[NSRCA-discussion] YS-160 setting

[Troy A. Newman]

Mark,

Leaning the pump+allowing more Bypass and equals less fuel to the engine 
hence leaner mixture will tend to require a HS needle change. Usually open 
it a little. What you have to realize is all the fuel gets pumped, then 
metered by the HS Needle, so the mixture on the HS needle will be set for 
high power and will be fine but when it goes to idle the fuel is still being 
metered the same way. Obviously the need is lower but he pump is still 
pumping the same amount. So at idle the flow that bypasses increases because 
of the way the pressures are applying to the little diaphragm from 
internally in the engine, Crank case. This pressure gets to the pump via the 
little fuel tube down to the cam gear area, and also up through the center 
of the pushrod tube.

So a pump adjustment will affect the HS needle for sure. Sometimes if I need 
to lean the pump and lean the HS I will just do the pump and see what 
happens. Because doing the pump means I leaned both.

Once you get it set correctly there is a pretty broad band. namely the HS 
needle has a wide range and folks try to set it on the rich side to be safe. 
I will run them just about 200-300 back of peak. You can't really set it by 
ear. Or I can't I'm deaf from running electric models last year  <SMILE>

Jason probably ahs the same issue. <SMILE>

Troy



----- Original Message ----- 
From: "Mark Hunt" <flyintexan at houston.rr.com>
To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
Sent: Thursday, March 08, 2007 10:05 PM
Subject: Re: [NSRCA-discussion] YS-160 setting


> Troy,
>
> Will this "leaner" bypass adjustment cause a need to adjust the high 
> needle
> in the rich direction?
>
> Thank you for the explanation.
>
>
> -mark
>
>
> -----Original Message-----
> From: nsrca-discussion-bounces at lists.nsrca.org
> [mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Troy A.
> Newman
> Sent: Thursday, March 08, 2007 9:34 PM
> To: NSRCA Mailing List
> Subject: Re: [NSRCA-discussion] YS-160 setting
>
>
> Jas,
>
> lean the pump a little bit about 1/4 turn and see if the motor starts to 
> go
> lean in the transition.
> The way this engine works is the pump pushes the same amount of fuel all 
> the
> time. Every stroke it pushes the same volume of fuel. If the engine is at
> idle and not using the fuel then pressure builds up in the injector line
> until it gets to that magic pressure where the pump pressure screw allows 
> it
> to bypass back to inlet of the pump. So everything the engine doesn't need
> gets pushed back around to the inlet of the pump for the next gulp.
>
> If you are at idle, and the pressure control on the pump is too tight
> meaning not allowing enough to loop back around it will got in and get 
> burnt
> and come out as lots of smoke at idle. Yet when you are at full power or 
> at
> least upper end power the HS needle is set and the mixture is correct.  So
> what is happening is you have too much going to the engine and not enough
> bypassing around.
>
> Lean the pump...CCW. If you get to lean on the pump is will start to
> detonate on throttle up or will sit and surge at idle. To be honest the 
> pump
> setting are actually pretty broad and the engine will run correctly with
> many different setting. The key is the pump always moves the same amount 
> of
> fuel. You are not adjusting pump pressure, you are adjusting the pop off
> pressure. Meaning the pressure which the little diaphragm will allow fuel 
> to
> loop back to inlet. So adjusting the pump richer means more pressure on 
> the
> spring and diaphragm so the pressure it takes to allow bypass is higher 
> and
> as result more fuel goes to the engine. Less spring pressure on the
> diaphragm and the lower the pressure in the injector line needs to be to
> allow the bypass and the less fuel goes to the engine because the little
> pressure valves open sooner.
>
>
> If it always pumps the same volume of fuel, and more is going to the 
> engine
> it will burn and turn to smoke especially at idle and below 1/3 throttle.
>
> Now that explanation was for everyone else. Here is the Jason answer.
>
> Turn the little brass screw on the front 1/4 CCW and see if it helps! if 
> it
> surges at Idle you went too far.
>
> Troy
>
>
> ----- Original Message -----
> From: "JShulman" <jshulman at cfl.rr.com>
> To: "NSRCA" <nsrca-discussion at lists.nsrca.org>
> Sent: Thursday, March 08, 2007 5:06 PM
> Subject: [NSRCA-discussion] YS-160 setting
>
>
>> Hi all,
>>
>> I've got my friends DZ and the high end needle is 1 1/8 turns out. The 
>> reg
>> is somewhere around flush. It smokes and bunch, smooth transition, but
>> 20ozs
>> in less than 8 minutes if I'm not careful. I remember hearing (being 
>> told)
>> that there is a less consuming set-up that I haven't done yet. Anyone 
>> know
>> what it is? Gonna fly again tomorrow and try it. Thanks.
>>
>> Regards,
>> Jason
>> www.jasonshulman.com
>> www.shulmanaviation.com
>> www.composite-arf.com
>> --
>> No virus found in this outgoing message.
>> Checked by AVG Free Edition.
>> Version: 7.5.446 / Virus Database: 268.18.8/714 - Release Date: 3/8/2007
>> 10:58 AM
>>
>>
>> _______________________________________________
>> NSRCA-discussion mailing list
>> NSRCA-discussion at lists.nsrca.org
>> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>>
>
> _______________________________________________
> NSRCA-discussion mailing list
> NSRCA-discussion at lists.nsrca.org
> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>
>
> _______________________________________________
> NSRCA-discussion mailing list
> NSRCA-discussion at lists.nsrca.org
> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>