Changing the FJR's CO Settings
Tom Barber (aka Barbarian) and Dwayne Verhey (aka Torch)
from the FJROwners online forum
figured out how to enable a North American spec'd
FJR1300 to have it's EFI's CO setting adjusted, like the European and OZ/NZ
On 03/05/03 Torch provided the following text and photos
[minor correction on 04/16/03]:
Note: if you have a North American FJR, you'll need to do the
Barbarian Jumper Mod before you can
make the adjustments described here...
Ok, so you followed all the directions from the
Barbarian Jumper Mod page and
are anxious to try it out.
and hold both Select and Reset while you turn on the key. Do not release
the buttons until you see the Diag screen appear. (about 8-10 seconds)
Now, press Select once to toggle to the CO mode.
Press both Select and Reset together. Hold for about 2 seconds to enter CO
mode. The number displayed is the cylinder selected. Press Select to scroll
up from 1 to 4. Pressing Reset scrolls down.
Press both buttons simultaneously for a few seconds to see the setting for
the selected cylinder. It will be between -126 and +128.
Write this number down and keep it in a safe place forever. If you decide
to play around and screw something up you will then be able to return to
The number is a factor that is used by the fuel injection system to
compensate for manufacturing tolerances. It will be different for each
cylinder. It is not a direct measure of the CO percentage of the exhaust
gas. There is no way to predict the CO level from this number. A CO sniffer
must be used on each header pipe (which means you must install a riv-nut on
each pipe first to sample from). Then this adjustment is used to bring the
CO levels as shown by the sniffer to specification (3-4% at idle)
Pressing Select will increase the value (richen the mixture),
pressing Reset will decrease it (lean the mixture). Pressing both
buttons simultaneously will back you up to the previous "menu" and
allow you to choose another cylinder.
To exit CO mode, turn off the ignition key.
A relatively affordable portable exhaust gas analyzer (EGA)
is available from
The "Rivnuts" mentioned above are available from
Bollhof Technology --
you probably want the "Rivnut EZ" version.
Rivnuts are also carried by Snap-On
dealers, by J.C. Whitney
and by Princess Auto in Canada
(where they're called "nut inserts").
Be sure to use anti-seize when you put the bolts in the Rivnuts as the
exhaust gases and heat can make them rust quickly.
On 03/06/03 Barbarian
wrote this followup message:
I spent some time searching the Web for information that would put the
numbers into some perspective. The MCNews article from last July claims
that the default setting
(for the NA-spec FJR1300) is 1.5% CO but that it runs best at 4.0%. From
some of the Web sites that I found, it seems that 1.5% is pretty much at
the rich end of the range for modern cars with FI and cats with O2 sensors.
On the Colorado site run by the emissions authority, for cars made prior to
'82, the limits range from 1.5% for cars made in '81 to something a greater
than 5% for cars made in the early '70s. It therefore seems likely to me
that the FJR, or any engine for that matter, would give better performance
and also run cooler at 4%. I can rationalize the emissions increase away
for several reasons: fewer bikes, smaller displacement, and way fewer
What I am not so sure about is whether that richer setting might allow
deposits to build up inside the cats causing them to eventually become
clogged. Perhaps one of those infrared temperature sensors could be used to
monitor the temperature of the cats over time and that might give early
warning of clogging because if they get coated on the inside, the oxidation
of the HC and CO will diminish or cease and the temperature of the cat
should drop correspondingly to the same temperature as the pipes upstream
of the cats.
Torch replied with:
There are two different CO readings that are used. The first is with the
Rivnuts (before the converters) and done with the air injection not
operating. Factory spec is 3% to 4% CO. The second is at the tailpipe
(after cats) with the air injection running. That is the 1.5% one. MCN
may have confused apples with oranges.
However, they might just be right. Fastwally was able to do his before the
dealer shut him down. If you check the FJROwners archives, initially he bumped
them all up 5 points, which took out the lean surge and helped performance
slightly. Then he installed Rivnuts and put his on a dyno. He found it
ran best after increasing the setting 7 points on each cylinder. He said
that brought his CO up from 1.3% initially to 3.4% on the low end. He
didn't specify the midrange starting point, but said it was spot on 4%
after for an increase of 4hp. I am assuming that the dyno numbers are in
comparison to stock trim, not in addition to his initial 5 point bump.
Meaning of course that you can have your cake and eat it too: 4% at the
headers is within spec and should only translate to 1.5% out the pipe.
BTW: HMarc brought up fuel efficiency, and Fastwally said he didn't notice
a substantial difference. Which makes a certain amount of sense -- if you
go too lean fuel efficiency will begin to suffer.
Copyright © 2003, by H. Marc Lewis, Tom Barber, and Dwayne Verhey.
All rights reserved.