2011 KTM 250 SX-F and 450 SX-F First Rides - Dirt Rider Magazine

Now that you've heard all about the 2011 350 SX-F and the two-stroke line of SX models from KTM, how about a little love for the 250 SX-F and 450 SX-F. After settling down from our one-day moto session, here are our first ride impressions on the traditional MX class models.2011 KTM 250 SX-F New Features:

- New Chromoly Steel Frame

- New Swingarm (one-piece cast aluminum)

- New WP Rear Shock and Linkage

- New Fork Settings in 48mm WP fork

- New Wheels

- New Bodywork

- New Cooling System hose routing

- New Fuel Tank (1.98 gal.) with compact fuel pump

- New Muffler with bigger outlet diameter

- New Camshafts, Valve Timing

- New Exhaust Header

- New Ignition System to power fuel injection and to handle the optional electric starter components

- Engine Management System by Keihin with electronic fuel injection and a 42mm throttle body.

- Optional KTM PowerPart Map select switch allows instant selection of standard, aggressive and soft pre-programmed EFI settings.

- Optional KTM PowerPart user setting tool will allow data logging via laptop and the opportunity to change EFI mapping with a few mouse clicks on a laptop.2011 KTM 250 SX-F Breakdown

We've always loved the massive power on tap with the KTM 250 SX-F. But designers at KTM wanted to fill in the bottom end and mid power for 2011 as they built in the ultra-responsiveness of the EFI system. The power combination seems to be working with a more peppy punch coming from the 250F. The power still holds its top-of-the-line controllability and fun top-end pull but thanks to EFI, the responsiveness is now a form of brainless fun.

The new chassis shared across the SX-F line is nice on the 250F. The bike feels a little lighter while still staying planted and the new linkage-equipped shock seems to be settling in nicely. The bike corners like a dream. It settles quickly and keeps its attitude in check through the turns. We'll get a real test of the suspension and chassis when we get our test bike here at DR HQ. But for now, we're feeling confident this 250F has definitely improved.Compared to the 350 SX-F (because we know you'll ask) the 250 SX-F feels much softer on bottom and across the rpm spread. The bike responds more to clutching than the 350 SX-F and wakes up when given a flick of the lever. Plus, the bike still revs out great. It screams where the 350 roars, no doubt a 250-class top-end leader, for sure.We're looking forward to slapping on an e-start for giggles and its cool the KTM PowerParts catalog will be offering this reportedly simple bolt-on. Look for approximately 4 pounds of weight gain if you go e-start.2011 KTM 450 SX-F New Features:

- New Chromoly Steel Frame

- New Swingarm (one piece cast aluminum)

- New WP Rear Shock and Linkage

- New Fork Settings in 48mm WP fork

- New Wheels

- New Bodywork

- New Cooling System hose routing

- New Fuel Tank (1.98 gal.)

- New Muffler with bigger outlet diameter

2011 KTM 450 SX-F Breakdown:

The new KTM 450 SX-F is the least changed in the company's motocross lineup. Consider that's taking into account an entirely new frame, rear suspension system and airbox/bodywork and the scale of KTM's 2011 new models really comes into focus. It's no doubt the 2010 450 SX-F was the best KTM 450 MX bike ever. Its power was close to perfect and the suspension and chassis found the magic spot of plush and controlled with insane cornering. For 2011 this seems to continue.The 2011 450 SX-F remains firmly planted on the ground with great front and rear traction and easily one of the most enjoyable power deliveries in MX. The 2011 powerplant retains all of 2010's pleasantries with more refined carburetion and spot-on delivery. It comes on so strong and smooth it's almost magic. There is plenty of ferociousness in the mid if you want to snap the throttle to that range but why would you when you can drag the bike through lower rpm with beaucoup surge. All of this power and control only helps the bike corner in control.

For some, the carburetor on the 450 will come as a surprise. As every other 450 MX bike is now fuel injected, it seems out of place that KTM sticks to jets. According to KTM, there were a few main reasons to stick with the carb. One big one was cost. The addition of EFI on this bike will bump up the price. Another is weight. KTM hates adding weight to bikes unless it's worth it in improved performance. Lastly is performance. Apparently, every tester in KTM's camp preferred the power delivery of the carbureted bike. Guess what that means: the 450 SX-F has a carburetor for 2011 but there is at least one in the testing fleet that has EFI so the transition can't be too far off. We'd guess the 450 will get a major motor update soon with EFI included.The linkage shock system on the 450 seems to only help the calmness of the ride and should make track-to-track changes less drastic. KTM's have always been highly sensitive to ride-height, fork height, etc. The linkage may give them more middle ground for a range of settings to work across different tracks.

Compared to the 350 (I know, I know, everyone wants to know) we'd say the 450 easily dominates in the lug-and-chug category as it does in outright power. Where the 350 SX-F can dip into low rpm around turns and still recover quickly, the 450 can rocket away at any time below even 7,000 rpm. The 350's edge seems to be on top where it not only pulls just as hard but also feels lighter, more planted and seems to get better traction.That's about it. Now go wait patiently at your dealer until they get their bikes in stock. And don't forget to check back here for full tests of the bikes when we get them in our shop full-time.