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RE: CO adjustment



> -----Original Message-----
> From: owner-st@xxxxxxxxxx
> [mailto:owner-st@xxxxxxxxxx]On Behalf Of David
> J. Hughes
> Sent: Monday, February 14, 2000 2:07 AM
> To: ST@xxxxxxxxxxxxxx
> Subject: CO adjustment
>
>
>
> Hi all.
>
> Can some kind soul give me the run-down on what the CO
> settings are all about.  I'm working on the assumption
> that it's Carbon Monoxyde related (my high school
> chemistry teaching girl friend would be proud of me ;-).

It is. The CO level directly correlates with the amount of excess
fuel being injected into the engine.

> . If that's the case, how does the EMS come into play
> with relation to generation of CO?

The fuel injection systems on most Sprints (i.e., the ones *not*
sold in Germany) use an open-loop system. Open loop fuel injection
systems use a digital map to determine how much fuel to inject
based on engine RPM, throttle setting, and air pressure.
Unavoidable variations in manufacture can cause this map to inject
either too much or not enough fuel. Too much fuel causes the
bike's fuel consumption to increase, robs power, and can cause
backfiring. Too little fuel will also rob power as well as
increasing combustion chamber temperatures and making the engine
run too hot. If you go to far either way (too much or too little
fuel) the bike may not run at all or will run poorly.

> . Is this an unused fuel issue related to emission
>   control requirements or is it engine performance /
> efficiency related?

All three. If the CO is too low the bike won't run right. If it's
too high it will waste fuel, dirty up the atmosphere, and not run
right.

> . Why do the settings need to be tweaked based on your
> exhaust setup (better flowing exhaust pulls more fuel straight
> through the head maybe)?

Changing the CO setting alone won't compensate for the different
flow of a modified exhaust. For that you need a different map.
Once that new map is downloaded you need to re-adjust the CO
level, of course, but it's the new map that does most of the work.

Closed-loop systems don't need the CO set (and can use a simpler
map) because they measure the oxygen content of the exhaust in
real-time and use that to adjust the amount of fuel injected.



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