YS dies at bottom of stall turn - Help!!

[Dean Pappas]

Hello Eddie,
without hearing your engine, it's terribly hard to tell! On the other hand, I can give you some info I hope will be helpful.
The pump/regulator screw on the bottom and the idle mixture screw on the carb have a great deal of overlap. All of the YSes up until the 120 AC version actually had no idle mixture screw, you just adjusted the pump pressure. Is your engine quiting suddenly, or does it burble rich? If the regulator is set lean and the idle screw compensates, then I can see the problem you describe. It's also possible for the opposite to be true: lean regulator abnd fattened idle.

Questions you need to answer for yourself ...
Can you reproduce this on the ground? (even after a short warm-up flight)
How does the mixture sound at 1/2 throttle? That will be dominated by the regulator, assuming the top end needle is set reasonably.
Have you checked the valve lash settings?

Hope this helps some,
	Dean P.

-----Original Message-----
From: discussion-request at nsrca.org
[mailto:discussion-request at nsrca.org]On Behalf Of Eddie Batchelor
Sent: Monday, June 28, 2004 11:34 AM
To: discussion at nsrca.org
Subject: YS dies at bottom of stall turn - Help!!


Facts:  YS110 powermaster 30% Heli fuel Ys glowplug APC 15X10 turning 8800
and idles between 1800-2000.
Problem:
My fairly new YS110 (about 2 gallons of fuel thru it) has started dieing at
the end of prolonged downlines -such as coming out of a stall turn or on
final approach.

I have done the following so far:
1. assumed the idle was rich - leaned it out until the motor started
throwing the prop. Ok now it's too lean, so I richened it back up.

2. changed the tank and fuel lines.

3. discovered one of the in-line fuel filters partially unscrewed. tightened
this up

4. changed the throttle servo that appeared to have deadband around the idle
area(apparent bad pot)

I've attempted to fly after each of these changes and the motor will die
when I add throttle at the bottom of the stall turn. Now if I give a little
throttle during the downline & not let the motor slow down completely it
appears to do fine.

I want to be able to do a stall turn or a big loop and let the plane pull
out at the bottom with the motor idling and continue flying (at idle) until
I wish to add power.

Another example is on a landing approach when you realise you're a little
short and try to add just a blip of power to reach the runway, it dies about
then. (has twice now)

Does anyone see a "glaring" mistake I'm making, or have a suggestion of what
next to look at. I realise I'm at the bottom of the learning curve with YS
4-c motors and it ain't no fun  :-))

Any help will be greatly appreciated.

Eddie

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