I'll post this in Equipment as well but its a question I have had for a bit. While looking thru Arch's stuff I came across this at Sudco:
(editor's note: HTTP tag is correct... why doesn't it load the pic Arch?)
K&N Air/Fuel Monitor
The K&N Air/Fuel Monitor is a precision instrument designed to aid in making correct jetting decisions. The monitor measures the oxygen content of the exhaust gas and displays the relative air/fule ratio information on an LED display. This device is an economical way to analyze exaust gases, enabling a tuner to see at a glance what the Air/Fuel ratio of an engine is at any RPM or throttle position. Can be mounted on bike for perminent installation, or used temporarily during tuning.
Order No. 005-200
Anyone have any experience with one of these? I think I am interested. Alternatively, this looks like a pennytech solution also on the Sudco page:
Sudco/Mikuni Pocket Carb Tuner
A handy pocket-size slide calculator which can be used to determine required jetting changes in Mikuni carburetors due to ambient temperature, altitude, or both. It also provides a guide for determining rich or lean carburetor conditions. The Pocket Tuner is applicable to both single and multi-carburetor applications on two stroke and four-stroke engines.
Order No. 002-430