KTM 300 XC Race Bike Build


This article was originally published in the June 2017 issue of Dirt Rider.

Prior to riding the stock 2017 KTM 300 XC and XC-W I was admittedly not a fan of 300cc two-strokes at all. But after riding the ’17 models, my whole outlook of the big-bore two-stroke class has changed; with a smooth engine that has less vibration than most 125cc bikes, the next generation of two-strokes looks quite promising. Seeing as how the new KTMs are on the top of my list of favorite 2017 bikes, I was thrilled to get a text from Chris Blais asking if Dirt Rider would be interested in testing his 300 XC that he had built for up-and-coming off-road racer Kyle Mercier to contest the WORCS series and some NHHA events. We hammered out the details, and the next thing I knew there was a gorgeous 300 XC sitting in my garage waiting to be ridden.

If you aren’t familiar with Chris Blais, do yourself a favor and watch the movie Dust to Glory. Chris was a very accomplished desert racer, Baja racer, and Dakar podium finisher in 2007 before having a bad crash that left him paralyzed. But that hasn’t slowed him down. Since his accident he has raced UTVs, as well as other four-wheeled vehicles, and he now runs a motorcycle repair shop and KTM-based race team out of his Apple Valley, California, home helping up-and-coming racers make a name for themselves.

Chris started with the already great KTM 300 XC and set out to make it competitive against the 450cc four-stroke machines in the Open class of the WORCS and NHHA series. The first step in a true bike build is to take the motorcycle all the way down to the frame and rebuild it while improving existing parts and replacing some OEM parts with better aftermarket units. One problem with the 2017 KTM two-strokes is that the new Mikuni carburetors can be a bit finicky. Blais fixed this by replacing the stock carb with a 38mm Keihin PWK Air Striker unit with his specific jetting settings. This, along with custom cylinder porting, VForce reeds, cylinder-head modifications, an FMF pipe and silencer combo, and a CDI upgrade made the 300 into a real fire-breather.

In the suspension and chassis department Blais didn’t pull any punches. Race Tech provided all the internal suspension parts, which were then tuned for the demanding off-road courses by ESR suspension. When I rode the bike, it was on its third suspension refinement, as the Race Tech folks had been working on getting more plushness in the air fork. Fasst Company Flexx Bars were installed to soften the harsh blows of a choppy GP course, as well as a Fastway steering stabilizer, linkage guard, handguards, and its Air Ext footpegs. Bullet Proof Designs provided the radiator guards, sharkfin, and swingarm guard to help protect the machine from rocks. New Excel A60 rims were laced up to Tusk hubs with Buchanan’s HD spokes, and they were all wrapped up with Kenda Washougal tires front and rear. The finishing touches included items like a Seat Concepts seat cover, IMS 3.2-gallon tank with dry-break receiver, and Megla Designs graphics kit.

I knew going into this bike test that I was already fond of the KTM 300 in stock form, so I was excited to see what a full race version of an already great bike would be like.

In the engine department it was no surprise the Blais-built bike had more than enough horsepower to run with 450cc bikes. Being that the bike was built for pure performance and fast-pace racing, some of the very smooth stock roll-on power off the bottom was missing from the full racebike. That’s not to say there was no bottom-end; it was just not quite as smooth and friendly as the stock bike’s. Once into the mid to top, I quickly learned to hold on tight because the power came on hard, and if I wasn’t careful, either the front end was coming up or the rear end was power sliding. The Blais bike, when ridden in the higher part of the midrange, was at its happy place where power was available at any time. The fully built engine also had more over-rev than the stock engine and didn’t sign off in the power-making department like stock 300s; instead it pulled for much longer, sounding like an angry bumblebee.

I was concerned before the ride that a fully built racebike might vibrate more than the buttery smooth stock bike, but to my surprise Blais’ bike was just as smooth.

Keeping in mind what this bike was built for, the suspension was flat-out impressive. WP has, in my opinion, the best air fork on the market, and every time I ride one I’m surprised at how well air can work. The stock 300 XC fork has good settings but is a little springy (or fast) feeling and lacks initial plushness when in rock sections. Being that Blais’ bike was built for fast GP and desert racing, the bottoming resistance when landing into a G-out or large jump is fantastic and doesn’t deflect like the stock fork would. For me, the fork is a tad on the stiff side when it comes to braking bumps or rock gardens, but then again, let’s be real, I’m no longer a 20-year-old kid pinning it across the desert.

Out back the shock has a very positive, progressive feeling that never seems to skip around or bottom harshly. Both ends of the machine truly surprised me when it came to bottoming resistance. It seemed that no matter how hard I landed, the last few inches of travel were so progressive that there was never a harsh bottom-out.

The steering on the bike had the best of both worlds—feeling nimble at slow speeds when the trails were tight and also remaining stable when the trails opened up. I think the combination of good suspension settings as well as the Fastway steering stabilizer helped keep the front end in line. Another place I felt the 300 was comfortable and predictable was in flat turns, which is not common for two-strokes. It seemed that once I broke the rear wheel loose, with a little modulation of the throttle I could keep a perfect slide throughout flat, slippery corners.

The Blais 300 XC was definitely more at home at speed than in tight, rocky areas. The power and suspension were both a little aggressive to be comfortably lugged through extreme enduro-type terrain. But when it came time to be opened up across valleys and on motocross-style tracks, the Blais machine showed its true colors. Some people think that 300cc two-strokes are only meant for tight, snotty, nasty conditions, but Chris Blais has proven that a well-built 300 XC is a force to be reckoned with. Blais’ theory on building two-stroke racebikes is that they are cheaper to maintain throughout a season than most four-strokes. Don’t get me wrong; this 300 was no cheap build, and replacing two-stroke pipes isn’t cheap either, but now that it’s built, top ends are cheap to replace when compared to top ends on four-strokes, in both time and money. And let’s be honest, who doesn’t enjoy smelling two-stroke race gas while hearing a crisp 300 racing wide open across the desert?