If your bike is still in stock configuration, Honda has already done the engineering that should allow you to drive anywhere in north america.
If your bike has components changed from stock, I.E. exhaust, air filter, then it would be helpful to know what your current combustion conditions are. Unless you have access to a dynomometer and accurate exhaust analyzing equipment, you’ll probably have to rely on reading your plugs. To get an idea of what to look for, look at this page:
http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.htmlFirst, all four of your plugs should appear the same. If not, you’ve got some fixxin to do. Next try to identify if your current run conditions are ideal, rich, or lean. Now record at what altitude, temperature, humidity, and barometric pressure these plug conditions should be associated. Next evaluate your expected route, record your highest and lowest expected coincident altitude and temperature, at least. If you can predict humidity and barometric pressure, too, that’s great.
A little background-
Ideal mixture requirements do change with temperature, humidity (RH = Relative Humidity), altitude, and local barometric pressure. High barometric pressure and low altitude, in effect, compresses the air. This means there is more oxygen available in the same volume of air. Therefore, the air/fuel mixture ratios needed for optimum engine operation very with altitude and barometric pressure. Humidity also has an effect, as the suspended water molecules displace oxygen on a volumetric basis. And, of course temperature's effect is that of expansion and contraction, whereby heated air has the molecules spaced farther apart, lowering the oxygen density per volume. The extreme conditions would be:
Low altitude, high barometric pressure, low temperature, and low humidity = greatest amount of available oxygen per volume of air.
High altitude, low barometric pressure, high temperature, and high humidity = lowest amount of available oxygen per volume of air.
Okay, get some graph paper and mark the high and low, altitude, baro press., temp, and expected humidity 11 divisions apart on four separate lines. (This is so you can divide the difference between the high and low numbers on each scale by 10 to easily fill in the scale markings.)
EG. 40 Degrees F on line one, 1st vertical bar, 100 degrees F on 11th
vertical bar across. Do the same for each of the others in turn.
You now have a graduated scale for each data collection. For the temp scale in my example, it is in 6 degree increments from 40 to 100. Do the same thing for the other three scales. But, since the baro pressure has an inverse relationship, make that one backwards in relation to the others, with the highest number on the right. Now on the scales you made, mark the conditions as data points on the scales under which your run time spark plug observations were made. With all four scales lined up atop each other a line drawn down the center of all four is the median ideal condition for your trip, and if your bike is tuned to that condition, you have the best chance of operating throughout the trip. Under these conditions the plugs should look like #14 in the spark plug reference pics. You’ll have to compare your plug conditions under your measured conditions to your expected run conditions and then determine if an adjustment is necessary to run the best for those conditions.
Isn’t that simple? But, wait there’s more.
Our bikes don’t have a rider controlled mixture control. They only have a throttle setting. The pilot adjust screws on the carb mainly effect the idle/low speed mixture in a limited range. While these are fairly easy to access, they don’t have a lot of influence over midrange throttle settings where the slide needle, needle jet, and emulsion tube air bleeds holes are the dominant mixture controllers. The main jets set the mixture for wide open throttle settings. None of these adjustments are very practical to change while touring.
A couple of points to consider.
If you are currently running lean at higher elevations, running at lower elevations could make the mixtures very lean. There could be some concern about over heating, pre-ignition, and even detonation, depending upon the severity.
Running rich at low elevations will be even richer at higher elevations. Power loss is expected not only from the rich mixture but lack of oxygen, too. The plugs may get fouled. You would be wise to carry spare plugs with you and the means by which to change them.
Lastly the charting exercise above points out extremes and the medium to those extremes. The scales have no weighting values. You may be willing to run too rich over some short, high elevation, portion of the trip in order to operate ideally over the longer portion of the trip. It is not recommended to run much too lean for very long.
Here comes the break to get over the reading fatigue :-)
Cheers,
