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HelicopterEngines Plugs Mufflers Fuel › Ys 50st problem in my SDX
12-01-2011 03:59 PM  5 years agoPost 1
jdk737

rrNovice

Peoria,Illinois

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I have been running a YS50st in my SDX for 2 years. It has never given me any issues. The engine was perfect. Now out of the blue it won't start. I have taken the carb apart and cleaned it and put it back together very carefully.

Pressure is building in tank, I get the psst when I pull the plug after cranking.

Needles are correct

Plug is good.

Bought a new gallon of 30% cool power, fuel was my 1st suspect.

When I crank I see and smell smoke.

Simply will not turn over.

I have googled this issue and can't see to find anything that will help

Thanks for any ideas, Im about ready to buy new motor.

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12-01-2011 05:54 PM  5 years agoPost 2
Four Stroker

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Atlanta

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Take the regulator apart and see if you have a hole in the diaphragm OR if it is clogged up.

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12-01-2011 07:17 PM  5 years agoPost 3
jdk737

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Peoria,Illinois

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Ok I'll do that again and take a close look. The diaphragm is cupped and I reinstalled it with the cup facing out, does that sound right?

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12-01-2011 07:48 PM  5 years agoPost 4
Four Stroker

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Atlanta

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Yeah. Lip on diaphragm facing out/up. Point on black disk facing out/up. Make sure the metal valve and spring #YS5332 Reg. Body A is still working by pressing in on it while blowing in the fuel line (while removed from reg.). Make sure all of the holes and passages in the carb. insulator and reg. body are not clogged up. O-rings sealing ? Nipple tight ? A can of compressed air is useful for trouble shooting.

Did you run it lean and seize up the ring ?

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12-01-2011 08:19 PM  5 years agoPost 5
jdk737

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Peoria,Illinois

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I took it all apart and all looks to be in order. The diaghram looks good, however very cheap to replace if you think it's possible to be damaged and not be obvious. The regulator and diaghram was wet with fuel so it is drawing fuel.

I always ran engine on the rich side and periodically checked temp. So I can't imagine that I seized up the ring. How would I know? I can turn the engine over by hand and it feels normal to me.

Thank you Four Stroker for all your help.

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12-01-2011 09:24 PM  5 years agoPost 6
Josh Kussman

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Superior, NE

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sounds like the motor needs rebuilt, need to check the ring, piston and cylnder wall to see if its damaged, if you see vertical scoring its time for a rebuild. if you got two years out of it you did pretty good. good luck

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12-01-2011 11:04 PM  5 years agoPost 7
rexxigpilot

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Florida

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How do you know the plug is good? I would change it before tearing apart the entire engine.

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12-01-2011 11:53 PM  5 years agoPost 8
Josh Kussman

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Superior, NE

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i had the same problem with OS 91, it still puts little bit of pressure into the tank there just is not enough pressure to push the piston enough to get it to fire with out flooding it unless you have a starter that will turn it over faster. if you don't want to take it apart pull the head off and look at the cylnder, its less work and time to just pull the motor is not that hard to take it apart just remember how it all goes back together. if your getting alot of fuel out of the pipe while trying to start and the motor does not lock up from it thats a pretty good sign also, a good motor will flood and it gets hard to turn over, a 90 anyways.

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HelicopterEngines Plugs Mufflers Fuel › Ys 50st problem in my SDX
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