Sturgis Rally
Sturgis Rally
Font size: +


Originally posted by Buck Lovell on Sunday, 20 May 2012 in Buck Lovell's - American Biker Blog


Like everybody says, the Harley-Davidson Big twin motor is essentially an air pump. The more fuel-air mix you can pack into those two cylinders at a single gulp, the more horsepower you'll get at the rear wheel…..The stock exhaust and air cleaner are the biggest impediments to free breathing with the Harley-Davidson V-Motor. California residents check your local regulations regarding exhaust and air cleaner. Sooner or later California bureaucrats will kill off the motorcycle industry in that state, and the associated tax revenues. Sorry…I got distracted. Replacing the restrictive EOM breathing apparatus of the Big Twin will not only increase horsepower but improve fuel economy, and reduce emissions at the same time. Regardless of what brand of aftermarket air cleaner, or what brand of exhaust product is used, the Harley-Davidson motor will run better, cleaner, and cooler with an intake and exhaust upgrade.

I opted to install Cycle Shack "SLIP-ON" mufflers, and a Ness Big Shot air cleaner on my brand new 2010 Harley-Davidson Dyna Glide. I located the bike a a Midwest dealership in mid 2011. Prior to installing these two products the motorcycle was tested by Randy Cramer on the house dynamometer at Dakota V-Twin in Spearfish, South Dakota. Dakota V-twin is the popular local and reliable motorcycle tune-up shop. This was done to determine genuine horsepower output, rather than rely on the factory brochure specification. The reading was a paltry 59 horsepower, this was with a thoroughly broken in motor (3000 plus miles on the clock). The dyno run also revealed that the motor was running on the rich side of stoic above 4000 RPM.

Cycle Shack mufflers and the Ness Big Shot air cleaner kit were installed as the motorcycle sat on the dyno (after a cool down period of course). Both are available from the Drag Specialties Fatbook. No tuner was installed at this time, I just wanted to get a dyno reading of the improvement resulting form a simple swap of the breathing equipment. Now the motor is running ever so slightly on the lean side below 3000 RPM, and damn near perfect above 4000 RPM. After the installation of the two product, horsepower went to 71. That's an 18- 19% increase in horsepower with just the swap of the air cleaner on the intake side and the mufflers on the exhaust side! And I got louder pipes to boot, which adds a huge safety factor. Even if they can't see me, they might hear me! One can only surmise that fuel economy will be improved as well.. At any rate it was well worth the time and small amount of cash to replace those two items in terms of horsepower, not to mention the motorcycle now sounds like a Harley-Davidson should…..loud pipes save lives, always!

To be installed on my 2010 Dyna Super Glide mule are Cycle Shack “slip-on” mufflers available from Drag Specialties, and a Ness “Big Sucker” air cleaner, also available from the Fatbook. See your local Drag Specialties dealer.
My stone stock Dyna Glide with 3500 miles on the odometer needs a little help in the breathing department. Only 59 horses showed up on the Dyno run.
The stock air cleaner/airbox was removed and replaced with the Ness inner air cleaner mounting plate.
The Ness Big Sucker air filter element is next, three bolts attach it to the mounting plate.
The stock air cleaner cover bolts on to the Ness Big Sucker hi flow air cleaner assembly.
Loosen the clamps holding the stock slip-on mufflers in place. Remove the stock mufflers.
Install the OEM muffler clamps on the Cycle Shack traditional style, slip-on mufflers.
The stock muffler bracket is used with the Cycle Shack mufflers.
Double check and tighten all the muffler clamps and other hardware and very important….wipe the mufflers clean before starting the motor.
Randy Cramer is running the Dyno. After the simple installation of the Ness Big Sucker AC, and Cycle Shack mufflers, the motor now produces 71 horsepower.
For traditional looks, dual slip-on mufflers can't be beat. The hidden cross over (balance) pipe helps the motor run better than a dual exhaust system would without a balance pipe. See your local Drag Specialties dealer.
WALL OF DEATH AT THE CHIP 2012..........
FOR $50 DOLLARS I WILL SHOOT YOU!!................
Get the News Before Official Public Announcements!