2008 KTM 125SX & 144SX Test <-- Bikeintro Motorcycles

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2008 KTM 125SX & 144SX Test

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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.”

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.”

source: http://www.biketestusa.com