Live With This: 2019 KTM 790 Duke Long-Term Review

I’ll just begin with this: I haven’t had this much fun with a motorcycle in years. Seriously. When I’m around the 790 Duke, I’m as giddy as I was when I first started riding. Even my wife, who usually rolls her eyes when I start talking about motorcycles, has told me that she hasn’t seen me this excited about a bike in as long as she can remember. The other staff MOrons also tease me about the 790. If I weren’t so dang happy, I’d be embarrassed. 

MO has had the KTM 790 Duke in its collective possession for almost seven months, and we’ve gotten to know it pretty well. So, we knew the time was ripe for a follow up to my First Ride Review. However, I was concerned that writing the update would remind the folks at KTM that we still had their bike and prompt them to ask for it back, which would make me very unhappy. So, I came up with a plan, and it seems to be working.

2019 KTM 790 Duke Review – First Ride

The 790 would become a project bike, making it necessary to keep the Duke in our stable for as long as possible. We’ll start with our modifications the way many new bike owners do, by installing factory accessory parts before branching out into the aftermarket in future installments. That’s the plan, and we’re sticking to it – at least until KTM demands their bike back. 

Day-to-day life

The 790 Duke has acquainted itself quite well to the varieties of chores it’s been given. In commuter mode, it has proven to be a worthy weapon for scything its way through the worst traffic that Los Angeles has to offer. On interstate highways, it is a handful – but not in the way I thought it might be. The engine’s smoothness frequently puts me in the position of accidentally going way too fast. Get-pretty-silver-bracelets-fast. Frequently, I look down at the TFT screen to discover that I’m going between 90 and 95 mph. It boggles my mind that I’m on a naked bike with no form of wind protection, and yet, I’m not aware that I’m hauling ass. It’s crazy. 

2019 KTM 790 Duke

A great starting point with only a couple items that really screamed out to be changed. (Photo by Simon Cudby.)

The engine is a huge part of what I love about the Duke. Yes, I am extremely partial to parallel-twins because of their narrowness and my personal history with them. However, the physical configuration is only part of the magic. The 75-degree offset of the crankpins combine with a 435-degree firing order to approximate the feeling of KTM’s bigger 75-degree V-Twins. Add to that V-Twin character the most seductive power delivery I can remember, and you’ve got a good time on your hands. Yes, a 1290 Super Duke R can eat the 790 for lunch, but its engine is so powerful that you really can’t pull its tail for anything more than a few seconds on the street. With the 790, you can enjoy more extended runs into the top of the power band, snicking your way through the gears. And the smoothness enabled by the dual counterbalancers can’t be understated. Those Austrian engine designers know what they’re doing. 

Rereading the above paragraph, I feel I need to clarify about engine vibration. Any parallel-Twin will vibrate in the upper rpm range, and the 790 is no different. Wring its neck, banging shifts right around redline, and you’ll notice that the grips and pegs do vibrate. Just not as much as with other parallel-Twins. Drop the tachometer down to the mid-range, and the Duke gets unbelievably smooth. That’s what’s gonna get me in trouble if I’m not careful. 

2019 KTM 790 Duke action shot

Whether you’re riding around town, hauling down the highway, scratching in the canyons, or strafing apexes at the track, the KTM 790 Duke is versatile enough to make any activity an event.

So, what about the quirk I mentioned in my initial review? The failed upshifts I encountered on my introductory ride have not been an issue. First, I have to say that those problems were encountered on a different loaner bike. When our first 790 developed a strange top end knock, KTM asked us to swap bikes before our comparison with the Triumph Street Triple R (and we obliged them), and this Duke hasn’t suffered from either the shifting or rattling issue. However, I have spent enough time haunting 790 forums and Facebook groups to know that my missed shifts with the first 790 weren’t a completely isolated experience. While the symptoms for me were missed shifts (the quickshifter cut the power, but the transmission stayed in the same gear), more people appear to have an issue with false neutrals. I don’t think this is super common, but it is out there. Still, I think I can count on one hand the number of times I’ve missed a shift on this particular 790. 

A Disruption In The Force: KTM 790 Duke Vs. Triumph Street Triple R

When it comes to the auto-blip downshifts, I have to say that the 790 has grown on me. I don’t know if I’m doing something different, but I’m much happier with the quickshifter now. I use it constantly – both around town in traffic and when railing through the canyons. The shift from first to second requires some technique, but once mastered, the shifts are butter-smooth. The trick in traffic is to short-shift, and you can change gears at neutral throttle. Otherwise, you need to be accelerating smartly. The downshifts simply work. 

Niggling complaints

One problem that cropped up at about 1,300 miles is that the countershaft seal started to leak. At first, it just looked like excess chain lube seeping under the countershaft sprocket cover, but as the leak progressed, it became clear that the problem was an oil seal. The fix is pretty simple for a mechanic of average skills. Still, we’re waiting to have it done the next time we take the bike to be serviced. We just keep the engine clean and check the oil level frequently. 

2019 KTM 790 Duke oil leak

Once I removed the countershaft cover, it was plain to see that the oil coating the engine came from the countershaft seal and not excess chain lube.

An electronic oddity that we have noticed is that every time the ignition is turned on – even when the tank is low on gas – it reads as two bars from full. After a few miles, the fuel level reads normally. This has caught me out a couple of times, but I’ve found that range readout is always accurate. So, I always check it when I first get on the bike. 

2019 KTM 790 Duke coolant leak

Back home after a day on the track at Buttonwillow, this sight greeted me when I began unloading the bike from my truck. Yes, it’s coolant.

Another glitch I encountered with the 790 came just this week after a trip to Buttonwillow with Cali Track Days. The cooling system leaked on the way home. Although I haven’t confirmed the issue, I suspect one of the hose connections to the radiator is the culprit. This will be addressed in our next service at KTM.

The 790’s speedometer reads on the high side. I checked it against the GPS on my phone and found it to be 4-5 mph over the actual speed at 80 mph. That’s ok. I can do simple math and ride at the same time when I see a black and white in the vicinity. 

A few non-sequiturs: The speedometer jumps into night mode very easily sometimes from something as simple as riding through the shadow from a tree. However, it doesn’t switch back to day mode as quickly. I’m guessing that this is a safety feature for night riding where the day mode could throw glare into the rider’s eyes, say if you rode under a street light. When night riding, I really like the backlit buttons on the switchgear. The turn signal switch is in an awkward position, causing me to occasionally have a hard time signaling a left turn. The coolant expansion tank’s level check window is just about useless. We’ve averaged 39.3 mpg over the length of our possession of the Duke. (This excludes track days because we pour gas directly from a can into the bike.)

2019 KTM 790 Duke beauty shot

Stage 1 of our KTM 790 Duke project in track trim (shorn of mirrors and brake light/rear turn signals).

On to the modifications!

Many riders buy their first mods for their motorcycle at the time of the bike purchase so that they can tack the parts onto the bike loan. Consequently, their first changes are usually found in the manufacturer’s accessory catalog. I spent a lot of time on the KTM website, shopping out the PowerParts that I thought would most suit the bike and ended up with what I consider to be a fairly typical selection of KTM’s accessories. 

Beautification

In my opinion, the biggest stylistic warts on the 790 Duke are the passenger pegs and the hangers that hold them in place. So, I ordered up the Silencer Bracket ($78) to hold the pipe in place without the right side passenger peg. While I was planning to toss the pegs (and save 3.8 lbs., by the way), I figured the pillion should go, too. Next came the Pillion Seat Cover ($125), which completely replaces the passenger seat. 

2019 KTM 790 Duke stock exhaust

If you’re on a budget, the Silencer Bracket and the Pillion Seat Cover are a nice way to make the 790 Duke look sportier and shave off a total of 5.6 lb.

Installing the silencer bracket took maybe 15 minutes. On the left side, the peg-mount was removed and shorter bolts torqued in place to the specifications included in the kit instructions. On the right, the muffler had to be mostly removed before the peg bracket could escape. In short, a total of five bolts had to be removed and replaced. Easy-peasy. 

The pillion cover took a good bit longer because it didn’t come with the bolts to secure the rear pad to the cover. I’d expect better from an OEM part. So, 20 minutes and $2 later, the pad was secured with a pair of stainless steel bolts and washers. (Oh, how I love my local hardware store.) I also had to mount the orange stickers on the sides. No biggie. The Pillion Seat Cover cuts another 1.8 lb.

The KTM PowerParts Fly Screen ($89) arrived from backorder just before I posted this article. I selected it because it completes the swoopy lines of the headlight and covers the blocky shape of the instrument cluster. I didn’t expect it to have much of an influence on the wind blast, but I was pleasantly surprised at how it smoothed the air hitting my chest.

While the ease of installation and the quality of the Silencer Bracket was exactly what I’d expect, the Pillion Seat Cover seems cheaply made. Yes, its style perfectly matches the rest of the bike when viewed from a distance. A close inspection, however, reveals some inconsistencies in the surface from the injection molding process. Still, it earns a B while the exhaust bracket is a solid A. The back of the Duke is transformed with the addition of just these two parts. Also, if you’re not interested in replacing the muffler, the shapely stock muffler looks much better when it is no longer obstructed by the passenger peg. 

Improved sound plus weight savings

The next item to get installed was the Akropovič “Slip-On Line” ($860) from the KTM PowerParts catalog. Even if the passenger peg were still on the bike, this modification is just a two bolt operation. Remove one bolt on the muffler and the one on the strap that connects the expansion chamber/catalytic converter to the muffler then wiggle the stocker free. The Akropovič goes back on just as easily. After you torque the bolts down, wipe the entire slip-on with a clean cloth so that you don’t burn your finger marks into the pretty titanium of the canister when you fire the engine up. 

2019 KTM 790 Duke PowerPart Akropovic slip-on

The Akropovič looks and sounds so sexy on the 790. Too bad it didn’t add any power. Perhaps, that’s the price you pay for all the baffling required for 50-state legality.

What a sweet sound this 50 state, EPA-legal slip-on puts out. No, it’s not much louder than stock, but the note is deep, resonant, and quite pleasing to my ear. I’m not a huge fan of loud pipes on the street, and I think the Akropovič does a great job of balancing the exhaust note we crave with consideration of those around us. 

2019 KTM 790 Duke dyno chart

The Akropovič slip-on’s power curve almost exactly mimics the OEM curve, only slightly worse.

Aside from saving 2.1 pounds, the Akropovič slip-on has a slightly negative effect on the horsepower. In side-by-side dyno runs, the peak power dropped 0.8 hp, and the effect in the midrange was similar. Although a disappointment, this should really come as no surprise since OEM exhaust systems have gotten so good in recent years. The other thing to note is that KTM PowerParts makes no claim for increased horsepower. Rather, they are counting on our assumption that it will make more. Finally, I defy the typical rider to tell the difference that a single horsepower makes in a bike’s rideability.

Yes, there is power to be unlocked by extracting the dB killer baffle in the slip-on (there are YouTube videos demonstrating how), but as I said before, I don’t believe in overly loud pipes on the street. Personally, the sound is so pleasurable that I don’t begrudge the minimal power loss – too much. (Don’t worry, I’m already working on finding more streetable power from future updates.) Let’s not forget that the weight savings is 29% versus stock, which helps to offset the power loss a little. 

Finally, some people have told me they think the muffler is too big, but I think it looks pretty sweet. Beauty is, as they say, in the eye of the beholder. If you want a smaller EPA-legal slip-on, Yoshimura has one.

New shoes

2019 KTM 790 Duke Michelin Power RS tires

Michelin’s Power RS tires were the third set of buns we’ve put on the 790 Duke.

Although we had no problems with the stock Maxxis tires on the street, we opted for Dunlop Q4s for our track day during the shootout with the Triumph Street Triple R and rode with them on the street until we were well into the wear bars. Troy’s impression of the Q4 rubber on the track is that they get up to temperature quickly and don’t require tire warmers. Unfortunately, he feels they sign off early when it comes to rear grip. However, this gave him the opportunity to feel how well the 790 manages its traction control. Where on some bikes the TC can be felt actively cutting power, the 790’s TC can be felt trying to feed out as much power as possible without slipping – an important distinction. On the street, the Q4s worked like the top-shelf sport tires that they are. However, we failed you because we neglected to write down the mileage when we changed to the Dunlops. So, we can’t say how long they lasted. In our defense, we never really planned on keeping the 790 this long. It just sort of happened. 

The Duke’s current tires are the Michelin Power RS, a street tire that we’d only sampled on the track and that we’d been itching to try out on the street. We’ll give an update on them after we’ve logged more miles, but our impression is that they are every bit as fun on the street as they are on the track. As with my first impression of the tires, they do slow the steering a little compared to the Q4s but not in a problematic way. So far, they’ve got a few hundred street miles plus one track day, and they appear ready to go significantly longer. 

More stopping power

2019 KTM 790 Duke EBC brake pads

These EBC HH pads address the complaint about a lack of initial bite on the 790 Duke.

One common complaint about the 790 Duke has focused on the lack of initial bite from the front brakes. While I have not personally been overly bothered by this, I thought I’d see if swapping out the stock brake pads for some EBC Double-H pads made a difference. In the past, I’ve had good luck with them. So, I thought I’d see if they worked their magic with the KTM calipers and rotors. 

After bedding the EBC pads in, I found that the initial brake application delivered much more bite, with their stopping power building linearly from there and giving a very precise feel at the lever. At the track, the EBC pads hauled the 790 down from speed with much less lever effort and greater feel – regardless of whether the bike was straight up and down or trail braking to the apex. Overall, I think that $40 for each pair of front pads is money well spent if you’re among the people who felt shortchanged by the stock KTM/J.Juan pads. Although I installed the $37 rear pads, too, I didn’t notice much of a difference in braking power, which is probably due to the way I use the rear brake. I never felt anything lacking from the OEM rear pads.

Protection

2019 KTM 790 Duke PowerPart case guard

One way to tell that this is a KTM PowerPart is that the case guard doesn’t cover the KTM logo.

One area that I usually focus on when modifying a motorcycle is crash protection. If I am unfortunate enough to have a mishap, I hope to be able to ride the bike home. My first steps towards this goal are the KTM case protectors. The Clutch Cover Protection ($75) and the Ignition Cover Protection ($75) are simple bolt-on parts that should help keep the oil inside your cases in a slide. The orange of the CNC-machined aluminum protectors looks great. Installation only took 10 minutes. Simply replace the 5 bolts that hold this armor in place (along with releasing and re-torquing the other cover bolts). Still, I’m puzzled as to why the vulnerable water pump cover did not receive a factory protective option, too. I’ll keep looking for the appropriate piece in the aftermarket. 

2019 KTM 790 Duke Evotech radiator cover

The Evotech-Performance Radiator Guard looks and fits like it is an OEM part.

Finally, after being pelted with road debris that the sticky Dunlop Q4s were tossing at me as I followed Ryan on a Sunday morning canyon descent, I decided the Duke’s radiator looked awfully naked. So, I ordered up an Evotech-Performance Radiator Guard ($130). This black powder coated, machined aluminum cover looks like it should have been part of the Duke’s factory design. The front grill has a mesh that is fine enough to prevent damage from stones while still allowing ample cooling airflow. The guard is held in place by two side covers that wrap around the ends of the radiator and dress up what was a rather mundane part of the engine. The Evotech’s fit and finish make it look like original equipment and not an add-on part. 

Riding position

2019 KTM 790 Duke handlebar clamp

Moving the handlebar clamps to the forward hole on the triple clamp and rotating the bar forward opened the riding position up just enough to improve highway comfort and allow for a tuck on the track.

The 790 Duke’s handlebar offers a good bit of adjustment. First, I removed the bar itself to shift the clamp to the more forward of the two mounting holes in the triple clamp. Next, I rotated the bar to the limits of the adjustment markings. This gives my upper body a little more forward lean into the wind on the highway without compromising the comfortable, mostly upright torso position that I like so much about the bike. Additionally, during track days, the new location of the grips provide a more aggressive body angle for attacking the corners – though I still need to slide my butt all the way back to the pillion cover’s pad to get my upper body out of the wind blast on the straights. 

That’s it for Phase One of our KTM 790 Duke project. I’ve already got other plans for the bike, but for now, it needs to stay as functionally close to stock as possible. Why? Well, we’ve got another shootout scheduled for it in mid-July. 

2019 KTM 790 Duke track action shot

I’m already planning my next track day with the 790 Duke. (Photo by CaliPhotography.)


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