KTM 790 Duke Project: Building A 790 R

by | Apr 23, 2020 | KTM, motoGP News, Triumph

When I initiated this project with MO’s long-term 790 Duke, my goal was simple. I just wanted an excuse to keep the bike as long as possible before I would be required to give it back to KTM. However, even before I considered buying the 790 for myself, I hatched another plan. I was going to build my vision of what a 790 Duke R would look like. Now, KTM has let the cat out of the bag and proved that a 790 Duke R really was never planned, meaning that it decided on an 890 Duke R instead. While it is beyond my capabilities to bump up the engine’s displacement (and retune the counterbalancers or shorten the shifter throw, among other things), as I run down the list of changes I applied to my 790, I don’t think that, although I was just trying to craft my conception of the ideal naked middleweight Twin, I strayed very far from where KTM has taken the 890.

Building an R

The two places where KTM cut corners on the 790 Duke are pretty much agreed upon: the brakes and suspension. Fortunately, there were several good options available to address these issues. Rather than saying these were shortcomings in the Duke, I felt these were obvious clues as to where the next iteration of the 790 was heading. After all, Triumph has been quite successful with multiple variations of its Street Triples. Why wouldn’t KTM do something similar? At least, I was half right.

KTM 790 Duke R Project

In the comments of the other articles I’ve written about this project, some of the more cynical readers have approached these changes as things that I needed to fix – as if there was something inherently wrong with the Duke. I see it more as I was excited by the platform’s potential. That’s why I ended up buying the 790. The desire to sharpen the bike’s performance simply makes sense for a rider of my background, and the fun of taking on this sort of project can’t be ignored. I’ve spent many happy weekends in my garage wrenching on the 790, but the real payoff is riding the bike that I’ve created.

Adjustable Suspension

The non-adjustable OEM suspension was the 790’s Achilles’ heel. Although it offered the compliance that makes street riding more comfortable, it could find itself out of sorts at track speeds. When I made my list of upgrades for the 790, finding new suspenders for it resided at the top of the list. Unfortunately, I had to wait quite a while before I could make the change because of articles we had planned for our long-term Duke.

KTM 790 Duke R Project

The preload-adjustable only stock shock was swapped for a reservoir shock that has hydraulic preload adjustment, high/low-speed compression damping, and rebound damping.

Although I shopped around, I pretty much knew that I’d end up with the WP Apex Pro components. First, KTM owns WP. So, they belong together. Then there was Chris Fillmore’s record-setting run up Pikes Peak. WP’s reputation for quality components and the fact that I’d never ridden on non-OEM versions of WP suspension before and wanted to see how it performed played an important role in my decision. Also, WP markets the Apex Pro as street-focused, and that fits for most of what I do with the bike. The full-adjustability of the suspension allows me to tune the ride for the task at hand. I have three settings that I typically use: sporty, for every day rides and canyon runs; soft, for extended freeway time; and track, which varies for each venue. I couldn’t be happier with the WP suspension.

KTM 790 Duke R Project

Yes, the WP Apex Pro fork is fully adjustable for preload, compression, and rebound damping. With the stock fork, you get nothing.

The cost of the WP Apex Pro components ($879 for the Apex Pro 6500 cartridges and $1099 for the Apex Pro 6746 shock with the optional hydraulic preload adjuster) is nothing to sneeze at, and this upgrade alone put the cost of my project over the base price of the 890 Duke R – $11,699. However, according to our contacts at KTM, the 890’s suspension slots in between the 790’s and the Apex Pro. For example, the 890’s fork has no preload adjustment, and the shock, while offering full adjustability, is of a different construction.

MO Tested: WP Apex Pro 6500 Cartridges And 6746 Shock For KTM 790 Duke

Better Brakes

Brake upgrades were among the first changes I made to the bike, and I’m happy with the progression throughout the course of this project. The baby step of fitting EBC Double-H pads delivered the desired initial bite of the brakes, while the KTM PowerParts/Galfer Wave Discs improved the overall stopping power with the added benefit of significantly reducing the weight. For a while, I was satisfied with this arrangement. That is, until I rode the 2020 Triumph Street Triple RS, with its Brembo MCS master cylinder and M50 calipers. This started me thinking.

KTM 790 Duke R Project

The combination of EBC Double-H pads and the KTM PowerParts Discs delivered the additional braking power I was looking for.

At this point in the project, the combination of the OEM master cylinder, the EBC pads ($80), and the PowerParts discs ($458) provided more than adequate stopping power for hauling the bike down from speed. Still, I wanted more immediate application of the front brake with less free play in the lever. While I didn’t have the budget for a full Brembo system, including M50s, I decided to try a Brembo 17 RCS Costa Corta master cylinder to see if it would get me to where I wanted to be. Long story short, the 17mm piston was too small for the piston sizes of the J.Juan calipers, and I ended up using the Brembo 19 RCS Corsa Corta ($372). Now, I have the braking power, feel, free play, and adjustability I wanted all along. However, those M50s – or maybe some Stylemas – still call to me late at night, when I’m cruising the net…

KTM 790 Duke R Project

The Brembo 19 RCS Corsa Corta master cylinder provides a wide range of adjustability to suit riders’ needs. The power and feel at the lever are worth the cost.

MO Tested: KTM PowerParts Wave Brake Discs

MO Tested: Brembo 19 RCS Corsa Corta Master Cylinder

More Midrange

Don’t get me wrong, one of the 790 Duke’s strengths is its ample midrange for its displacement. That said, the more familiar I became with the LC8c engine, the more I noticed a slight softening of power in the 4,800-6,000 rpm range. I even used this dip as my around-town shift point for extra-smooth clutchless upshifts. Then, also, there was the matter of pride associated with the loss of 0.8 peak hp after installing the Akropovič “Slip-On Line” ($860) from the PowerParts catalog. (A fact that several of you MOrons roasted me for in the comments.) So naturally, I explored power upgrade options. A quest for redemption? I’ll let you decide.

KTM 790 Duke R Project

The key to more midrange: Dynojet Power Commander V and Rottweiler Performance Power Plate.

In the end, I settled on a Dynojet Power Commander V ($420), a Rottweiler Performance Power Plate ($100), and Rottweiler’s Street Map (Rottweiler maps are included with purchase of a Power Commander V from them) for my exact setup (Akra slip-on with Power Plate). The initial results were promising – with an extremely large caveat.

KTM 790 Duke R Project

The increase in midrange performance is visible on the dyno graph. What’s hard to see is that the torque peak has moved 1,100 rpm lower.

The good news was that, at every engine speed above 4,200 rpm, the Duke made more power. However, there was a puzzling flip side to my power modification that no one was initially able to explain. The problem was that from 3,000-4,200 rpm, at anything above 1/2 throttle, the engine fell flat on its face. Neither Dynojet nor Rottweiler have experienced this with any other 790 Duke. Long story short, the problem was caused by bad Power Commanders – yes, plural. Once a good one was swapped in, the 790 Duke put out the dyno graph shown here. The midrange received a 7% (3.5 hp) bump in power while the torque curve grew by a similar amount and had its peak come in 1,100 rpm earlier. Oh, and the Power Plate gives the engine a nice growl I can hear from the saddle without frightening the horses.

KTM 790 Duke R Project

The Akropovič slip-on looks and sounds nice, but it doesn’t provide any increase in power in it’s EPA-legal form.

MO Tested: Dynojet Power Commander V And Rottweiler Performance Power Plate For KTM 790 Duke

Weight Reduction

While I could clearly stand to lose a few pounds (like 20!), I would be remiss if I didn’t mention that many of the modifications I made to the 790 Duke also shaved off excess poundage. (Some changes, like the Evotech-Performance Crash Bobbins and Front/Rear Spindle Bobbins, added weight in exchange for their crash protection.) Some upgrades, like the PowerParts Discs and the Akropovič Slip-On, shaved pounds, 2.9 lb. and 2.1 lb., respectively, while most losses were in the ounces. Still, the changes add up and make a performance difference in every riding situation. Notably, the biggest weight savings on the 790 came from installing a Full Spectrum Power Pulse IPT P10L lithium battery ($219) that subtracted 4.9 lb. I left a couple of other weight reduction items on the table, though. Removing the catalyzer saves 6.0 lb., but makes the bike too loud for my tastes (that’s without considering the legality). Swapping out the stock wheels for forged ones saves weight and rotational mass, but this mod is beyond my means, right now. In the end, the bike weighed in at 398 lb. – down from the original 411 lb. – on the official MO scale.

The Hard Numbers

790 Duke R Costs
Suspension
WP Apex Pro 6500 Cartridges $879.00
WP Apex Pro 6746 Shock $1,099.00
Sub-Total: $1,978.00
Braking
AF1 Brake Line Adapter $35.00
Brembo 17mm RCS Costa Corta with Reservoir and Mirror Mount $450.00
EBC Double-H Pads (2 sets front and 1 rear) $117.00
KTM PowerParts Wave Discs $458.00
Sub-Total: $1,060.00
Power
Akropovič “Slip-On Line” $860.00
Dynojet Power Commander V $420.00
Rottweiler Performance Power Plate $100.00
Sub-Total: $1,380.00
Weight
Full Spectrum Power Pulse IPT P10L $219.00
$219.00
Performance Total: $4,637.00

The first thing you will notice is that the cost of these changes is significantly more than the price difference between the 790 Duke and the 890 Duke R (even when you add the additional cost of the Quickshifter+ and Track Mode for parity). This doesn’t surprise me since the economies of scale work in KTM’s favor. Go ahead and tease me about how I could have waited a year and just gotten an 890 Duke R. My coworkers certainly have with great enthusiasm. Still, making the bike I thought KTM should have built was never really the point. Instead, my goal was to build the naked parallel-Twin I’d always wanted, and the KTM 790 Duke turned out to be an ideal platform. I just wanted to spice it up a little. Plus, I had the pleasure of installing most of these parts myself.

Am I done with my 790 Duke Project? I think so.

Then again, the 890 Duke R’s flatter handlebar looks intriguing…

KTM 790 Duke R Project
KTM 790 Duke R Project

KTM 790 Duke R Project
KTM 790 Duke R Project
KTM 790 Duke R Project
KTM 790 Duke R Project

KTM 790 Duke R Project

The post KTM 790 Duke Project: Building A 790 R appeared first on Motorcycle.com.

Read more here

MotoGP NEWS FEED

Longhaulpaul: Ep. 15 of the Rider Magazine Insider Podcast

Longhaulpaul (Paul Pelland) and his Yamaha Ténéré 700 on the Bonneville Salt Flats in Utah. Our guest for Episode 15 of the Rider Magazine Insider Podcast is Longhaulpaul (Paul Pelland), a long-distance motorcyclist who is Chasing the Cure: riding one million miles to...

GP for the masses…

Way back in 2002 Ducati surprised the biking world when it showcased its new V4-powered sportsbike: the GP3. It was to hit the MotoGP scene in time for the 2003 season, with Loris Capirossi and Troy Bayliss atop this beautiful and capable bike that powered Loris to a...

2022 BMW R nineT/Pure

2022 BMW R nineT Pure. (BMW/)UpsNew Euro 5 cylinder heads produce better low-midrange torqueElectronic rider aids standard across all modelsUpdated rear shockDownsNo tachometer or gear indicator on Pure modelSeat uncomfortable on longer ridesFront suspension a bit...

Minibikes Draw Maxi-Attention at Barrett-Jackson Auction

This Honda CB175 was one of many small-displacement bikes sold at the Barrett-Jackson auction in Scottsdale, Arizona, January 22-30, 2022. Photos by the author. The Barrett-Jackson automobile auction is an annual extravaganza with a major stop staged at Westworld in...

2022 BMW F 900 XR Adventure Sport Review

We go for another ride aboard BMW’s easy-riding F 900 XR. (Joseph Agustin/)The 2022 F 900 XR is a plus-size middleweight adventure sport from BMW Motorrad. When BMW introduced this model for the 2020 model year, we were there for the official press introduction; see...

2021 Royal Enfield Meteor 350

2021 Royal Enfield Meteor 350 (Fireball trim) (Royal Enfield/)UpsThe beginner cruiser market gains one more competitorImpressive, well-balanced handlingEngine power may not be jaw-dropping, but its mild-mannered delivery and lack of vibration provides a very relaxed...

Ebike Maker Surron Announces First True Electric Dirt Bike

Surron’s first full-size electric dirt bike offering: the Surron Storm Bee F. (Surron/)If you stop and think too long about whether emerging EVs are bikes or motorcycles, you’re missing the fun. English EV maker Surron is a great example of blurring these lines,...

2021 Ducati SuperSport 950/S

2021 Ducati SuperSport 950 S (Ducati Red) (Ducati/)UpsUpdated electronics with Bosch six-axis IMU at the controlsNew windshield and seat enhance comfortA versatile and practical everyday machine with fantastic composure on the trackDownsLost a few horsepower due to...

2021 Suzuki SV650/X/ABS

2021 Suzuki SV650. (Suzuki/)UpsLow sticker priceFriendly yet peppy engineGood solid chassisDownsDesign is showing its ageA little heavyFront brake’s wooden response, numb feelVerdictAlthough it’s been usurped by newer competition, the SV650 is still a solid choice for...

2022 Suzuki Hayabusa GSX1300R Track MC Commute Review

In the motorcycle world, few streetbikes garner the type of attention as Suzuki’s Hayabusa. Long, low, and fast, the GSX1300R is the standard for motorcyclists looking to get somewhere quickly. The ’22 Hayabusa represents a modernized gentleman’s sportbike. Suzuki did...