[NSRCA-discussion] YS140DZ idle question-answer

Tue Aug 1 07:42:00 AKDT 2006

There is no such thing as gravity, the earth sucks!

  There must be vacuum!

twtaylor <twtaylor at ftc-i.net> wrote:
  There is no such thing as vacuum on this earth. It's differential pressure.
:)

-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Grow Pattern
Sent: Tuesday, August 01, 2006 9:52 AM
To: NSRCA Mailing List
Subject: Re: [NSRCA-discussion] YS140DZ idle question-answer

It has to be in the plane :-)

The pumping action allows the tank to be on the CG just like the pressure 
systems.

Regards,

Eric.
----- Original Message ----- 
From: "John Ferrell" 
To: "NSRCA Mailing List" 
Sent: Tuesday, August 01, 2006 9:49 AM
Subject: Re: [NSRCA-discussion] YS140DZ idle question-answer

> How critical is tank location?
>
> John Ferrell W8CCW
> "My Competition is not my enemy"
> http://DixieNC.US
>
> ----- Original Message ----- 
> From: "Earl Haury" 
> To: "NSRCA Mailing List" 
> Sent: Tuesday, August 01, 2006 7:50 AM
> Subject: Re: [NSRCA-discussion] YS140DZ idle question-answer
>
>
>> Bob gets the award for proper description of the YS D engine series fuel
>> system. Yamada san is a very innovative designer!
>>
>> As Bob states - fuel is "sucked" from the tank on the pump piston
>> downstroke
>> (low pressure in the pump results in atmospheric air pressure "pushing"
>> fuel
>> from the tank). Appropriate inlet / outlet check valves within the pump
>> provide for incoming fuel draw or outgoing fuel injection.
>>
>> The pump is a positive displacement piston pump, ingeniously fitted into
>> the
>> intake valve pushrod which provides motion that is timed to the intake
>> stroke of the engine. The output of the pump is determined by pump size /
>> stroke and pump rate (engine rpm) - this output is controlled by the
>> needle
>> valve (high end) and the throttle barrel slot. As with all positive
>> displacement pumps transferring fluids (non-compressible), there must be
>> some way to accommodate excess volume (i.e. closing the throttle at high
>> rpm) or parts will break! A spring vs. fuel pressure against a diaphragm
>> regulator provides an internal return path from the pump outlet to the
>> pump
>> inlet - recirculating excess fuel. Another ingenious YS design 
>> application
>> is that the regulator spring pressure is modulated by crankcase pressure
>> (against the spring side of the diaphragm) - increasing pressure at high
>> rpm. Because of this - idle mixture can be changed by adjusting the idle
>> fuel pressure with the tension of the regulator spring. Of course -
>> changing
>> the spring tension also affects the high end pressure (CC + spring) and
>> must
>> be accommodated with appropriate needle valve changes.
>>
>> For those still convinced that the regulator on the front of the pump is
>> actually "the pump" - I suggest that you remove the crankcase pressure
>> line
>> between the regulator and the engine and run the engine (it'll lean out 
>> at
>> WOT but can be richened with the needle) - fuel will still be pumped just
>> fine!
>>
>> Earl
>>
>>
>>
>>
>> ----- Original Message ----- 
>> From: "Bob Kane" 
>> To: "NSRCA Mailing List" 
>> Sent: Monday, July 31, 2006 10:14 PM
>> Subject: Re: [NSRCA-discussion] YS140DZ idle question-answer
>>
>>
>>> No. The DZ series does not use a pressurized fuel
>>> system. The fuel is "sucked" from the tank by the fuel
>>> pump on the down stroke of the intake pushrod (valve
>>> closing), and "squirted" out to the injector as the
>>> intake valve pushrod opens the valve. The regulator on
>>> the front of the fuel pump limits the fuel pressure by
>>> opening when the fuel pressure is sufficient to
>>> overcome the spring tension in the regulator. The
>>> spring is much stiffer than the spring in the FZ/L
>>> series motors. There is no low end adjustment on the
>>> carb in the DZ series, so the regulator is used to set
>>> the idle mixture. Start the engine, set the high end
>>> needle as you would on any other YS, pull the throttle
>>> back to idle. If the engine slows down and dies, it is
>>> rich, turn the regulator out to lean it. If it speeds
>>> up and dies, it is lean, turn it in to richen it.
>>> Recheck the high speed needle.
>>>
>>> These engines will not tolerate restrictive fuel
>>> filters. I am currently using a Sullivan Crap Trap to
>>> keep the big boulders out of the fuel system and it is
>>> working well. I'm still playing with using a check
>>> valve on the vent side of the tank. It works well
>>> without it but I get some leakage out of the vent.
>>>
>>> I have recently been through an extensive learning
>>> experience with the pump system on these engines. If
>>> the fuel lines past the pump blow off the fittings,
>>> the pump regulator is set too rich or is sticking
>>> closed. If you are having trouble with the adjustments
>>> it might be time to have the pump/engine serviced.
>>>
>>> I will say the power of the 160DZ is incredible, way
>>> more than what is needed to pull my Temptation through
>>> the Masters sequence. I'm running an APC 18.1X10 prop,
>>> the thing pulls like a locomotive and slows down as if
>>> you threw the anchor out. Vertical uplines, even with
>>> rolls are just over half throttle. The only possible
>>> disadvantage is the prop is heavy and will probably
>>> cause more rapid conrod wear.
>>>
>>>
>>> --- vicenterc at comcast.net wrote:
>>>
>>>> Eric,
>>>>
>>>> I got a new YS 160 DZ. Is this procedure equivalent
>>>> for both engines?
>>>>
>>>> Thanks,
>>>>
>>>> Vicente "Vince" Bortone
>>>>
>>>> -------------- Original message -------------- 
>>>> From: "Grow Pattern" 

>>>>
>>>> Michael,
>>>> The big and first thing to remember is
>>>> that the DZ uses a pump. If you keep thinking about
>>>> the pump as a regulator it may not help you set your
>>>> engine. Unfortunately the instructions call it a
>>>> regulator. The fuel is metered out to the carb by
>>>> the pushrod action and the "pulsating" crankcase
>>>> pressure operates the pump side.
>>>>
>>>> The next thing is that the carb does two things. It
>>>> controls the air flow to the inlet valve and the
>>>> fuel supply to the injector. Even though the needle
>>>> effects all of the fuel flow it is not the right
>>>> thing to use to get a good idle. Many people
>>>> accidentally/unintentionally override the pump
>>>> settings with the main needle to get a good low-end
>>>> rpm.
>>>>
>>>> The "regulator" screw restricts the primary fuel
>>>> flow and is the one that you must use to set an idle
>>>> and transition. If you get the big brass screw set a
>>>> bit too rich it will keep dousing the plug,
>>>> especially at low rpm.
>>>>
>>>> The trick to a good setting is to keep closing the
>>>> pumped fuel supply until the engine will not run any
>>>> more.
>>>>
>>>> You do this by turning the big brass screw clockwise
>>>> about 1/8 of a turn and then start and warm up the
>>>> engine. Keep the main needle at about 1.5 turns or
>>>> more and don't worry if it runs a bit rich as you
>>>> open the throttle about half way, in short bursts.
>>>> Do this again and again until the engine will not
>>>> start or keep running at idle or open up.
>>>>
>>>> You are now very close. Turn the brass screw back
>>>> anti-clockwise about 1/8 of turn. and see if the
>>>> engine will start and idle. It should be able to go
>>>> as low as, and hold about, 1.500 rpm.for about a
>>>> minute. If the throttle smoothly increases the rpm
>>>> you have a good low-end setting. (Go more "open" on
>>>> the brass screw if it is needed to keep it running).
>>>>
>>>> Now is the time set your top-end needle. It may need
>>>> more or less fuel so please open up carefully and
>>>> listen for the warning "bark". Richen the main
>>>> needle if it barks. If all goes well, set the
>>>> high-end needle for max rpm and then richen it back
>>>> about 500 rpm.
>>>>
>>>> After that it should run like a Swiss-watch, start
>>>> better, and last a good while. It should not quit in
>>>> the air or on the ground.
>>>>
>>>> Please let me know if this worked for you.
>>>>
>>>> Regards,
>>>>
>>>> Eric.
>>>> ----- Original Message ----- 
>>>> From: Michael Cohen
>>>> To: NSRCA Mailing List
>>>> Sent: Sunday, July 30, 2006 2:31 PM
>>>> Subject: [NSRCA-discussion] YS140DZ idle question
>>>>
>>>>
>>>> OK list, I have a question for you. I have a 140DZ
>>>> that will not idle below 2300ish RPM. Richard
>>>> Lindberg and I have adjusted the regulator, but it
>>>> appears to have little or no effect. I might be
>>>> able to get one flight in, but eventually, on a down
>>>> line, it will die and 7 dead sticks are not that fun
>>>> to try. Full power seems to hold just fine. We
>>>> figured there might be an air leak, and that is why
>>>> it seemed to idle worse after a warm up flight, so I
>>>> replaced the valve cover gasket and the other
>>>> gaskets at the backplate, but that did not seam to
>>>> make a difference. Anybody got any ideas besides
>>>> the usual OS/Webra/Mintor/E-power/power slope
>>>> soaring comments?
>>>>
>>>>
>>>>
>>>> _______________________________________________
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>>>> NSRCA-discussion at lists.nsrca.org
>>>>
>>> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion>
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>>>>
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>>>
>>>
>>> Bob Kane
>>> getterflash at yahoo.com
>>>
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>>
>>
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