I have received various questions over time on how to best map a YCCT (or similar throttle by wire system) motorcycle on todays dynos.

The biggest issues that folks are fighting with is the fact that 100% open throttle only happens when the ECU wants it to happen. For the VMax that means that at 4,000 rpm (just an example) you only get a partially open throttle, an 09 R1 does the same thing not only at low rpms but also above 11,000 rpms.

If you are using a PCIII USB the dynojet software allows you to record the throttle position within each dyno run. The PCV is to this date not yet supported as a data acquisition unit for Winpep.

Even with the PCIII USB that records the true throttle position of the YCCT into the dyno run data, mapping a custom fuel map can be tedious to say at least. Especially in those transitional rpm segments where the ECU decides to slowly increase or decrease throttle opening angles.

What works best for me is a very simply and straight forward process of mapping multiple segments at once. By the way, You rarely have the need to switch to 250 rpm segments on the Power Commander, it is usually total overkill that does not buy you any extra performance and takes a lot longer (2x) to custom map. A YCE ECU (Yamaha Race ECU) e.g. for the R1 only allows settings for 1k rpm increments and that still gets you very close to perfect in terms of power and torque.

The multi segment mapping approach. 

If you map the full throttle range of the bike (I usually start with that after some initial tests and very basic adjustments) I recommend slowing down the acceleration of the bike with the Eddy Current Brake. The VMax needs as much as 70% brake to get good clean readings. The slower the acceleration, the cleaner the AF readings for each rpm segment. An R1 only takes about 50% of breaking initially. Once the basic map is done you can reduce the breaking to see how the difference in load changes the map and make adjustments.

To perform the multi segment mapping, simply perform a couple sweep runs at set breaking power and record the data, including rpm and AF. usually it takes 2-4 runs for the AF ratio to settle in and become repeatable. This very much depends on temps and the bike.

For the VMax start the mapping at 2500-3000 rpm, depending on when the 'clean' - non - 'fuel accelerator pump' - readings set in (Yes most Yamaha ECUs will have a similar accelerator pump or acceleration enrichment feature for the first moments after twisting the throttle).

With the data collected adjust each Power COmmander segment by as many clicks as you are away from 13.2:1 (this is just a good starting point - not necessarily the final AF). So a reading of 12.2:1 should lead to a -10 and a reading of 13.8: should lead to a +6 setting in the fuelmap.

Depending on the bike you might 'overshoot' the desired AF ratio and if so, will have to cut the corrections in half the next run you perform.

The multi segment approach is about entering the same value into the 40, 60, 80 and 100% segments of the fuel map for the desired rpm range. Again this is just the initial full power map. Doing so will eliminate the need to check the throttle position at every rpm segment. 

Map the entire fuel map like that. In the end you should have a clean 100% applied throttle run. Once you are done, you perform the same for 80% throttle but leave the 100% segments untouched. Again the Eddy Current brake comes in very handy if you want to hold lets say 4,000 rpm to set to 60% throttle and then release to perform the actual run.

You will also find that the identical settings make for a very good starting point for the 80, 60 and 40% segments as neighboring segments usually are within very close settings.

At 500 rpm increments this should take less than 1h to complete, for 250 rpm increments it can quickly take 2h as twice as many segments have to be mapped. I usually start with 500 rpm increments and convert the map to 250 rpm increments if I see a need for that based on uneven fluctuations of the fuel map that cannot be solved in 500 rpm increments (this is rare).

To finish out the map (mainly at 80 and 100% throttle) you now check to see how optimal the 13.2:1 AF ratio really is. If you don't have a torque converter setup, the best way to test that is to go into the Power Commander Cylinder Trim, and raise all 4 cylinders by 5 %. Perform another set of runs and see what changed. The set the trims to -5% and perform yet another set of runs.

With these results you will see what rpm segments of the map benefit from leaner or richer fuel maps. adjust accordingly, rerun the tests for a new baseline and perform the trim test once again - do as long as the power figures are no longer increasing. 

BTW: When I talk about power figures, I do not refer to the Peak horsepower but rather to the horsepower at each rpm segment. 

Now if you have a couple extra hours, you should install cylinder individual mapping ports and perform the mapping per cylinder. Seeing differences of up to 2-4% in fuel mapping by cylinder can net in a few extra hps.

I could go on for ours, but this is a good start to get you going or to help a dyno technician who has not dealt with YCCT before to get started.

May you end up with the most power of all!

fxstein