YS 91FZ problems still

[Grow Pattern]

G'day Blue,
                  Spent a bit of time on the old YS 91, the new YS 91 and then the YS 110. The later models use a one-piece regulator/diaphragm gasket.

After a bunch of bad runs and the occasional prop spitting episode etc. I found the gasket to be distorted. Unfortunately, you can't just put a regular diaphragm and leak-free in its place. The regulator housing is machined different and has a sort of taper inside it where you would normally seat a diaphragm.

The answer was to fit a used regulator from a YS 1.20 (1.40's are the same). New gasket and regulator and Hey Presto! a new engine. Did it to both a 91 and a 110. Same very pleasing results on both.

Ref. The orange O-ring perishing. Never seen that before. I have seen some get cut up by the threads. I wonder if it at some time got very hot in your climate?  If you have some spare heat send some up here please :-)

Regards,

Eric.
  ----- Original Message ----- 
  From: Dean & Melissa Williams 
  To: discussion at nsrca.org 
  Sent: Thursday, December 16, 2004 5:56 PM
  Subject: Re: YS 91FZ problems still


  Hi
  Tom Koenig and Peter Pennissi are about three thousand kilometres away but I will get in contact with them for some support.
  I did dismantled the regulator after I noticed some leakage from around the adjusting screw and found the O ring is split .
  I am going to order a replacement as well as a diaphragm just in case.
  As to the over heating the motor is in the plane with no cowl , so it is like it is on a test stand fully open and it was running great before , there are no signs of heat on the case and the motor seems fairly cool compared to the two strokes I run by feel ( I have not got an temp gun but I can get one , what temp should it approx be? ) 
  One extra question is the O ring neoprene as it is an orange colour but still seems to been eaten by the fuel very brittle and split ?

  Thanking everybody for their help
                                                Dean (outback OZ)
    ----- Original Message ----- 
    From: Rcmaster199 at aol.com 
    To: discussion at nsrca.org 
    Sent: Friday, December 17, 2004 1:22 AM
    Subject: Re: YS 91FZ problems still


    Dean, you have several Pattern people in Australia, and a couple of them, Tom Koenig and Peter Pennissi are regulars on the Discussion board. Their addresses are as follows:
    Tom.Koenig at actewagl.com.au and Peter.Pennisi at publicworks.qld.gov.au.

    Try and see if either one is close enough to get you some direct help

    good luck, and happy holidays

    Matt Kebabjian
      From: Dean & Melissa Williams 
      To: discussion at nsrca.org 
      Sent: Thursday, December 16, 2004 1:40 AM
      Subject: YS 91FZ problems still


      Hi 
      This motor was running great at last after my idle problems thanks to you guys (fix them by sanding the rocker cover) was getting 9000 rpm top end and 2100 rpm bottom end with A 14x 10 with a20/20 this is a new engine. 
      The plane has still not been in the air. 
      the engine has had about 5l of fuel through it. 
      The problem now is it starts runs up and tunes out to 9000rpm and runs for about 1 to 2 min. and then starts to surge and goes off tune with air bubbles in the fuel line from the regulator. 
      Please help as I am from the outback of Australia and have no assistance out here. 

      Thanking you 
      Dean (outback OZ) 
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