YS 140L idle problem

[Earl Haury]

Ihncheol

Suggest changing the "plunger" valve - the silicone valve that the regulator 
spring sets on - these will deteriorate over time (with or without engine 
runs) and allow fuel to leak through the regulator. One way to check is, 
with the system pressured up - engine not running, is this. Remove the fuel 
line from the carb, there should only be a spurts of fuel exit this line as 
the engine is rotated. Fuel flowing continuously signifies a leaking 
regulator. (Another clue regarding a leak is that the regulator is 1/2T 
open - normal is flush with the housing.)

As to the upright / inverted thing. When the engine is upright any excess 
fuel is swept from the crankcase by the airflow continuously. However, when 
inverted at idle some of the excess fuel will accumulate in the piston 
cavity, eventually a large quantity will get to the airflow and flood the 
engine (plug).

Earl


----- Original Message ----- 
From: "Ihncheol Park" <PatternFlyer at sbcglobal.net>
To: "NSRCA" <discussion at nsrca.org>
Sent: Saturday, January 08, 2005 2:26 AM
Subject: YS 140L idle problem


> Hi, All,
>
> I got a friend in Gainsville, Florida who is having trouble running a YS
> 140L.  The engine has about 2 gallons through it.
>
> It is mounted in a 2m pattern plane.  OS-F, Coolpower 20%.
> The engine runs well above idle. (If the plane is inverted; the upright
> position for the enigne, the engine idles well for a long period).
> 1.5 turns for the highspeed needle and the idle also similar.  Regulator 
> is
> slightly open (maybe around 1/2 turn)
>
> He says the engine spits a lot of fuel in upright or inverted position
> during running and/or stopped.  Check valve is fine, diaphram is fine,
> adjusting the idle airbleed screw didn't change much.
> He already checked for any debris around plunger and regulator housing.
> Still the same.
> He's got two of 140L, but only one is doing this.
>
> I am not sure how he sets the idle, but was told that the high is around
> 8700 rpm.  No idea about prop, but I believe APC 15.5x12 which I gave him.
> I am not sure if his engines have the piston modification.
>
> Any idea?
>
> Thanks,
>
> Ihncheol Park
>
>
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