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

[Del Rykert]

Hi Urs..
     Being you can't richen your engine you definitely need to address that
part of the feeding problem. Removing pump from equation if tank is long run
to carb unless you raise tank above midline is only going to worsen you lack
of fuel. Do you have a engine stand to test in stand? I would do what Tony
suggested and then if that doesn't fix it try running on stand. I assume you
are using large enough diam. tubing to fuel carb. Don't mean to sound
insulting just trying all ideas of what might contribute to your dilemma.
    Please let us know how it goes.

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


----- Original Message ----- 
From: "Urs Baertschiger" <ursbaertschiger at hotmail.com>
To: <discussion at nsrca.org>
Sent: Saturday, November 29, 2003 2:22 AM
Subject: Re: Engine runs lean, old Webra 61. Who can help?


| Many thanks to all who replied.
|
| Del, I run the engine with fresh fuel. 5% nitro, 17% aerosynth oil. For
the
| test runs I didn't fit the cowl in order to be able to notice fuel
foaming.
| No fuel foaming noticed.
| It goes lean right after I open full throttle. Maybe the first second it
is
| OK, but can't say for sure as also my hearing needs a second to adjust. I
| checked the temperature by touching the head after the runs. It dosn't
seem
| to get too hot.
| No significant varnish build-up on piston and head. Barely visible varnish
| on piston.
| No, I can't get the engine slobbering rich even with needle valve backed
out
| until it almost falls off.
|
| I will check for restrictions in the fuel line once more.
|
|
| Tony, even though I know this carb rather well and had many of them
| disassembled, reassembled and adjusted many times over the past 20 or so
| years, I will follow your instructions regarding the basic set up. Also I
| will install a new Enya #5. - I don't know anything about the machined con
| rod and the company called "RPM". Where is it located? Somewhere in
Europe?
| - We too had problems with the con rod at that time, but as we started
using
| bigger props the problem went away. Seemed to be related to high revs.
|
|
| Karl, I will get the crankshaft out and check the bearings. - I thought
| about this too, but I cannot notice any rough spots or excessive play when
I
| turn the crankshaft, neither do I realise any hickups in the air when
flying
| the plane. Years ago I always realised while flying when a bearing was due
| for replacement, but this time I can't notice anything unusual. You sure
are
| right with your statement, that bad bearings can cause many kinds of
| problems as we too have come to learn over the years. Latest experiences
| gained with the OS 140 RX support these findings.
|
|
| Again many thanks for the help.
|
| Urs
| NSRCA #3069
|
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