecc

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Long Island ,NY

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according to al at hanson it's not needed due to there is a bearing there already. but since u have a sealed bearing use either. u have them already.

R I P Roman Jr. Team SKOOKUM SRW EFC

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09-01-2014 01:00 PM  3 years agoPost 10
Rojoalfa

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Punta de Mata, Monagas-Venezuela

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We decided to use... DD258

The One that fails was a SKF... Mmmm...

I am not sure at this time if SKF was a Good choice...

/

Saludos cordiales,

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