[NSRCA-discussion] YS140DZ idle question-answer

[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?


------------------------------------------------------------------------------


  _______________________________________________
  NSRCA-discussion mailing list
  NSRCA-discussion at lists.nsrca.org
  http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.nsrca.org/pipermail/nsrca-discussion/attachments/20060801/c0907516/attachment.html