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YS FZ 110s won't stop running

Old 12-20-2007, 03:47 PM
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42etus
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Default YS FZ 110s won't stop running

I've got a new FZ110s that won't stop running when the throttle is closed. The engine is mounted in a plane and the idle is very reliable, set at 2000 rpm. When i hit my kill switch, the throttle closes all the way, but the engine doesn't stop. It drops down to about 1600 rpm and just ticks merrily along. What's up with that? Like I said, the engine is new, with only 3 tanks of fuel through it. The throttle valve has a small V shaped notch in it which I think is allowing just enough air in to keep the engine running. Why is the V notch there? Other than that, this engine runs great.
Paul
Old 12-20-2007, 06:30 PM
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Troy Newman
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Default RE: YS FZ 110s won't stop running

Yes the V notch is there to improve the idle. Its job is to let a little air past while at idle rpms. To kill the engine you will have to get the barrel to close past the little "V"

You need to close the throttle barrel further. If the "V" is allowing too much air to pass it will continue to run. There is a throttle barrel stop screw. If your servo is driving the throttle arm to its stop on your "Kill" setting then you need to adjust the throttle barrel stop screw just a little until the barrel will close far enough to actually shut the air off.

Usually they come set at the factory with the this stop screw at the right position to get a kill on the barrel, but sometimes you have to adjust it. This is the screw with the spring on it right next to the carb opening. Turn it CCW to get more travel and clockwise to get less rotation closed.

Be careful not to loosen the screw too much. A small spring keeps tension on the screw to keep it from falling out with vibration. You want to loosen the screw just enough to let the engine quit and no more.

Another option or solution to try is to richen the low end air bleed screw just a little. If you richen it just a little maybe 1/8th turn the engine will quit when you pull the kill but it will not be too rich and load up at idle. You may have to play with it a little bit....but I would try a little richer on the low speed air bleed screw. You turn this screw IN or CW to richen the mixture.

It may be a combination of allowing the barrel to close just bit more and it also may be the mixture is a little lean on the low end...

Please let me know if you have trouble. It should be a piece of cake. They usually don't idle that low when their are new. However they are all a little different and some take a bit longer to break in than others.

Troy Newman
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Old 12-22-2007, 08:00 PM
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42etus
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Default RE: YS FZ 110s won't stop running

Thanks, Troy. I backed the stop screw out a little, now the kill switch works fine. Sometimes the most obvious things are the hardest to see! I tell you, I just love this engine. The idle is perfect right out of the box. Mid range was a bit rich. I turned the regulator in 1/8 turn, now it's fine. Thanks again and Merry Christmas.
Paul
Old 12-22-2007, 08:04 PM
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Troy Newman
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Default RE: YS FZ 110s won't stop running

Ok so you LEANED the bottom end and it solved it?

I would have though richening it would solve it. The low speed needle on that engine is an air bleed screw and works backward froma needle valve.

I'm glad you got it working now....I just want to make sure you understand the way the low end works on the engine...many folks get confused at this. IN (CW) is Rich and Out (CCW) is Lean. You also leaned the regulator by dialing it IN...

Chances are the regulator had the larger affect. The air bleed screw is a fine tuning adjustment at that 2000rpm only it doesn't work much higher, and the regulator will affect the low end too.....


But now you are good and that is what is important.

Merry Christmas

Troy
Old 12-22-2007, 11:46 PM
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Default RE: YS FZ 110s won't stop running


[quote]ORIGINAL: Troy Newman

Ok so you LEANED the bottom end and it solved it?

I would have though richening it would solve it. The low speed needle on that engine is an air bleed screw and works backward froma needle valve.

Troy

Well, no. What I did to solve the "won't stop running " problem was to back the idle stop screw out about 1 turn. That allowed the throttle valve to close enough to kill the engine. I have not needed to touch the idle air bleed screw. It seems to be perfect right out of the box. Heck, the thing will idle at 1600 rpm for 10 minutes then transition to full rpm without missing a beat.
Then what I did do was to lean the regulator about 1/8 turn in because the engine would load up in the midrange. The 1//8 turn was about right, since it nolonger loads up.
Anyway, thanks for the help.
Paul
Old 12-23-2007, 12:52 AM
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Troy Newman
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Default RE: YS FZ 110s won't stop running

OK...

I was a little confused...thing you were back out the mixture screw....and not the barrel stop screw.

You are right.....

By the way the richer regulator setting and the extra air from the "V" is what was keeping it running down there at those low RPM...

Glad you are set.

Merry Christmas

Troy Newman
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