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07-11-2014, 09:44 PM | #1 (permalink) |
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Join Date: Oct 2008
Location: Midland, Michigan
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YS 91sr flooding
Hi guys,
I have a YS 91sr in my 700N which seems to flood really easily. Pulling the plug, there's a ton of fuel which blows out when I crank it. It then starts and runs great so far. About 1.5 gallons through it, breaking it in so far. Running very cool, and rich for now. I know all about bleeding off the pressure in the tank and such. I typically fuel it up and keep the tank full in storage and between flights. I vent off the pressure, pinch the supply to the carb and fill it. Between flights during an outing, it's been pretty bad about this. I don't open the carb line pinch until I am ready to fire it up. Is there a method that prevents flooding, or might there be an issue which I need to diagnose which causes this, but then seems to run fine. If there's a problem with the regulator, wouldn't it cause problems in running quality? Thoughts?
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07-12-2014, 06:17 AM | #2 (permalink) |
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Join Date: Jun 2010
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Hey Rob, might your idle screw be set to rich? Have you tried the pinch test on the fuel line to see how long it takes for the engine to shut down after pinching the fuel line?
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07-12-2014, 07:09 AM | #3 (permalink) |
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Join Date: Feb 2009
Location: Montreal
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Also, running very cool, very rich for a long break-in period is of little value.
One or two tank of that it quite enough. You have to bring the engine to be warm/hot for the break-in period to work. Quick and dirty method (after those 1 or 2 first tanks) is to simply remove collective and cyclic pitch (from your radio settings) and run through your regular flight with some pauses - first gallon maybe 2minutes of flights and then 30sec pause, 2nd gallon 3 minutes and 3rd no stop and then 4th you can put back your collective and cyclic. This is 'my' recipe/experience, others may have others ! |
07-12-2014, 11:19 AM | #4 (permalink) |
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Thread Starter
Join Date: Oct 2008
Location: Midland, Michigan
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Thanks to you both for your suggestions. Much appreciated input. I did set up with less pitch, plus, I've simply gone easy on the pitch when flying. It's ready to lean the mix a little and eek some power from it.
Is it better to get the mix set before adding pitch back? I was thinking similarly about too cool of a break-in period. But certainly, by now, it should be as broken in as it will get. It had about 3 tanks through, when I bought it, and internally, it looked new. Brown color to the ring. I've not tried the pinch test now that you mention it. Good suggestion.
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07-12-2014, 12:19 PM | #5 (permalink) | |
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Join Date: Feb 2009
Location: Montreal
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Quote:
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07-12-2014, 01:40 PM | #6 (permalink) |
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Thread Starter
Join Date: Oct 2008
Location: Midland, Michigan
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Thanks again for the input
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07-12-2014, 05:14 PM | #7 (permalink) |
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Join Date: Jan 2013
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The YS120 is prone to flooding too. Had to remove glow plug and push fuel out after almost every break in flight. Once broken in and tuned it is much better.
As soon as you shut off the engine after a flight, pinch the fuel line. For your next flight, let the line pinched, start the engine and then open the line. Getting the idle and mid needles right is critical for a good tuning. Running a hotter glow plug for break in can help as well. |
07-15-2014, 09:49 PM | #8 (permalink) |
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Thread Starter
Join Date: Oct 2008
Location: Midland, Michigan
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I spent some time Sunday setting idle. It was very interesting. I have a fuel shutoff in the carb line for this purpose. So, I removed blades, set my pit table (makes it easy to repeatedly fire the engine without stooping down). I tuned the idle to get it smooth running. I found it was a hair rich, but if I tuned it lean enough to get a 4-5 second time to stop, it was pinging and knocking pretty hard. So, I simply tuned it to be a nice, smooth idle. It takes more like 7-8 seconds to die. I then found I could reduce the idle a good bit which reduced the clutch grabbing. I then repeatedly stopped/started the engine with using the throttle kill, and also using the carb line shutoff and was able to eliminate all flooding. I think this engine is getting pretty happy.
Next weekend, I will run it at 2000 hs (8.0:1 gears) and begin to fly it more agressively. Maybe push the pitch to 13 if the temps are in check. I am almost exactly to the leaner end of the factory settings. I take it to be the richer settings are a guidline for break-in and the leader end is where to expect it might be at normal tune.
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07-16-2014, 05:54 AM | #9 (permalink) |
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Join Date: Jan 2013
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YS 91sr flooding
Pinch test is not a good reference when you have an engine with a reg. Your ear is best. Breaking in the 120 the mid was flooding the engine so you'll need ti tune it and the high too to reduce flooding. Keep the line pinched after each flight.
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