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Tech & How-to



The owner of this 2009 CVO 110″ wanted the same things as thousands of other Twin Cam owners, be they 88s, 96s, 103s, or 110s: a better exhaust note, smoother idle, no popping on deceleration, better off-the-line power, and, you guessed it, more power across the board, not only at a high rpm. That’s a reasonable request to be sure, but not one that many shops can deliver at a reasonable price. That’s why I called my buddy Andrew Rosa in nearby Huntington, New York. His Long Island shop, Rosa’s Cycle, has been cranking out smooth, dependable power from Harleys, be they Twin Cams, Evos, or Shovelheads, for almost 30 years.

Andrew’s plan is simple, and yet involved. The simple part is to get more air in and out of the engine, which is why he likes to bolt on a SE Stage II air cleaner, Rinehart exhaust, and a H-D Screamin’ Eagle Race Tuner (SERT). The involved part comes after this package is installed: that’s when Andrew’s years of dyno experience come into play. Others with less experience will spend many hours trying to get the idle smoothed out, the bad dip in power off idle corrected, and a respectable power increase out of these basic upgrades. Andrew, however, gets it all out the door and running sweet for a reasonable number.

For this upgrade we decided to use the newest addition to the H-D lineup, a 2009 Road Glide from nearby (to Rosa) Lighthouse Harley-Davidson. We went with a CVO 110″ because these engines seem to have a chronic idle problem and a bad dip in power at lower rpm. In their favor, they come equipped with a SE Stage II air cleaner and a high-flowing dual header system from the factory. That means all Andrew had to do was bolt up a set of sweet-sounding Rinehart slip-on mufflers (available from Drag Specialties), connect a H-D Super Tuner SERT, and work a bit of his magic in the dyno room. The accompanying dyno chart tells the tale.

–Chris Maida as published in American Iron Magazine, the world’s best selling Harley magazine.

• 9/16″ socket
• 1/2″ socket

Drag Specialties
See your local Drag dealer

Lighthouse Harley-Davidson
670 E. Jericho Turnpike
Dept. AIM
Huntington Station, NY 11746

Rinehart Racing

Rosa’s Cycle Shop
540 New York Ave.
Huntington, NY 11743

1 Our opening shot shows the saddlebags removed from our stone stock CVO 110 Road Glide, which is on Andrew’s dyno, all warmed up and ready for some power runs.

2 Andrew uses a 9/16" deep socket to loosen the clamp that holds the stock muffler to the rear cylinder header pipe. Save the clamp and all the stock hardware. Do the same on the other muffler.

3 A 1/2" socket is needed to release the rear of the muffler from the stock support, which is part of the saddlebag bracket. Again, save all the stock hardware and do this to the other muffler.

4 After he puts the stock muffler clamp onto the front of the new Rinehart muffler, Andrew slips it into position on the rear cylinder header pipe and loosely secures it with the stock hardware.

5 The clamp gets tightened to H-D spec first, followed by the rear hardware. If you have a gap between muffler and bracket, don’t pull it closed with the bolts. Shim the gap closed with washers. By the way, ours lined up perfectly.

6 After he installs the front muffler in the same way, Andrew plugs in the H-D Super Tuner SERT to the stock data link plug on the bike.

7 Then it’s time to fire up the dyno and dial in the engine. This is where experience comes in. If you don’t know what you’re doing here, the cost of the installation goes through the ceiling.

8 Swapping out both mufflers takes all of about an hour, including reinstalling the bags and side cover, and wiping down the bike. Here’s how the Rineharts look from the back. Nice! AIM