The operating system in the computer is similar to DOS in your computer, but in these units it comes in a .hex file, so it is called the ‘OP CODE’ or the HEX CODE’. The computer actually does very little computing. What it does do is get inputs from the sensors on the motor; air temperature, coolant temperature, air pressure, crankshaft position, throttle opening in %. It calculates engine speed based on the last few crankshaft positions, then uses this calculated RPM and the throttle opening to find a value for fuel delivery and spark advance from a look up table; commonly called a ‘MAP’. The value that is looked up in the map is then adjusted for the other variables (temps and pressure). This is done for every engine cycle, and when the time is right, the fuel injectors are opened for the appropriate period of time, and the ignition is fired at the precise moment that it is needed. Then the cycle repeats.
The D&M kit is the owners tool that allows you to fiddle with this stuff. You will be doing your jetting with it, you can troubleshoot with it, and you can change maps with it. Here is a spreadsheet (thanks, Radical Ron!!) that details what the maps look like. It includes 3 maps, that of the E, C, and X model motorcycles. And if you like that kind of stuff, here is a spreadsheet that compares the C and E maps. The fuel delivery is identical, and not charted here. The only difference is the ignition advance, which is detailed and graphed. There is no difference at all from 75% throttle and up, and above about 4500 RPM. The picture at the right is a chart of the ignition difference between the C and E. Note that the chart covers only rpm range of 1200 to 6200 rpm, there are no differences outside of this zone. What this means is that the E map will give you all of the power the C map will, but with smoother response at the smaller throttle openings.
So, without consideration of the throttle sensitivity, there are basically two maps from the factory; the X/S maps, and the C/E maps. The X/S are pretty easy off the bottom, then rage out to the limits of the motor. The C/E map is most powerful at the lower RPMs, then much more mild up on top to conserve fuel and to be easier to ride on the longer cross country races. The C is slightly more aggressive below 4000 RPM and below 65% throttle opening for the dryer cross country races. The X/S, E, and C maps are all available at ‘Cannondaler.Com’ with T/S settings from 110 to 150 in steps of 10.
The next step, then was to fiddle with the maps. The chart you see to the right is a graphic representation showing how much fuel is delivered at what RPM for the two basic map types. The ignition curve in each map is optimized for the amount of fuel that will be delivered.
The first breakthrough was when Radical Ron put together an experimental map for me, the HarryMoto Combo map. I asked him to try the E map up to 4000 RPM, and then patch in all the numbers from the X map. Combined with the T/S of 110, this is the most aggressive map for the ‘dale. Later on GP suggested using the C map for the bottom end, and the GP Combo map was born. The combo maps are identical at wide open throttle, but the GP map is slightly more aggressive below 4000 RPM and below 65% throttle opening. Loading a map takes about two minutes with the D&M kit, so it shouldn’t be hard to plug in some maps and see what you like. The combo maps are also available at ‘Cannondaler.Com’, free for the downloading.
Additionally, if you wish to help preserve your Cannondale crank for the duration of your ownership, here are links to the '10k' maps. These are the HarryMoto Combo maps with the rev limiter set to 10,000 rpms. This matches the design limit of the stock bearings. <Note: it turns out that the 10K rating on the bearings is in GREASE, not in an oiled application. I still run a lowered rev limit, but I'm using 11K now.> The factory rev limiter setting is 11,800 rpm.
HarryMoto Combo 10K 110 HarryMoto Combo 10K 120 HarryMoto Combo 10K 130 HarryMoto Combo 10K 140 HarryMoto Combo 10K 150
And one more map that I made for my daughter, the 'Amber Moto map'. It's the leanest part of the two maps above with the rev limiter set at 7000. It's still a handfull for young riders, but more managable and the ridiculous rev limit keeps the speed from building too quickly if things get out of hand. It's terrible to ride, you hit the limiter as soon as you twist the throttle! Amber Moto Combo 7K 150
To actually jet the thing, you can set the idle to 2100 and then note the throttle position. Adjust the offset by .1, then set the idle again and note the throttle position. The offset setting that gives you the lowest throttle position to maintain 2100 RPM is the optimum idle setting. You might go back .1 richer from there to get a more steady setting, like we used to do when we were turning pilot screws and changing pilot jets.
To adjust the main jet, so to speak, you will have to resort to the WOT runs and then read the spark plug. Not fun, as the spark plug is pretty far down in there. Sort of makes you miss the old two-stroke, getting that spark plug out! The tricky part here is that the flow effects the offset a lot, and the offset effects the flow a little. You can do the main jet first, and minimize the effects of the second adjustment. You can also use the spreadsheet to see exactly what effects the adjustments will have.
Here is an example shot of the flow/offset spreadsheet. In this example the flow was 2400 from the factory, and the offset was .70. The bike in the example has had the flow set to 2350 and the offset set to .6. The original fuel delivery would be on the 100% line in the middle of the chart. The effect of each change is charted, so you can see that the offset is a non-linear function and the flow is quite linear. Another important thing to consider is that the effects are not based on RPM, but rather on the length of the injector pulse in milliseconds. It's not quite the same, check the example above to see the injector times at different RPMs.
You can download the spreadsheet to get a look at the changes you are making to YOUR bike and the effect they have on the mixture in different areas. Just input your flow/10 (as in the example, 2400/10 = 240) and the offset. There are also blocks for the flow and offset you are considering, the ones with 0.6 and 2350 in the example. The chart shows the difference between what you input originally and what you input as the new settings. Remember that the original settings are represented as the 100% line, and the changes are shown in percent from that baseline. Good luck, and use your common sense; it you run it too lean, you WILL burn it up!!
Tap and Die #'s
For those of you who have actually made it this far, here is a spreadsheet that details what drill to use when you have to make a threaded hole. I've found it to be very useful!