YS 91AC

[Ken Thompson]

Bill,

I'm not sure on the valve gap checking, on a motor this small.  We used to check our valve backlash and rocker clearance on our engines years ago, but this was running fine and then quit.  I do have a little play in the exhaust valve, and none in the intake valve.  That leads me to believe I have a problem in the head somewhere.  I have a spare jug but it has a leaky valve also, that's why I think I should just send it in.

Ken
  ----- Original Message ----- 
  From: William C. Harden 
  To: discussion at nsrca.org 
  Sent: Wednesday, June 01, 2005 8:28 PM
  Subject: RE: YS 91AC


  Ken,

   

  Do you know how to check the valve gap?  Your problem could be that one of the valves is not completely closing.  If this is the case, then it could be either carbon build up on the underside of the valve, or that the valve gap is too small (maybe none at all) and the valve never completely closes. 

   

  Also, I have seen glow plugs blow apart and there is hole in the plug itself.  

   

  Hope you solve the problem.

   

  Bill

   

   

  -----Original Message-----
  From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org] On Behalf Of Ken Thompson
  Sent: Wednesday, June 01, 2005 7:05 PM
  To: discussion at nsrca.org
  Subject: YS 91AC

   

  Hi all,

   

  I have a YS-91AC that came in a plane I aquired last weekend.  On the 16th flight I lost the motor about 2 minutes into my routine.  After a safe, and pretty nice landing, I might add, I brought it back to the pits to see what happened.  I could turn the prop by hand with almost no back-pressure.  

  I pulled the motor out when I got home and checked it out the best I know how.  Pulling off the backplate I see the connecting rod and piston seem to be OK and the valves seem to be moving like they're supposed to.  I don't know a lot about these engines, as this is the first YS I've run in a plane. 

   

  What I need to know is where is the best place to send the motor to be checked out and re-built.  I don't want it just patched up, I would like it done right, but a quick turn around.

   

  Asking too much?

   

  Thanks in advance,

   

  Ken Thompson

   
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