Long-Term KTM RC390 Project: The RC390 Goes Racing

WRIST: Ari Henning
MSRP: (2015): $5,499
MILES: 2,966
MPG: NA
MODS: Bridgestone tires, suspension and gearing changes

With the word "Racing" emblazoned on the long-term RC390's engine cases in bright orange and the slogan "Ready to Race" popping up on the LCD dash every time you turn the bike on, we all knew it was just a matter of time before this small-bike spaz gridded up on his long-term KTM.

Pretty much all the work I’ve done to the RC thus far has been to prepare it for a life as an apex hunter. I tested things out at a few track days, but finally it was time to slap on some numbers (but just tape the lights, because I still want to ride the KTM on the street!) and take it racing.

Well I finally did, I had a blast doing it, and I even brought home some trophies. The grids at my local club, Chuckwalla Valley Motorcycle Association, are huge and populated by some of the most enthusiastic and entertaining people I’ve ever met. Everyone was excited to see how the RC would do, but nobody was more excited (nervous, really!) than me.

I qualified on poll so I had the benefit of starting from the front row. The RC has good torque and a smooth clutch so launching it is fairly easy, though that little digital tachometer isn’t ideal for racing—I definitely prefer an analog readout. In all three races I ran I had to contend with hoards of Yamaha R3s, Ninja 250s and 300s, and lots of other RCs. The KTM pulls on the other bikes (including the RC390 Cup bikes, which are limited to 38 hp) so I had that going for me, but I was struggling to maintain corner speed due to some rear-end chatter. Even so I managed to take the win in all my races, though the last one, against my friend Jason Madama from Colorado on his R3, was really close!

For this outing I levered on a proper race front tire (a Bridgestone R10 Type 4, in 120/70-17 size) to compliment the 140-series RS10 I recently evaluated ( click here for the MC Tested ). I've been working on improving front-end feel, and I wanted to put a really sticky tire on to eliminate rubber from the cornering equation so I could focus on the chassis. Right away in practice I experienced much better front-end feel, and with some additional front ride height, turn-in stability and feedback improved even more. Awesome! I finally have the front end sorted and feeling good.

The rear end, however, is now an area of weakness. As soon as I’d tip the bike into a corner the back tire would chatter and want to come around, so I had to be cautions until I could get on the gas. The RS10 rear has ample grip at corner exit, so clearly this traction issue is the result of a suspension or weight imbalance. Needless to say, that’s where I’ll be focusing my attention for now. Maybe it’s time for a slipper clutch?

Other things I changed this weekend were my gearing (from a 44 to a 46) and the length on my JRi shock. I added 8mm of rear ride height to get more cornering clearance on the pipe side of the bike—I'm running a beautiful MIVV pipe from mnnthbx.com and it's getting ground down. I also bolted on a Tyga belly pan and rearsets from formula390.com. The Tyga bodywork is top notch, and only a fraction of the price of the factory KTM parts. The race club's rulebook says you need a fluid-retaining belly, plus it's a convenient place to put stickers. And come on, it's not a racebike without stickers!