Engine runs lean, old Webra 61. Who can help?

[Karl G. Mueller]

  Urs,

  One thing that nobody recommended yet in their replies was to check the
bearings. If the engine has not been run for a while than the chance of
having some spots (maybe rust?) in the bearing races that could cause the
lean runs. It might sound strange but
  bad bearings can cause all kinds of problems. Check for wear as
  well.

  Karl G. Mueller
  kgamueller at rogers.com

  ----- Original Message ----- 
  From: "Urs Baertschiger" <ursbaertschiger at hotmail.com>
  To: <discussion at nsrca.org>
  Sent: Friday, November 28, 2003 3:29 PM
  Subject: Engine runs lean, old Webra 61. Who can help?


  > Hi all,
  >
  > I very much would appreciate any advice that could lead to the solution
of
  > the said problem. -
  > Recently I got an old pattern bird out again after storing it for a
couple
  > of years. I didn't fly it no longer due to a persistently lean running
  > engine, a Webra 61 ABC rear exhaust. Had some spare time and thought I
could
  > find the reason for the lean running. However, all my efforts didn't
show
  > any noticeable improvement. The engine is equipped with a fiber glass
pipe
  > (Hatori copy), a pump and the Webra Dynamics slide carb with remote
mixture
  > control.
  > I made the following changes or adjustment, always one at the time. All
test
  > runs on the ground, no flying:
  > 1) Checked tank, all fuel lines including fuel pick-up. Checked also for
  > kinks in the lines.
  > 2) Disassembled, cleaned and checked carb.
  > 3) Bypassed pump.
  > 4) Changed plug from Enya #5 to OS - F.
  > 5) Extended pipe length by 1".
  > 6) Tried different props. Instead of 12x10.5 I tried 11x11 and 12x10.
  > 7) Changed carb.
  > 8) Changed pump setting.
  >
  > What else should I check? - Apart from the usual replacement of bearings
and
  > occasionally a piston/liner set the engine was running perfectly for
several
  > hundred flights before this problem appeared.
  >
  > Many thanks in advance for any advice.
  >
  > Kind Regards
  >
  > Urs
  > NSRCA #3069
  >
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