In the V-twin world of “I’ve got to have the latest and greatest,” one thing we see changed on motorcycles more than underwear is exhaust systems. Most guys start out looking to change the sound or looks of the bike first and tend to overlook power gains. After riding for a while though, they start to think it’s not so much the sound they are after, as it is more power. They may hear about the newest exhaust system and how great it is with all its power, only to find that if the bike is not tuned right, all that power he heard about may never be found.
This is where a complete package can help. If you’re going to add pipes, don’t forget the air box and tuner (if fuel injected) to get the most out of your bike. But what if you don’t have a dyno close to help you tune and map the bike after everything’s added?
01. Here are the Tri-Oval mufflers, Power Port head pipes, and heat shields.
We talked with COBRA Engineering about its new PowrPro Fi2000 with Continuously Variable Tuning (CVT), which eliminates the need for dyno tuning and remapping after any modifications have been done. From swapping out the air box to engine hopups, the PowrPro Fi2000 analyzes info from the bike as you ride at a rate of 80 times a second and tunes the bike as needed for optimal performance.
We asked Camron Bussard, head of marketing, just how it works.
02. We removed the stock exhaust system and air cleaner. Jon, the service tech, had all t
“You already own a highly accurate dyno, your engine’s crankshaft. We think of crankshafts as turning smoothly, but in fact when a cylinder fires, it accelerates the crankshaft slightly. Every engine has some kind of torsional shock absorber between crank and gearbox, which is there to accommodate this slight variation in crank speed. With the application of modern high-speed electronics, we can access this information and time the rotation of the crank from one firing to the next, and analyze whether the next firing is slightly stronger or weaker than the previous one. The clever part is using the measurement of how hard a cylinder accelerates the crankshaft as a way to correct fuel mixture. If the mixture is a bit lean and our system adjusts it to be a bit richer at the next firing, more power will be produced and the piston will give the crank a slightly stronger kick. We can use this as a tool to move from whatever fuel mixture the engine is actually receiving towards a more efficient mixture. The next step is a way to time the rotations of the crank, so crank speed at one firing can be compared with crank speed at the next firing. Fortunately, bike manufacturers give us this info for free, as the time from the beginning of one fuel-injection squirt to the beginning of the next one, 720 crank degrees later. Yes, the engine’s other cylinder may be slowing the crank by being on its compression stroke, but all we need is comparative information. We also need to experiment with fuel mixture, just as race tuners or EFI programmers do. If we make the mixture a little leaner and the next crank cycle takes a little bit longer than before, we know we’re going the wrong way. This is just like what old-time race tuners did by changing carburetor jets and then looking at the bike’s quarter-mile ET or lap time.”
“The Fi2000 PowrPro conducts its fuel-mixture tuning by varying the mixture slightly. If the crank moves a tiny bit faster when the mixture leans out slightly, the PowrPro knows that’s the right direction and the system leans the mixture again, or vice versa. With a big twin cylinder engine turning 5,000 rpm, one cylinder is giving us 42 of these opportunities to tune fuel mixture every second. The result is that the Fi2000 PowrPro continuously and quickly drives fuel mixture to the value that gives best power. This process allows the system to adapt to any engine modifications you make.”
We contacted COBRA and as a complete package ordered COBRA’s Power Port dual head pipes ($479.95), Tri-Oval mufflers ($539.95) and PowrFlo air intake system ($249.95), along with the Fi2000 PowrPro tuner ($599.95). We have a stock ’10 Road Glide Custom in need of more power and better sound, and Jose (the owner) was tired of looking at the stock pipes. We took the bike over to the COBRA plant to do the install and see how well the bike can run. To get started, the bike was run on the shop’s dyno to get some base numbers. In stock form with 2-into-1 pipe, the Road Glide squeezed out 68.1 hp and 77.3 lb-ft of torque, just about what we figured to get from a stock setup. Afterwards, the bike was placed onto the lift and the COBRA team went to work. B
03. The stock H-D flanges were removed from the headpipes, then re-installed on the new C
04. The O2 sensors were removed from the stock headers and installed into the bungs on th
05. Jon installed the mounting bracket for the front header pipe onto the lower transmiss
06. The front pipe was then installed to the head, and the O2 sensor wires were routed ne
07. The same went for the rear head pipe. Jon bolted the pipes in place but did not tight
08. Next, Jon removed the stock H-D bracket for the rear pipe and replaced it with the CO