Ed pulled our Road King onto...
Ed pulled our Road King onto his Dynostar dynamometer and prepped it for our first dyno run. We've loaded the Yuill Bros. base calibration file. We were pleasantly surprised by the performance of the vendor supplied EFI map.
Last month we covered installing a Yuill Brothers Stage 2 Kit on our 2007 Road King Custom. This month we'll explain how we tuned the bike and report our performance results. Plus we'll look at a self-tune versus a custom dynamometer tune.
You'll recall that the Yuill Brothers Kit included a high flow air cleaner, exhaust system, gear driven cams, and a MasterTune TTS ECM reprogrammer. After installing all the parts, we used the TTS to reprogram the stock ECM with a Yuill Brothers supplied TTS base calibration file (YA179000.MT7). Then we hauled the bike to The Dyno Difference in Dallas, Texas, where owner, Ed Dahir, spent the day tuning the bike with both the MasterTune TTS and his own custom setup. The following table shows maximum horsepower and torque numbers and gain over stock.
| Horsepower Gain over Stock | Torque Gain over Stock |
| HP | Gain | % Gain | Torque | Gain | % Gain |
| Stock | 66.8 | | | 83 | | |
| Yuill Base | 83.9 | 17.1 | 26% | 104 | 21 | 23% |
| Yuill with Vtune | 85.4 | 18.6 | 28% | 105 | 22 | 27% |
| Ed's Custom | 84.9 | 18.1 | 27% | 108 | 25 | 30% |
Next to demonstrate what a...
Next to demonstrate what a home tuner could achieve with the TTS Vtune program, Ed made two Vtune runs using the dyno. To do that, he followed the procedures in the TTS documentation for data collection then Vtune and new calibration. Ed Connected the TTS interface to the bike, then using the DataMaster program, he selected Record Vtune. Then we went for a ride at varying speeds and throttle positions. Afterwards we viewed the results as shown here. Each green cell represents a point where the program has adequate data for analysis.
As you can see, the Yuill Brothers base calibration file delivers some very respectable results right out of the box. That's a testament to how much effort they invested in tweaking the map to match their parts. The self-tune with the MasterTune Vtune program made only modest gains over the base; but by incorporating real data from actual bike runs, the difference is a smoother power curve and a better running engine. No matter how good the vendor's base calibration, until you can allow for bike-to-bike variables you can't optimize performance for a particular bike.
This is especially true for a custom dyno tune. Ed's final tune, using his setup, produced slightly less maximum horsepower and slightly more maximum torque. But the real story is that Ed produced gains in both horsepower and torque in the low to mid (2,500 to 4,500) rpm range and that on the whole he created a significantly smoother power curve. Both of these created a positive effect on the rideability of the bike.
Our conclusion is that the differences in these three states are small but tangible. A base calibration file from a vendor, like Yuill Brothers, that spends the time to tune it for their parts will let you run well. Then, to optimize the tune for an individual bike, you need some self tuning using whatever tools are available, preferably a high quality product like the MasterTune TTS. Finally, to fully tune all the variables for best efficiency and overall rideabiltiy, you need to let a qualified tuner, like Ed Dahir, tweak the bike on a dynamometer.
Dyno tuning is a small extra cost for a big gain in the quality of the ride.
 Next, we ran the Vtune program...  Next, we ran the Vtune program providing it with the base calibration file and the data collection file. The Vtune will generate a VE (volumetric efficiency) change map (shown here) for each cylinder. The Vtune can only make changes where it has data, so the VE table changes will roughly correspond to the green cells in the previous chart. Each run should produce fewer changes. Ed Pressed the Accept button to create a new calibration file and loaded that to the ECM. We were pleased with how the Vtune program improved on the original base file. |  Next, Ed created a custom...  Next, Ed created a custom EFI map for the bike. Starting with the Yuill Brothers base calibration file, Ed made a data collection run. He analyzed that data using his dyno software and custom spreadsheets. Based on his analysis, he used the TTS MasterTune program to edit AFR tables, ignition tables, and other variables. He blended the maps to cover both throttle acceleration and deceleration areas. This creates even performance and eliminates popping on decel. Ed repeated this procedure several times until he was satisfied with the results. |  Here is a dyno power chart...  Here is a dyno power chart showing the original Yuill Brothers base calibration (red) and Ed's final calibration (blue). As you can see the shape and maximum values are close. The telling differences in Ed's tune are the gains in the low to mid RPM ranges and the overall smoothness of the slopes. The Road King is like an all new bike. Powerful feel off the line and through the gears then instant throttle response while riding. |