250 TWO STROKE SHOOTOUT: YZ250 versus RM250 versus 250SX
My, how the mighty have fallen. Many years ago, an MXA 250 two-stroke shootout would have included bikes from Honda, Yamaha, Suzuki, CZ, Kawasaki, KTM, Husqvarna, Maico and Bultaco. Today, modern motocrossers only have three 250cc two-stroke choices (and one of those players has announced that 2008 is their last year in the class). Many racers have given up on two-strokes, but not the MXA wrecking crew. We grew up on them, and while we see the writing on the wall, we don’t want to go down without a fight.
As with longboard surfers, drive-in theater owners and hot rodders (especially those with rat rods), the riders of 250cc two-strokes are the last bastion of the grand old days. As the world veers towards a four-stroke future, only the hardest of the hard-core are still lashed to the mast of the SS Ring-Ding.
This is not a comparison test between two-strokes and four-strokes. Why not? Because no self-respecting two-stroke rider would ever be seen racing a thumper. The 2008 Suzuki RM250 (in its last year), Yamaha YZ250 and KTM 250SX are the last of the breed. This shootout is for two-stroke diehards only.
Q:WHAT’S NEW ON THE 2008 SUZUKI RM250?
A:Here is the list.
Q:WHAT’S NEW ON THE 2008 YAMAHA YZ250?
A:Here is the list.
(1) The fork spring has been upped from 0.42kg/mm to 0.43 kg/mm.
(2) The rear chain guide is downsized and is 83 grams lighter.
(3) Wave rotors replace the previous round rotors. They are 50 grams lighter.
(4) The fork dropouts come straight from the YZ250F. They are lighter. Additionally, the forks have a new compression valve and low-friction metal bushings.
(5) The plastic fork guards wrap around farther and weigh 130 grams less.
(6) For 2008, the YZ250 fork stanchions are 4mm shorter.
(7) The front brake caliper is borrowed from the YZ250F and saves over 300 grams.
(8) Yamaha’s front brake master cylinder has a smaller piston for more braking power. The brake lever angle is higher on the master cylinder, while the lever itself is moved 9mm outward.
(9) The total weight savings is two pounds over the 2007 YZ250.
Q:WHAT’S NEW ON THE 2008 KTM 250SX?
A:Here is the list.
(1) The engine cases have been modified to reduce the volume around the reed cage. The decrease in volume improves throttle response.
(2) The intake tract, from the reed cage to the transfer ports, has been smoothed out to improve fuel flow.
(3) The connecting rod has been lightened, while the area around the top-end rod bearing has been redesigned for more oil flow.
(4) The fork guards wrap around the fork tubes more for better roost protection.
(5) The front fender gusseting on all 2008 KTMs has been beefed up to stop the fender from wiggling.
(6) The handlebars have been changed to Renthal’s 996 bend.
(7) Fork and shock spring rates have been increased (a 6.6 kg/mm rear spring and 0.44 kg/mm fork springs).
Q:WHICH ONE HAS THE BROADEST POWERBAND?
A:Yamaha. The 2008 Yamaha YZ250 has the most usable powerband of the bunch. It comes on strong right off idle, pulls through a solid middle and never gives up (at least not until its competition is wheezing). It doesn’t make the most bottom, middle or topit just makes the right kind of power at every stop on the curve.
Q:WHICH ONE HAS THE MOST RESPONSIVE POWERBAND?
Q:HOW DO THE THREE CONTENDERS RUN?
A:If you are looking for a specific type of power, these three engines run the gamut. Here are the power profiles.
KTM 250SX. It is broad and flat. The KTM has a torquey, easy-to-ride powerband. It picks up cleanly off the bottom and pulls strongly into the middle. Then, a strange thing happens; the KTM 250SX hangs. From around 7500 rpm to 9500 rpm, the KTM?s horsepower output doesn’t change very much. It runs very flat in the meat of the powerband. Every test rider claimed that it signed off sooner than the RM and YZ. They were right, but wrong at the same time. The KTM 250SX actually revved higher than either the Suzuki or Yamaha, but when it signed off it gave up the ghost very suddenly. The power didn’t tail off gradually; it plummeted at 9500 rpm.
Suzuki RM250. It is short and punchy. The 2008 RM250 powerband is strong everywhere, but because it turns over quicker than the other two engines, the powerband feels shorter than it is. The quick rev and light flywheels make the RM250 go through its powerband in two-thirds the time of the YZ and KTM. Overall horsepower peaks at 8700 rpm and is as good or better than the KTM or YZ’s peak numbers.
Yamaha YZ250. It is torquey and effective. Yamaha’s take on two-stroke power is almost four-stroke-ish. It delivers its power with a hooked-up, tractable, broad and metered power output. It gets the job done by putting every ounce of power it makes into the ground. It has the most impressive powerband of any of the 2008 250s. This is the best engine in the class.
Q:HOW WOULD WE RATE THE THREE POWERBANDS?
A:Yamaha first, Suzuki second and KTM third.
Q:WHICH BIKE HAS THE BEST FORKS?
A:Yamaha. The YZ250’s Kayaba SSS forks are helped immensely by their stiffer fork springs, but they would have won this category even if they were softer. Suzuki’s Showa forks are second, but they require some wild compression and rebound clicks to get into the ballpark. KTM’s WP forks are third. They have a significant amount of mid-stroke harshness, which can be ironed out by lowering the stock fork oil height.
Q:WHICH BIKE HAS THE BEST SHOCK?
A:Yamaha has their numbers dialed in. Suzuki is close with its Showa shock. KTM is third, but vastly improved over 2007 thanks to the stiffer shock spring.
Q:WHICH BIKE HAS THE BEST BRAKES?
A:KTM. No contest. KTM’s front brake is incredible. However, most test riders prefer the adjustability of the Yamaha rear brake over the KTM’s. Suzuki’s rear brake is touchy to adjust. If you get it slightly wrong, it will overheat and lock up.
Q:WHICH BIKE HAS THE BEST GEARBOX?
A:Yamaha. The YZ250’s gear ratios are spot on, and the bike will shift under full power. The KTM is better than the Suzuki, which has a gap between second a third and a very light touch at the lever. Too light. Additionally, the Suzuki resists going into neutral.
Q:WHICH BIKE HAS THE BEST GEARING?
A:We added one tooth to the rear sprockets of all three bikes.
Q:WHICH BIKE HAS THE BEST CLUTCH?
A:KTM. Every brand should switch to a hydraulic clutch. Although the feel takes some time to get used to, it doesn’t need adjusting and self-regulates. The Yamaha is second and the Suzuki is a very distant third.
Q:WHICH BIKE HAS THE BEST HANDLEBARS?
A: A push. Both the Renthal Fat Bars (Suzuki and KTM) and ProTaper bars (Yamaha) are very good.
Q:WHICH BIKE HAS THE BEST TIRES?
A:It all comes down to terrain, but we rate them as Yamaha first, KTM second and Suzuki third.
Yamaha: We aren’t big fans of the Dunlop 742FA front tire, but love the 756 rear tire.
KTM: Somehow KTM got its hands on a set of old-school Bridgestone M59/M70 tires. We like the M59 front for intermediate dirt, but thought the M70 had been discontinued years ago.
Suzuki: The 2008 RM250 is spec’ed with Bridgestone 401/402 tires. There are many better tires on the market than these. The rear is passable, but the front is worse than the Dunlop 742FA.
Q:WHICH BIKE HANDLES THE BEST?
A:The Suzuki. The RM250 has pizzazz. It’s ultra quick, very agile and amazingly responsive. The RM250 steers on a razor edge, but is very touchy to get set up. If you miss on the fork height, rear sag or tire pressure, it can become overly sensitive to input.
The KTM 250SX’s handling was a surprise. Gone are the days of the slack Austrian bikes with the big push in the front and tons of understeer. It was crisp.
We have always liked the YZ250’s middle-of-the-road handling. Not because it is great, but because it is tabula rasa. You can make it do what you want, but it won’t do it without input. It’s predictable, which is neither a compliment nor a criticism.
Q:WHAT IS EACH BIKE ALL ABOUT?
Here is a quick thumbnail sketch of what we really think about the last three 250 two-strokes.
Suzuki RM250: The RM250 is a light, wispy and agile machine. It favors riders who want to play gun-and-run. It is a Supercross bike. The engine and suspension are good, but not awesome. This bike is all about handling.
Yamaha YZ250: The YZ250 is all about its tractor powerband. It is a mistake-free engine. It can be run at quarter-throttle, half-throttle or full-throttle. No terrain fazes this engine. It’s a stupendous engine mated to the best suspension. The handling is a little stodgy.
KTM 250SX: KTM can never get the mix right. Some model years they have incredible engines in albatross frames, and other times it is vice versa. For 2008, they have a very good frame, superlative brakes and a weirdly configured powerband.
Q:AND THE 2008 250 TWO-STROKE WINNER IS…
A:In the opinion of the MXA wrecking crew, the Yamaha YZ250 offers the best all-around package for a rider looking to stick with a two-stroke.