MXA BUILDS A KTM 450SXF THAT’S TOO FAST FOR MORTAL MEN
Factory Effex did the very attractive orange/blue color combo for the graphics on our KTM 450SXF.
“This bike is just too fast for me,” isn’t something you hear every day from the MXA wrecking crew. “Too slow,” “Too stiff” and “Hits too hard” are the common refrains from this group. When a bike is too fast, most MXA test riders can’t wait to get their hands on it to see what kind of “too fast” it is. Is it 2018-Honda-CRF450 fast, where you think each lap might be your last? That engine was super fast, but the CRF450’s unbalanced chassis couldn’t handle the abrupt powerband. Is it Kawasaki-KX500 fast? That is faster than only a few want to go. Or, is it Eli Tomac fast. Tomac is one of the few riders on the Professional circuit who wants his bike to be as fast as they can make it.
It didn’t have a rip-your-shoulders-out-of-their-sockets, too-fast sensation. Instead, the power snuck up on you. When in Map 1 of the Twisted Development-programmed Vortex ignition, our KTM had a nice, solid pull off the bottom. It was very manageable and smooth, but the power ramped up significantly as the revs increased. The sudden acceleration caught the MXA test riders off guard due to the smoothness of the low-to-mid transition. Once it got into the meat of the powerband, it was too late to do anything about how fast you were going. Most test riders described it as much faster than they planned to go. The power was deceiving. It didn’t hit hard like the 2018 CRF450; it was more of a KX500 type of power where you didn’t realize you were going that fast until you were going too fast. Tester after tester came off the track and said, “It’s too fast!” When we asked why, it wasn’t because of ill handling or because it hit too hard, it was simply because they got going faster than they were comfortable with. They were over-jumping, braking harder to make corners, going over berms from overcooking the straights and wearing themselves out from hanging on. The more experienced MXA test riders rode the 450SXF a gear high, which toned the velocity down and made it much easier to ride.
When we gave our 2021 KTM 450SXF engine to Twisted Development, we told them not to hold anything back. In case you don’t know, Twisted Development is the mapping king of modern ECUs. We weren’t scared, because we knew that if it truly turned out to be too fast, Jamie could tone it down as much as we wanted. When Twisted Development’s Jamie Ellis gave the engine back to us, he said, “All right, on the dyno, it is about 3 horsepower more than what Broc Tickle ran for his 2021 Supercross setup and about 8 horses more than Josh Mosiman’s Husqvarna FC450 National bike you tested back in 2017.” As an aside, Josh thought the bike Jamie built him in 2017 was too fast!
This was not an inexpensive build. We could have been happy with something that was much more affordable, but what fun is that? Twisted Development is one of a small handful of engine builders that can build an engine that is competitive against the factory efforts (and they are willing to offer it to the public).
THE SUDDEN ACCELERATION CAUGHT THE MXA TEST RIDERS OFF GUARD DUE TO THE SMOOTHNESS OF THE LOW-TO-MID TRANSITION.
We didn’t stop at the engine. We insisted on putting on Brembo Factory brake calipers, which run over $1000 a pop, front and rear. These are Brembo works brakes from a few years ago, and in previous tests we learned that they are much better than Brembo’s OEM brake setup. You only get the calipers when you buy the Factory setup from the KTM Power Parts catalog. The brake lines, master cylinders, crush washers and banjo bolts are separate, but you can use the existing parts from your bike to put to them together. If you don’t feel comfortable doing this, pay a good mechanic to do it right. One thing that is super cool about the factory calipers is that they have a serial number stamped in that you can use to log onto the Brembo database to ensure these are the real things and not knockoffs. The database shows you where and when they were made. If your serial number doesn’t show up, you have been duped.
Most riders didn’t mention the factory Brembo units on their first couple rides, which we took as a “no news is good news” situation. But, the faster the test rider, the more he raved about the brakes. They didn’t heat up like the stock brakes. There was no squealing or chirping, and they had much better modulation at the lever and pedal. For most weekend racers, these expensive brakes ($2000 for the set) are just for bragging rights. But, for AMA Pro racers, these brakes are what make the difference between first and second place.
We kept the stock WP suspension components, but we had AHM Factory Services anodize the fork legs, black chrome the shock shaft and re-valve them for us. If you look closely, you can see that we used 2021 Husqvarna Rockstar Edition wheels and triple clamps, also available in the Power Parts catalog, to give our KTM 450SXF some blue highlights. We also bolted on a Power Parts Akrapovic exhaust system, but this wasn’t our first choice. Both FMF and Pro Circuit were fresh out of systems.
But, there was an easier fix. When we sent each test rider back out on the track, we switched the Vortex ignition to Map 2. Suddenly, they loved the power. It was much more manageable than Map 1. In truth, some test riders still thought it was too fast, as the power would still sneak up on them. Map 2 was a mellower map that offered a very connected feel. It tracked the ground like glue when accelerating out of corners. It had a traction-control-like feel—in a good way. Map 2 minimized mistakes and was easier to ride longer in the moto. For the test riders who felt our KTM 450SXF was still “too fast,” we engaged traction control with Map 2. This toned down the power just enough that it wasn’t overbearing at speed. This combo map suited our Vet test riders well.
A SEA CHANGE IN SUSPENSION
In what is a sea change in the suspension world, the MXA test riders have been thrilled with every set of 2021 WP XACT air forks we have ridden with this year—and we have tested a boatload of 2021 KTM, Husqvarna and GasGas machines. They are the best production air forks ever, because they feel more like spring forks than any previous air fork. How much they closed the gap on Kayaba SSS forks in one year bodes well for air forks in the future. Our initial response to the AHM valving was that it was too soft, causing the front to dive too much on corner entrance. We upped our 10.7 bar (155 psi) in the forks to 11.0 bar (159 psi), went in three clicks on the shock’s low-speed compression damping and lowered the sag from 100mm to 103mm. This balanced out the bike better and kept the forks from diving. What our test riders liked about this AHM setup over stock was that the initial part of the travel was plusher. It soaked up chop and stutter-style bumps and didn’t lose any hold-up in the mid-stroke. The forks also offered improved bottoming resistance, which was a plus.
WHAT DID WE REALLY THINK?
We think only a few could ride this MXA project bike to its potential; however, every test rider—from slow to fast to young to old—preferred this bike over his own personal steed. He just didn’t want to pay the price that came with ownership. This project bike exemplifies the gap between the haves and the have-nots. We bought power and brakes that only a Pro could use to their fullest potential, but we couldn’t buy the talent to use them to their fullest. Strangely, it was reassuring to our slowest test riders that all that power was there if they needed it—and were brave enough to use it.
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