The Ultimate Motocross Bike

The 450
OK, so all you conspiracy-theory guys are right. Two-stroke 250s smoke 450s, but the factories want to sell more parts. And, yep, none of those factory teams or top riders tested back-to-back; they just switched to 450s because they had to. Are we square now? Fine.

Now that those guys are satisfied, let's look at some facts. For riders at a National level there's no way to compete equally on a 250cc two-stroke against modern 450 motocrossers. The actual weight difference is small-the lightest bike here is 228 with a full tank and the Yamaha tips the scales at 239. But a 450 makes more and smoother power over a longer rpm range, seemingly getting the power to the ground more effectively. The YZ is definitely strong here, and adding the Akrapovic pipe certainly helped it out. Current 450s are easy to start, handle well and have the absolute latest in suspension and chassis technology. They are basic to get starts on, effortless to learn new jump sections with and are usually easy to care for. Any local guy should get a year of hard racing without looking in the engine, and weekend warriors perhaps much longer.

If you thrash the clutch, hammer the rev-limiter or let the bike ingest dirty air, like any four-stroke, you will have expensive problems. Sure some guys have had unusual, catastrophic failures and the resulting repair bills can give Bill Gates indigestion, but most dirt riders ride these things for many trouble-free hours. When things do wear, it's usually the valve train, and incomplete repairs or lack of checkups add to the bikes' poor reputation.

In all of our empirical, measured tests the 450 pretty much came out on top. It didn't matter whether the track was tight or fast, rough or smooth or what level the rider was at. The 450 topped the roll-on, the full-throttle drag race, tied or was fastest for almost every rider's lap times and was out front on nearly all the starts.

If you want every advantage when you're racing, you want a 450. There is a dark side. A 450 is hard to hold onto and gets harder as a track grows rougher or more technical. It chews through tires and chains, and it just plain feels heavier and harder to throw around in turns and in the air. Despite what you saw RC do for years, if you're small or light, a 450 can be more than you bargained for as well as genuinely difficult to get the suspension dialed. A bike this fast demands absolute throttle control, and when you're tired, that level of control is elusive.

It is insane how good 450s...        read full caption It is insane how good 450s are. Powerful beyond belief, light weight and amazingly ridable.

Kris Keefer

For throwing down the fast...        read full caption For throwing down the fast lap times, it's hard to beat a 450...but it is possible.

Jimmy Lewis Rule changes... 

   

  read full caption

Jimmy Lewis
Rule changes put 250 two- and four-strokes head-to-head in amateur racing. MX just got more interesting.

Choices
Does this mean that a 450 is the bike for every rider? No, just as close as it gets at the moment. But that doesn't mean it's the correct bike for all riders and certainly doesn't guarantee it being the most fun or effective for your conditions and riding style. Mixing 250 two-strokes and 250F four-strokes in amateur racing has revitalized mixing gas. And increased sound regulations has helped the popularity of two-strokes surge in Europe. If you like to ride wild and loose, you have no business on a bike that is 450 fast (or 250 two-stroke fast, for that matter) unless you have buckets of skill and experience. Is your joy of motocross in railing ruts and flinging the bike around? Are you a bit sloppy with throttle control? Same answer. Imagine an international "NO" symbol across all 450s. Don't want to work on your bike much? You're right, two-strokes are better. The great thing about modern motocross is having amazing choices. The lap times prove all these bikes are viable, fun and winning choices. But on average, a 450cc four-stroke is the big dog on the track. So this settles the bike question. Whether you want to follow the crowd of big dogs is a question you'll have to answer for yourself.

For some of the straight-up opinions, more photos and dirt on the bikes, check out www.dirtrider.com.

Weight (ready to ride, tank full)
CRF250R: 228 lb
KTM 250 SX: 230 lb
KX290F: 230 lb
YZ450F: 238 lb