The world of legalized off-road riding is riding a tsunami of evolution that is driven by the demand for open riding areas and the ability to actually get our dirt bikes to them. There is no doubt that the noose continues to tighten on trail availability, which in turn has upped the demand for street-legal dirt bikes. The KTM EXC has pushed this progress. It is made for the dirt soldier who can now “get there” on a machine that is tarmac legitimate and trail savvy.
In our world (California is known as the state of “can’t”), it has gained an impressive following of hard-core riders who also love to tinker, accessorize and improve their equipment. Because the machine is EPA legal, it comes with equipment that targets sound and emissions, two areas that are vital to the future of this machine. Our performance mods centered on improving the fuel flow to the throttle body and giving the very closed stock muffler end cap some adjustability, not altering the emissions or the ECU. Over the last year we’ve tested gearing changes, handling updates and big suspension modifications, and have found a number of aftermarket products that improve ergonomics, durability, comfort and traction.
IMPROVING THE ANGLE OF THE DANGLE
First off, we’ve ridden our 500EXC for the entire year with the engine stone stock, the only mod being a CARB-legal Akrapovic titanium muffler. The power is strong and the exhaust note is almost silent. Dave Simon over at BestDualSportBikes.com upped the ante with his new Fuel Rail, an ingenious modification that quite simply straightens out the fuel’s path to the fuel injector. Stock, the fuel’s journey is hindered by sharp bends and odd angles, which not only has a dramatic effect on top power (it actually leans out from a lack of fuel) but stifles the roll-on and midrange. The revised Fuel Rail improves throttle response pretty much throughout the powerband. For $79.99, this may be one of the best mods that we’ve done to the 500! On the downside, it’s not an easy bolt-on task. It requires that you peel off the tank, subframe, pipe, shock and airbox to gain access to the stock fuel rail. But trust us, it is worth it!
Best Dual Sport Bikes also offers an adjustable end cap that has an enlarged chamber to bounce the exhaust sonics (for less noise). Plus, it has a removable exhaust snout that in quiet form nearly matches the super-stealthy stock end cap and offers a power gain. If you remove the quiet insert you will get a decibel increase (it will measure very close to a stock XC-W muffler), but you’ll also receive a strong power gain. For all of our dual-sport activities, we kept the quiet insert in place, preferring the stealth factor.
Our last power mod was replacing the stock header with an FMF MegaBomb. The FMF system is two pieces (and far easier to remove than stock) and improves roll-on and mid-range power. The power comes courtesy of a smaller head pipe that mates to the centered MegaBomb, which not only staggers the exhaust note for noise reduction but helps improve its out-of-the-hole throttle feel. We actually had to cut about 9mm off the end of the FMF MegaBomb in order to use the stock muffler. Rumor has it that FMF is slated to offer one that will work with the OEM unit in the near future.
THE SEARCH FOR SUSPENSION NIRVANA
In stock trim the KTM EXC suspension gets good marks for being plush and trail-worthy. Up until recently we’ve ridden with it stock but equipped it with stiffer springs, fore and aft. The machine is big (258 pounds sans fuel), and when you start pushing it in rough terrain it gets ponderous and spooky, as both ends bottom too easily. Out back the PDS link-less suspension is good in rocky terrain, gets wallowy in whoops and tends to stand up on big downhills. We lived with all of this just fine—until Adam at Kreft Suspension told us that he could make the stock WP dampers dance.
Remember the wallow, dive and bottom mode we talked about? The Kreft-modded suspension, albeit an expensive and comprehensive change to the WP dampers, gets the suspension to walk the line between enduro plush and desert firm. Is it as cushy as stock? No. But it still chews on hack, rocks and roots quite adeptly and will do it at speeds that make the stock dampers cringe. The Kreft-equipped fork stays up far better and resists diving. The valving accepts trail input and responds with a firmer, more planted and balanced appetite. The bottom line is that the fork takes on a much more versatile nature than simply “enduro cush” mode.
We were pleasantly surprised with the PDS shock’s improvements. It feels tighter (not so loose and reactionary) and really helped the rear wheel hunt for traction, both in acceleration and braking. And similar to the fork, the shock has far less wallow to it, preferring to stay up and valved to greet the off-road world’s larger hits and speedier terrain with far more control than stock.
BOLT-ONS, TRACTION AND FEEL
Here’s a hit list of what ended up on our 500EXC. Each and every part got the Dirt Bike “try to roach it” test and passed the evaluation.
The cockpit: We ended up fitting on an ODI Controlled Flex handlebar, the McGrath bend. It’s super strong and has a good feel courtesy of the crossbar (it actually lets the bar flex during impact). We added ODI MX V2 half-waffle, lock-on grips that have an absolutely superb feel and mount easily, and we also added Best Dual Sport Bikes’ dead-ends. These help to reduce the vibration of the big 500 and are a pain to install but worth the price of admission. The final mod was Moose Racing’s bar risers (5–30mm), which let us move the bar 10mm up from the triple clamp—totally necessary for our tall guys!
In the saddle department we have used Seat Concepts’ foam and cover all year. The seat is wider through the middle, disperses the load for long hauls far better than stock, and has a foam density and cover that actually help you make traction with your fanny. This a must-have for the dual-sport/long-haul off-roader.
We ended up with 14/50 gearing for our 80-percent dirt/20-percent street rides and 14/48 for our 60-percent dirt/40-percent street escapades. This allowed us to just flip the axle and have the chain blocks fit both sprocket sizes without us having to change the adjustment. We’ve been abusing a Renthal Twin Ring sprocket and O-ring chain all year with great results; the 48-toother has just enough top speed to let you cruise at the speed limit without making you feel like you’re gonna smoke the motor.
And while it seems like every single project machine we build gets the TM Designworks’ guide and slapper kit, there’s a reason: They’re gnarly. They last. They love to get smacked around, and they don’t break.
We’ve been testing quite a bit with the Goldentyre 90/100×21 GT 216AA front tire with great results. The DOT/FIM-legal tire is large (both wider and taller than a normal motocross knobby) and seems to really help in loose, sandy terrain. It has a strong, stable grip that lets the bike track and not knife in. It’s super popular on the European World Enduro scene, and Ty Davis is the man who turned us onto them. It works very well with the Goldentyre mousse, and while foam inserts are a pain to install, they make for a ride where you can attack all obstacles and never fear the flat.
Out in the backyard we really prefer to run DOT-legal tires, and once again the Goldentyre boys have some great rubber. We’ve run both their GT523 Hard (shorter knob and a 140/80-18) and their 523KX Gummy, which is a total cheater tire. It’s sticky with super-pliable knobs and craves ugly conditions. The 523 Hard is more durable, still has superb traction and lasts longer when you have some asphalt transfer zones. And as in the front, we’ve been running the Goldentyre mousse inserts. Taking flats out of the mix is nice! The Goldentyres are not cheap, but they work and are street-legal. We get ours from www.aomc.com.
THIS AND THAT
We fit up a Rocky Mountain ATV/MC inner rear fender and turn signals. The unit is far more compact than the low-hanging KTM unit, and the turn signals are smaller and tuck in far better.
In an effort to increase legroom, we fit on a pair of Raptor titanium footpegs that are 5mm lower than stock. These things are flat cool, weigh nothing and offer incredible grip. They are super pricey but trick beyond belief. We got ours from Pro Circuit (www.procircuit.com), and they nick you for a nickel under 350 dollars.
AND LAST ON THE LIST…
The KTM 500EXC makes us smile. It lets us travel, explore and still chew on terrain that prefers a real dirt bike. Our modded machine far out-handles the production machine, and while all of our emissions and ECU settings remain stock, we’ve gained a more acceptable and usable powerband while keeping the noise footprint brilliantly stealthy.