While many OEMs are dropping their 2-stroke lineup like a sack of steamy poo, KTM keeps developing better ring-dingers, and offering options for the smokin' faithful.
Ah, the dog days of summer- the time of year when we all kick-back and enjoy long, sunshine-soaked days out riding. Yep, summer means Motocross First Rides-the most anticipated time of the year for this scribe.
MotoUSA got a chance to sample Austria's latest and greatest lightweight 2-cycle weaponry; the KTM 125SX and 144SX at the fast and bumpy Glen Helen Raceway in San Bernardino, California. Conditions at the 22-year-old AMA-spec track were hot and dry-ideal for those who are down for sweating out a gallon or two.
Thundering 4-stroke motocross bikes are everywhere these days. Just pause your iPod for a moment and you'll hear the throaty thump that permeates the air at tracks and race starting grids throughout the country. So why then does KTM continue to tweak its 2-stroke machinery? For starters there is a certain segment of the market that still yearns for an affordable, feather-light, easy to maintain, race-ready motorcycle. Another draw is that these bikes are adaptable to a variety of different roles that reward lightweight machinery i.e., technical off-road and enduro racing. They also make a great choice for vertically challenged people and serve as a stepping stone that fills the gap between a smaller junior machine and a full-sized motocross bike.
At first glance the 125 and 144 look identical in their new-for-'08 livery - which looks fast even at a stand still. In fact, the only way to tell the two apart is from the bikes displacement markings in the graphics and the slightly different expansion chamber design.
KTM has always been known for its potent 2-stroke mills and this year's engine is no exception. The Austrian engineers focused on getting a wider range of power out of the eighth-liter premixer. The biggest change to the 125 is its reshaped piston. The little engine churns out power and has a snappy mid-range that transitions into a wheel-spinning power surge up top. All day we raved about the relatively wide powerband of the 125.
"The engine has a broad powerband with plenty of power from mid-to-top," comments MotoUSA's motocrosser extraordinaire, Alvin Zalamea. "The motor is strong in every part and feels like a full mod bike from back in the day. For a production motor I'm surprised how fast this bike held up with the 250Fs."
The 144SX has a definite advantage in the motor category, but as much fun as it is to ride, even the larger 2-stroke doesn't stack up evenly with 250F machines.
For those of you who want a little more edge but still want to keep all of the nimble attributes of a one-two-five, KTM offers the 144 which was specifically engineered for the AMA amateur MX Lites race class. The machines are exactly the same except for the engine which features a different cylinder, head, piston, control flap, crankshaft, centrifugal power valve, exhaust pipe, and CDI unit. The 144 has an undersquare 56 x 58.5mm bore/stroke combo compared to the 125's 54 x 54.5mm. Even with the larger displacement engine, the bike still weighs in at a claimed dry weight of 200 lbs. The 144 also has a fourteen-tooth front sprocket due to the additional power output of the 144 engine, one cog larger than the 125.
The bored and stroked 144 offers an even more versatile powerband. It has noticeably more grunt throughout the rev range and has a little more top-end hit as well which really helps the 144 keep better pace with 250cc 4-strokes.
"I drag raced my friend on his new KX250F on the back straight," claims Zalamea "It was pretty even. This bike is definitely going to be more competitive in the Lites class."
The Dutch-designed WP suspension is all new fore and aft. The 48mm adjustable fork features 11.8 inches of travel and has revised low-friction fork seals as well as improved bushing seals for better slide efficiently throughout the stroke. An updated valve stack in conjunction with a reshaped bottom stop all translate into the bikes having better bottoming resistance when the fork is at maximum load. Zalamea agreed.
"The fork had good bottoming resistance. Even when I hit bottom you could barely feel it which was confidence inspiring," explains Mr. Z.
With much attention being focused on the bottom portion of the internals our test rider had less of a positive experience with the upper range of the fork. Had we more time with the machine we are confident we could have gotten the problem sorted with a few clicks of the tool-less compression adjusters, but as it stands we were unable to completely eliminate the gremlins.
"The front fork seemed to be set up a little harsh on the top stroke," commented our 150-lb. tester. "I had a tough time settling the forks into a turn."
The real advantage of riding this duo of Katooms lies in their handling characteristics. After getting the suspension set up, these lightweight 2-cycles can go anywhere you want them to.
Handling the suspension needs of the rear wheel, the preload, high/low-speed compression and rebound adjustable WP monoshock now features an entirely aluminum body similar to the one adorning the '07 450SX-F. The trick-looking piece sports 13.2-inches of travel. The distinct linkage-less rear suspension of the KTM offers a unique ride and takes a few laps to get acquainted with its action.
"The rear end wouldn't settle in the turns the way I wanted it to (at first)," said Zalamea. "But after getting use to the rear shock's action, I started to feel comfortable putting it on its side in the corners."
What really sets KTM apart from the other manufacturers is its attention to detail and liberal use of top-of-the-line components. The suspension houses a set of gorgeously-painted black Excel wheels that are kept in check by powerful Brembo disc brakes. The binders functioned flawlessly giving the rider a tremendous amount of feel at both levers. The self-adjusting Magura hydraulic clutch keeps the motor zinging and has a ridiculously light, consistent pull at the lever. The close-ratio, six-speed transmission is silky-smooth, and has excellent gear spacing that allows the 2-stroke engine to stay on pipe with ease.
At the legendary Glen Helen raceway, the new ultra-light KTMs are entertaining to ride. Compared to the more common, bulkier Thumpers, the mountain-bike-with-an-engine feeling of these MX machines makes them an incredibly different experience. The power is snappy and the bikes accelerate swiftly as you get into the meat of the powerband. Placing either of these bikes anywhere on the track is almost effortless due to their extreme maneuverability. KTM proves once again that it has found the right combination of engineering and quality components that equate to a well-made, affordable motorcycle. MSRP on the '08 125SX is $5,498 with a $300 up-charge for the 144SX. Expect to see them at your local KTM dealer by early September-allowing you to enjoy the dog days of summer in 2-stroke style.
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