INSIDE THE 2009 KTM 505XC TEST
You may be wondering why the MXA wrecking crew is testing an offroad bike instead of a motocross bike. The answer is simple: we absolutely love KTM’s big-bore 505 engine. In the past, KTM produced a 505SXF version for motocross racers. No more! Now the only way to get the big-bore 505 engine is to order the 2009 KTM 505XC-F. So, we ordered a 505XC-F and set out to turn it back into the 505SXF that we lusted after.
Amazingly, the transformation was quite simple. Which leads the MXA wrecking crew to the test of the 2009 KTM 505XC-F. Why the hubbub? Because this bike has one superlative that no other bike can claim?it has the best engine made.
Q: WHAT CHANGES DID WE HAVE TO MAKE TO TURN THE XC-F INTO AN SXF?
A: Before we reveal the list of changes, it is important to note that only a small number of mods were absolutely necessary (the rest of the changes were optional).
ON THE MUST-DO LIST ARE:
(1) Stiffer fork springs. The XC-F comes with softer fork springs and slightly softer damping. We upped the spring rates and turned the clickers in a couple of extra clicks.
(2) Stiffer shock spring. Although the 2009 KTM 505XC-F comes with the same spring 7.2 kg/mm rate as the 2009 450SXF, we don’t run that rate on the 450 either.
(3) Remove the kickstand. Although we kinda liked it, the race promoters didn’t.
(4) Gearing. Change the gearing to suit local conditions.
ON THE NOT-NECESSARY LIST ARE:
(1) Gas tank. Swap the big gas tank for the smaller SXF tank. This is not really necessary because the larger XC-F gas tank is so well designed that you can’t tell the big tank from the small tank when riding.
(2) Replace the 18-inch rear wheel with a 19-inch rear wheel. For Supercross or jump tracks this would be a big deal, but for most outdoor tracks the big 18-inchers is a passable tradeoff.
(3) Install an aftermarket pipe. The big-bore 505 engine has a great powerband, but it isn’t overly aggressive. Faster riders wanted more responsive power so that they could maximize each gear.
Q: IS THE 505 REALLY A HALF-LITER ENGINE?
A: No. Although KTM labels the engine a “505,” which would lead you to believe that it has a 505cc displacement, it doesn’t. The 505XC-F is really a 477.5cc. The bore is 100mm, while the 450SXF has a 97mm piston. Both the 450 and 505 share the same 60.8mm stroke. Just for chuckles, the 505 is a 29-cubic-inch engine, while the 450 is a 27.4-cubic-inch engine.
Q: WHAT DOES KTM’S BIG-BORE ENGINE HAVE TO OFFER?
A: If you’ve ever raced a 505, you would ask yourself why anyone would buy the 449.3cc version. The 505 is that good. The big-bore KTM engine does only good things to the KTM powerband. It is twice the engine of the 450. The power starts right off the bottom and just keeps pulling. It will run forever in a single gear (especially up in fourth and fifth gear).
This is the best engine made. The extra 27.2 cubic centimeters of displacement allow the 505XC-F to grunt off the bottom, pull taller gears, and produce the broadest powerband imaginable.
Q: DOES IT HAVE A FOUR-SPEED TRANSMISSION?
A: No. The 505XC-F and the 450XC-F have five-speed gearboxes (the 450/530 EX-C and 450/530 XC-W have six-speed trannies). The 450SXF is a four-speed.
Q: HOW DO THE GEAR RATIOS DIFFER ON THE SXF AND XC-F?
A: If you are comparing the 505XC-F directly to the 450SXF (gear to gear), you need to forget first gear and fifth gear on the 505XC-F. Why? Because first gear on the 505XC-F is very low compared to first on the 450SXF (which is more like second gear on the 505). Across the board, the gear ratios are not the same. As for fifth gear, it is much taller than the nonexistent fifth on the 450.
When you compare second, third and fourth on the 505 to second, third and fourth on the 450, you discover that the 450SXF has a taller second and lower third and fourth. This is to be expected, because the 505 uses its five speeds to achieve a very low first and a very tall fifth (and makes equal size jumps between second, third and fourth). As for the 450SXF, it has a tall first gear and narrower gaps throughout the range.
Both bikes use the same 14/52 final drive ratio and 29/74 primary drive ratio.
Q: WHAT DOES THE GEARING NEED TO MAKE IT BETTER?
A: We geared it down by one tooth. You might wonder how we could do that when first gear was already so low. Our answer? We don’t use first gear, and wanted to make third and fourth more usable (gearing the five-speed down one tooth makes its gears similar to third and fourth on the 450SXF).
Q: WHAT ABOUT THE JETTING?
A: We had no jetting issues with the 41mm Keihin FCR carburetor on the 505XC-F (not even the accelerator pump issues that bothered us on the identically jetted 450SXF carb). MXA‘s recommended jetting is as follows:
Clip position: Fifth from top
Fuel screw: 1?1/2 turns out
Notes: Last year the KTM 450SXF came with a smaller 40 pilot, but needed a 42. Now, the 450SXF comes stock with the 505XC-F’s larger pilot. Neither the 450SXF nor the 505XC-F have leak jets. An R&D Power Bowl2 can fix this.
Q: WHY ARE THE WHEELS DIFFERENT?
A: The wheels aren’t different, but the 505XC-F comes stock with an 18-inch rear wheel instead of the motocross-oriented 19-inch rim of the SXF. The larger rear tire is more popular with offroad riders because it has a larger air volume and footprint. The extra volume makes it more absorbent. The downside is that it bounces in squared-edged whoops.
The 505XC-F is equipped on the showroom with a Bridgestone 402 rear tire, while the 450SXF and 450XC-F use a Bridgestone M70.
Q: IS THE 505XC-F GAS TANK LARGER?
A: Yes. The 505XC-F gas tank holds a half-gallon more fuel than the SXF tank (it also has a two-quart reserve).
Q: HOW MUCH MORE DOES THE 505 WEIGH COMPARED TO THE 450SXF?
A: The 18-inch rear wheel, larger gas tank and extra gears in the tranny add eight pounds. Amazingly enough, it stills weighs less than a 2009 Kawasaki KX450F.
Q: WHAT WERE OUR BEST FORK SETTINGS?
Spring rate: 0.50 kg/mm (0.48 stock)
Oil height: 365cc
Compression: 14 clicks out
Rebound: 20 clicks out
Fork leg height: 5mm up
Notes: We ran the stiffer fork springs from the SXF model, but left the oil height alone. For 2009, KTM lowered the fork oil height from the year before enough to eliminate most of the midstroke harshness.
Q: WHAT WERE OUR BEST 505XC-F SHOCK SETTINGS?
A: As a rule, MXA has progressively been going stiffer on the shock spring every year…stiffer than stock. In 2007, the 450SXF came with a 6.6 kg/mm spring. We ran a 6.9. In 2008, KTM went to a 6.9 and we ran a 7.2 kg/mm spring. This year, the 450SXF comes with a 7.2 and we run a 7.6. This game makes no sense, except when you understand that every time we up a spring rate, the WP engineers match our move. So why do we keep going stiffer? Because WP keeps changing the shock setup to negate the spring rate changes. It’s like check and checkmate.
All of this leads us to the 2009 KTM 505XC-F shock. It comes with the same 7.2 kg/mm shock spring as the 450SXF. Of course, we prefer the 7.6 (for faster or heavier riders). For hardcore racing we recommend this shock setup for the 2009 KTM 505XC-F:
Spring rate: 7.6 kg/mm (7.2 stock)
Race sag: 110mm
High-compression: 1-1/2 turns out
Low-compression: 14 clicks
Rebound: 20 clicks
Notes: The 7.6 kg/mm shock spring is best suited to motocross, as opposed to offroad riding. We turn the clickers in a few clicks to compensate for the softer damping in the shock.
Q: WHAT DID WE HATE?
A: The hate list:
(1) Seat height. For a motocross bike, the KTM 505XC-F is too tall, which means that it is ridiculously tall for an offroad, enduro, hare scrambles or cross-country bike. Dangling your feet becomes second nature.
(2) Picking it up. We don’t want to grab the hot exhaust or the flexy fender to put our bike on the stand. Luckily, the 505XC-F comes with a kickstand. For motocross, we had to remove the kickstand and resorted to cutting the right side panel away to form a handhold.
(3) Hot-start lever. The plastic hot-start lever is prone to damage.
(4) Tires. KTM specs their motocross bikes with Bridgestone’s M59/M70 tire combo. The XC-F gets an M59/402 combination. We changed tires to suit the terrain, but the 18-inch rear wheel made available tire choices smaller (although the 18 did hook up better than the 19-inch in everything but rock-hard dirt and whoops).
(5) Graphics. Give us a Magic Marker and we can do as good a job as KTM’s design department did on the radiator’s shroud graphics. The typical KTM owner is older and more mature than the target audience for KTM’s cartoon graphics.
(6) Gas cap. The orange locking button does a great job of locking the gas cap on, especially when it gets gritty. We have actually had test riders who went to the starting line without checking how much fuel they had in the bike because they couldn’t get the cap off. We clip the locking tabs off with dykes.
Q: WHAT DID WE LIKE?
A: The like list:
(1) Handling. The KTM 505XC-F corners really well, in part because of the softer suspension, but largely because KTM has successfully put their understeering past behind them.
(2) Fork guards. The wraparound guards do a great job of keeping rock dings (from your competitor’s rear wheels and your own front wheel) from ruining the fork legs.
(3) Plastic frame guards. KTM’s frame guards protect the frame from scratches.
(4) Compression adjusters. The new dials are easier to turn.
(5) Electric starter. Forget fuel injection; what the motocross world really needs is electric starting. This is especially true for professional motorcycle racers (who can ride fast, but can’t start their bikes).
(6) Front brake. KTM should get a medal for being brave enough to mount brakes that actually work. Super brakes.
(7) Hydraulic clutch. Love it.
Q: WHAT DO WE REALLY THINK?
A: Great engine. So great that the MXA wrecking crew was willing to take the offroad-focused XC-F package to get our hands on the 505 powerband.
For more info go to www.ktm.com