Big Dog Pipe Upgrade
The Big Radius pipes feature 2-1/2-inch full-coverage heat shields, scalloped end tips, a mounting bracket, new intake-manifold gaskets, exhaust gaskets, and flanges and caps. After the stock two-into-one pipe was cooled down, Randy removed the old pipes.
Next, a small amount of threadlocker was applied to the bracket mounting bolts. Then he bolted the new mounting bracket onto the frame.
Then he removed the old exhaust gaskets and installed new, thicker gaskets.
In the bag of hardware there was a new set of exhaust flanges and retainer clips. The head flange was installed first, followed by the retainer clip.
Next, the bolt insert was placed in the exhaust-pipe mounting bracket. Randy loosely bolted the pipe to the head until he got the rear of the pipe bolted to the bracket.
After everything was lined up, he tightened up the head bolts.
The heat shield was installed next. The clamps were placed in the keepers, and then the shield was placed over the pipe. Finally, the claps were tightened.
After all the same steps were performed on the rear pipe, the pipes were cleaned of any oil and fingerprints to prevent scarring on the pipe from the heat. Randy then got started on swapping out the jet kit.
The cover, air filter, and backing plate were removed. The float bowl was removed from the carb.
Next, the jets were replaced. The old main jet was a 68 and is now a 76, and the intermediate was a 28 and is now a 31. More airflow from and to the motor means it needs more fuel and bigger jets.
After the jets were in place, a new float-bowl gasket was also installed. Then the backing plate, air filter, and cover were re-installed so we could get one more dyno run.
Once the bike was up to operating temp, Sparky made a dyno run. Straight out of the box, the bike made 105.81 hp and 116.44 lb-ft of torque.
You and your motorcycle. What can you do about the missing sound and power from the bike? You know-from all you were told when you bought the bike, there should be a lot of power still hidden in that big-inch motor somewhere, but where? If you’re like most riders, style, performance, and sound are what you’re looking for when it comes to your bike.
So what happened to all that power? A quick two-word explanation would be “governmental regulations.” The motorcycle industry has to conform to many seemingly never-ending new regulations. In theory, these regulations should be a good thing for long-term health issues, but they make our bikes run far below their rated capacity.
This became apparent when we dyno’d an ’06 Big Dog Mastiff and only recorded 97 horsepower-from a 117-inch motor. We called the factory to find out what options were available, and we were directed to the Big Radius exhaust system. While the pipes alone would not solve all of our missing power and sound issues, they would give us a deep, throaty sound and add to the stock horsepower numbers.
The Big Radius two-into-two performance pipes have style written all over them. The system includes the pipes with heat shields and all the necessary mounting hardware. The MSRP for this set is $649 (recommended jet kit sold separately.) This is not a street-legal kit, since after we install the new pipes the bike will not meet the EPA’s noise regulations and noise emissions standards, but we still like the look of the pipe.
We stopped at Lifestyle Cycles (a Big Dog dealer) in Anaheim, CA, to install and get a few dyno runs in. Before we knew it, Sparky and Randy had the bike up on the dyno, and it was ready to go. They ran the bike on the dyno with the stock pipe to get some base numbers, which turned out to be 107 lb-ft of torque and 97 hp.
