KTM's Duke 690 has provided MCUSA with some great thrills in recent years. In the first part of our project bike we bolted on some performance parts to make it even better.
Love it or hate it, the last generation KTM Duke 690
was one of the most unique production motorcycles on the market. Part supermoto, part naked street bike and part something else, KTM
’s big-bore Single was hard to classify. One thing is for sure though - ask anyone who’s ever ridden one, and you’ll get one response: The Duke is just plain fun.
Although KTM has recently introduced the next evolution of the Duke with the 2012 model, we can’t really say we’re fans of the new direction and styling. But our fondness for the last generation 690 isn’t only skin deep. We were thoroughly impressed with the Duke’s performance back when we put it head to head with the Aprilia Dorsoduro 750 in our 2009 Aprilia Dorsoduro vs KTM 690 Duke Comparison
back in 2009.
However, the Duke still had some quirks. Since KTM has no current plans to import the new Duke to the US, it’s up to us tinkerers and third-party manufacturers to keep the progression going on this side of the pond. That's where our project 2009 KTM Duke 690 comes in. We wanted to take one of our favorite street bikes of recent years and see if we could make it near perfect. For the first part of our project, we will be heading straight for the motor to see if we can improve the 690’s overall ride-ability around town, on the highway and in the twisties.
The first upgrade we tackled was by far the easiest. K&N Engineering offers a High-Flow Air Filter
for the KTM Duke 690 that replaces the stock paper filter. Simply open the airbox, pop out the OEM filter and pop in the K&N. This five-minute
K&N Engineering offers high-performance replacement air and oil filters for the KTM Duke 690 - an easy upgrade.
upgrade couldn’t be easier and gives you better airflow than the stock filter which equates to slightly improved throttle response, power and fuel economy. Not to mention, the K&N filter is easily washable and re-useable so you’ll be spending less on replacements. K&N also offers oil filters
, filter cleaner
and filter oil
While the performance gain from a filter won’t knock your socks off, it will make a difference in the fuel economy, especially if you’re logging heavy mileage. For us, the practice of throwing away used filters always seemed wasteful, so we’ll be glad to wash and re-use the K&N for years to come. Now with more air flowing into our Duke’s motor, it was time to address the air flowing out.
Since the Duke 690 is somewhat of a niche model, there are only a handful of options for slip-on exhausts and even fewer choices for full systems. Since we were trying to milk every last pony out of this 650 Single, we decided to go with a complete system. To follow KTM’s mantra of sourcing the best parts for the Duke, we decided to tap Akrapovic for their Evolution Titanium Header
The Akrapovic Evolution Exhaust System is truly a work of art.
The Akrapovic system is completely constructed from Titanium alloy, so it’s ridiculously light: Just 6.4 pounds versus the stock exhaust weight of 15 pounds. But with an MSRP of about $2400 for the full system, you’ll be shaving some weight off your wallet, too. We’ll agree the price tag is a little crazy for a Single cylinder bike, but with Akrapovic, you know you're getting one of the best made exhausts money can buy. The full Duke system is no exception. The muffler is really a work of art. With smooth lines and aircraft-grade craftsmanship, the Evolution exhaust wouldn’t look out of place under the body panel of an F-22 Raptor. Over the last few months we’ve grown accustomed to the Duke drawing attention in the parking lot, but lately, more strangers have been commenting on the exhaust than the bike itself!
As with any new exhaust and intake, adjustments need to be made to the EFI settings to maximize the new set-up. For our application, the most basic option is to go with Akrapovic’s custom air/fuel and throttle maps that can be loaded to the stock ECU. This involves taking your bike to an authorized KTM dealer or service center to have them installed. Lucky for us, the guys at Motoworld El Cajon
were more than happy to help us with this step since they are an authorized KTM Dealer and Service Center. They’ve got a really great service facility and the process only took a few minutes to plug in the bike, download the map, and run the bike through the reset cycle.
After getting EFI settings maximized, Lee's Cycle completed more than 120 dyno runs to custom tune the new intake and exhaust.
The Akrapovic ECU map gave us a respectable performance gain, but it wasn’t what we were hoping for with such a large investment in the exhaust. No fault to Akro though, their map is meant as a one-size-fits-all solution, and to really get the most out of any new intake and exhaust set-up, you need to do some custom tuning.
Thankfully, the motor mad scientists at Lee’s Cycle
in San Diego were up to the challenge. In order to get the most out of the increased flow of the exhaust and intake, they did a full ECU tune. This includes a completely custom fuel/air map, throttle map, and engine timing for the Duke 690’s stock ECU. The Lee’s Cycle technicians completed over 120 runs on their in-house dyno to systematically dial in the optimal settings.
The benefit to a custom ECU tune such as this over a simple flash or plug-in adapter is the ability to tweak all the various maps within the bike's computer, not just the fuel and air mixture.
“We really got the most performance gain by adjusting the throttle and timing maps” explains Lee’s shop manager, Quentin Robles. “The stock throttle map has some limits on delivery that we were able to eliminate, and the timing adjustments helped us maximize the overall power output.”
The best part though is Duke owners out there can take advantage of all our R&D time on this project bike. If you’ve got a Duke with an aftermarket exhaust or intake, the guys at Lee’s Cycle can give it a full ECU tune just like we did for this test, for $450. Just bring in your bike with your aftermarket parts either installed or separate, and they will give it a full tune to make the most of your set up. They are also able to disable the O2 sensor and secondary air intake warning lights if you are going for a full-racing set-up.
With all our performance parts installed, it was time to test the Duke out on the road.
On the Dyno, our modifications gave us a 2-plus horsepower boost, or about a 4% increase. While that may not sound like a lot, when you couple that with the 3% weight savings, the result is a noticeable seat-of-the-pants power increase out on the road.
The Duke's new intake and exhaust netted a 4% increase in horespower and provided a major boost to its mid-range pull.
The Duke now has some serious mid-range pull. While the big Single was never really hurting for bottom-end, it now has that arm-yanking and grin inducing mid-range acceleration that's mostly found on multi-cylinder machines. The main problem now is trying not to rip away from every stop light like I’m trying to holeshot the Toyota Sienna next to me.
The top end is much improved as well. The Duke will now comfortably cruise at 80 mph, where before the 650 Single didn’t want to maintain anything higher than mid-70s for sustained highway rides.
We aren’t quite sure what physics are involved here, but after installing the Akro system, we’ll swear that the engine vibration is also reduced at high speed as well. The cockpit doesn’t feel quite as buzzy at freeway speeds, and is actually quite tolerable now. Our guess is the reduced weight of the exhaust results in less mass being thrown around by the engine’s vibrations, thus less inertia for the vibrations to be carried to the rider. This, of course, is all based on our B.S. degree in Motorcycle Physics. Either way, the Duke is now much more tolerable on the highway, making it an even more well-rounded machine.
The Akrapovic system sounds amazing, too. It has just the right amount of deep raspy tone, it’s not overly loud or snappy like some Single cylinder exhausts can be. The note lands somewhere between that of a factory motocross bike and a Ducati Twin. It is a vast improvement over the stuffed up sewing machine sound of the stock exhaust.
Was the Akrapovic Evolution System worth the price? If straight horsepower numbers are your thing, maybe not. There are other systems out there that could give you a similar gain in HP for a lower cost of entry. But all things considered: fit, finish, weight, power and sound, you won’t find a higher quality exhaust on the market for the Duke 690 than the
With just a few small additions the Duke has already been made more versatile.
Akropovic Evolution. And who knows, maybe with the 2008-2011 Duke lineage coming to an end, you might be able to snatch one up on clearance in the near future.
Overall, the improvements we made to the Duke's motor department make it a much more versatile bike. The extra power gives it that little bit of extra zip it needed for the highway and the mid-range boost is just plain fun no matter where you ride.
Make sure to check back for Part 2 of our KTM Duke 690 Project, where we will fit the Duke with a custom seat, tires and some other bolt-ons in our mission to make it the ultimate hooligan commuting machine.