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

[Del Rykert]

Two things you didn't mention was trying a new fresh purchased fuel, and
Check for foaming fuel in tank.  How long before it goes lean? Does the
piston or head show varnish? Can help it over heat and go lean. My webra
with Dynamix carg always ran best on low nitro fuel. Nitro is very expensive
and hard to come by in Europe and that engine was designed with that in
mind. Can you get the engine to go slobbering rich with backing out needle
valve? If not you still have a restriction in feed line. Any bubbles noticed
in fuel line near carb would note foaming and also needs to be fixed.  Hope
these ideas help.

     Del K. Rykert
     AMA - 8928
     NSRCA - 473
     Kb2joi - General


----- Original Message ----- 
From: "Urs Baertschiger" <ursbaertschiger at hotmail.com>
To: <discussion at nsrca.org>
Sent: Friday, November 28, 2003 12:29 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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