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We Build a KTM Factory Edition Killer | Twisted Development 450 SX-F


The 2020 KTM 450 SX-F is an incredible machine in bone-stock condition. It’s got a monster powerband with a good deal of adjustability thanks to its dual map switch and traction control settings, excellent handling characteristics, and good suspension that offers a wide range of adjustability. With the release of the 2020.5 Factory Edition a few months later, we got the itch to see how easy it would to make the standard bike into a superior machine, with some mild engine and suspension work. For around $2500 for a Stage 1 Engine Package from Twisted Development and a suspension rebuild from REP Suspension that included a WP Spring Conversion Kit, our test bike stood head and shoulders above the refined 450 SX-F Factory Edition bike. Of course, we couldn’t stop there so we added some more performance parts that we knew would benefit the overall performance of the bike, and finished it off with some cosmetic upgrades.

The finished project is a dream build if we’ve ever seen one. The result of our build is a 2020 KTM 450 SX-F that has loads of usable power, handles exceptionally well, is comfortable and confidence-inspiring, and great-looking to boot!

The Build

The first step in our build was dropping the bike off with Jamie Ellis at Twisted Development Racing. Through the years, Ellis has built a stellar reputation as one of. the premier engine builders in the sport, whether the engine is two-stroke or four-stroke. It’s no coincidence that Twisted Development is the builder that factory riders turn to when it comes time to put together their own race effort; Davi Millsaps, Justin Barcia, and more have all headed straight for TD’s Murietta, California, headquarters in search of more power. Twisted’s Stage 1 Engine Package includes CNC head porting and decking, as well as reshaping of the valve seats to allow for greater flow when the valves open. Lastly, Twisted has the capability to reprogram the stock ECU, and can load up EFI maps to perfectly suit your riding locale and style. 

An FMF exhaust system is an easy choice. Built in the USA, lighter than stock, better looking, and better performing…what more could you ask for?

An FMF Factory 4.1 Megabomb titanium and carbon fiber system was chosen to route the spent fuel vapors out the rear of the bike, and we’ve already had great luck with this system on virtually every 2020 machine made so it was a no-brainer. FMF systems fit perfectly, improve power, and cut weight. What more could you ask for?  Putting the power to the ground efficiently is just as important as having more power on tap, and that’s where a Rekluse TorqDrive Clutch Pack comes in. The system bolts right into the existing clutch basket, but utilizes 12 thinner friction and 12 thinner steel plates as opposed to the 8/8 stock clutch. The result is instant torque and throttle response…trust us, it is unbelievable! You don’t realize how much a stock clutch slips under acceleration until you try a TorqDrive assembly…it’s mind blowing! 

The top left fork cap is the giveaway: gone is the air valve and it is replaced with a mechanical spring preload adjuster. The crew at REP Suspension are masters at tuning suspension of all bike brands…they tune Broc Tickle’s JGR Suzuki!

While the bike was at Twisted, the fork and shock were removed and sent to AEO Powersports, a KTM and Husqvarna dealership in Murrietta that has an in-house suspension shop, Research Engineering Performance. In addition to revalving the fork and shock to match our specified test rider height, weight, and ability, they installed a WP Spring Conversion Kit, which replaces the air spring component of the Xact48 fork with a single-sided mechanical spring system. 

KTM Powerparts Factory Triple Clamps offer an adjustable steerer tube and have a unique clamping system that evenly places the clamping force on the upper fork tubes.

To further enhance the bike’s handling traits, we decided to add two more key components that we have been impressed with in the past: a KTM Powerparts Factory Triple Clamp and a set of FCP Racing engine mounts. Standard on the Factory Edition bike, the bright orange clamps offered by KTM in its Powerparts catalog feature a reversible stem that offers both 20 and 22 mm offset settings. The split clamp design eliminates binding in the fork tubes as they apply more even pressure when cinched down. Best of all, the clamps look absolutely badass and add some adjustability, too.

Peek behind that FMF Megabomb header and you’ll see the FCP Racing engine mounts. The billet aluminum mounts allow more flex and deliver a more comfortable ride.

The billet aluminum FCP Racing engine mounts, meanwhile, allow a bit more torsional flex than the stock cast parts and this allows the chassis to have a plusher feel and greater comfort in acceleration and braking chop. Furthermore, they allow the already great cornering KTM to lean over with even more control and predictability in rutted corners.  

RC bars inserted into Emig grips…there’s a tasteless joke in there, somewhere.

For controls, we turned to ODI for a pair of Podium Flite Bars in the new RC4 Signature bend, and paired them with Emig Pro V2 Lock-On Grips. Even though they’ve been in the broadcast booth together and team up for the 447 Real Talk Podcast, it still seems odd to pair signature products from the two fierce rivals of the 2000s. Nihilo Concepts is a Florida-based company that produces all sorts of super-trick parts for all kinds of off-road vehicles. An importer and distributor of the Raptor Titanium pegs from the UK, Nihilo went several steps further with its line of Nihilo One-Piece Titanium Pegs. Carved out of a single chunk of billet titanium, the pegs are 1/2″ wider than stock, super sharp, and weigh in at 5.3 ounces less than the stock titanium cast pegs! While one could certainly argue that we didn’t need these $799.99 pegs, holding them in your hands first, and then riding on them, would have you anxiously saving your pennies. Without a doubt, these are the trickest aftermarket pegs we have ever encountered!

Nihilo One-Piece Billet Titanium Pegs…they feel as nasty as they look!

To finish off the Factory Edition Killer, we ordered an all-orange plastic kit from our friend Brian Fullerton at Acerbis. The Italian plastic fits as perfectly as OEM, has a deeper hue of orange, and in our experience has proven to be more durable. We rewrapped the seat with a 6-Rib Cover from SDG Innovations and finished the project with a custom set of Backyard Design graphics. Printed on proprietary vinyl. BYD graphics are remarkably easy to install, stay adhered to the bike, and look great.

We’ve relied almost exclusively on SDG USA seat covers for years. Try one and you’ll understand why.

On the Track

For as many bikes as we’ve built over the last two decades, it never gets old taking one out to the track for the first time. This is how factory riders must feel at every race, walking up to an immaculately prepared machine that is sure to work every bit as great as it looks. When all was said and done, our Factory Edition Killer was a real looker, and we couldn’t wait to get it out on the track. Our tester was our friend Matthew Horton from Mesa, Arizona, an already loyal KTM Factory Edition rider and racer.

Matthew Horton

From his first laps, Horton was very impressed with the machine, even though it felt much different than his personal FE. The roll-on power was impressive, especially so thanks to the Twisted mods and Rekluse clutch. Matty commented that he had to rethink some of his acceleration and shifting points, as the bike pulled harder, sooner, than he expected. The massive low-end power of the bike transitioned smoothly into a massive mid-range punch that was exciting yet controllable, and the power continued to pull into the upper echelons of the RPM range without falling flat. The bike took on a deep, throaty exhaust note that turned heads in the stands, and it made us wonder just how gnarly a Stage 2 or 3 engine package that utilized race gas would be!

Matthew Horton

It’s no secret that we are not fans of air forks, and even though the WP Xact 48 was the best in the “air fork revolution,” they remain the sole survivors as all of the Japanese brands have returned to the more consistent and comfortable mechanical spring design. Even though we are also not fans of the single-function fork design introduced by Showa years ago, we must admit that the WP Spring Conversion Kit – though it is single-sided with one spring – feels amazing! Combine d with the custom tuning by the REP Suspension experts, the spring conversion kit brought a level of comfort and predictability to the front end of our KTM that we’ve previously only encountered with the high-dollar Cone Valve spring fork setup. The front end of our KTM excelled in small braking chop and maintained great front-end feel and traction entering corners, resisted diving mid-corner, and tracked true with great grip on the exits. The revalved shock was well matched to the fork, and the overall balance was very good with no see-sawing front to rear under acceleration or braking. All told, this is one of the best-handling KTMs we’ve thrown our legs over. Of course part of that can be attributed to the FCP engine mounts, which we already knew would improve the bikes’ feel entering, negotiating, and exiting corners. It’s remarkable what a large effect such small parts can have on the way the entire bike performs.

So, you ask: does our project bike surpass the performance and feel of our 2020.5 Factory Edition test bike? If the answer to that question isn’t painfully clear by now, we’re either crappy writers or you need to take a class in reading comprehension! 

Twisted Development Stage 1 Engine Package – $850

Twisted Development ECU Reprogramming – $250
Twisted Development Base Gasket – $50
KTM 125 SX Air Filter Cage – $25 
AEO PowerSports/REP Suspension revalve – $500 plus parts
WP Spring Conversion Kit – $675
FMF Racing Factory 4.1 RCT Titanium/Carbon System – $1049.99
Rekluse TorqDrive Clutch Pack – $249.00
KTM Powerparts Factory Triple Clamp – $623.99
Acerbis Full Plastic Kit – $199.95
SGD USA MX 6-Rib Cover – $69.99
ODI Emig V2 Pro Grips – $28.95
ODI Podium Flight Bars RC4 Replica Bend – $99.95
Factory Control Parts Engine Mounts – $399.99
Nihilo Concepts One-Piece Titanium Footpegs – $799.99
Backyard Design Custom Graphics – $229.90
Donn Maeda

Donn Maeda is a 30-year veteran in moto-journalism, having worked at Cycle News and Dirt Rider before launching MXracer Magazine and TransWorld Motocross Magazine. Maeda is the Editor-In-Chief at Swapmoto Live and you can catch him on a dirt bike or in the saddle of a mountain bike on most days.

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