Received-SPF: none
 receiver=logan.com; client-ip=24.201.245.36; envelope-from=geryvon@videotron.ca
Date: Sat, 04 Jun 2005 17:36:53 -0400
From: =?iso-8859-1?Q?G=E9raldine_Berger_&_Yvon_Cournoyer?=
 <geryvon@videotron.ca>
Subject: BAR GRAPH AIR/FUEL GAUGE
To: Rotary motors in aircraft <flyrotary@lancaironline.net>,
 ACRE <rotaryeng@earthlink.net>
Reply-to: =?iso-8859-1?Q?G=E9raldine_Berger_&_Yvon_Cournoyer?=
 <geryvon@videotron.ca>
Message-id: <000201c5694d$b18b6cb0$47228242@AMDSEMPRON2400>
MIME-version: 1.0
Content-type: text/plain; format=flowed; charset=iso-8859-1; reply-type=original
Content-transfer-encoding: 7BIT

   I fly a Zenair Zenith 200 with a l986 13B.  I have installed a 
Cyberdyne Instruments bar graph air/fuel gauge (P/N 7009). The O2 sensor 
is located ~31 inches from the exhaust ports. The O2 sensor is not a 
Cyberdyne Instruments part. It is an aftermarket universal single wire 
sensor. The readings of the air/fuel gauge are baffling me. At idle of 
1100  rpm and MP of 14.1-14.2 inches/mercury, the air/fuel gauge shows a 
rich condition of ~12.7:1. That is where the engine runs best at idle. 
At full power static of 5200-5250 rpm and MP of ambient (~30 
inches/mercury), the air/fuel gauge reads rich ~13.2:1. However, when I 
retard the throttle to 3000-3500  rpm, at a MP of 17.0-17.1 
inches/mercury, then the air/fuel gauge reads lean at ~16.0:1. The 
engine runs quite evenly at all power settings but I wonder if the 
variations in fuel mixture are normal and safe?
Yvon.