Warm weather -- and track days -- are back at last. But if your old ride's getting a bit ragged, maybe it's time to upgrade.

Here are seven ways to put some fresh scuff marks on your knee pucks:

* 2007 Suzuki SV1000S (MSRP $8,699) -- Consider it a 'Busa on a budget (with much lower insurance costs). The SV1000s is a handsome V-twin "naked" sport biked powered by a 996 cc DOHC, fuel-injected and liquid-cooled, 90-degree V-twin engine connected to a six-speed gearbox. The short stroke, big-bore engine features 11.6: compression and is designed for high torque output on the bottom end with enough power on top to tickle 150 mph. The result is a very tractable, forgiving bike that's equally at home slogging along in heavy traffic as it is running all-out on an open road. And unlike some of the bikes in this price range, the SV's front forks are fully adustable for preload, compression and rebound damping -- as is the rear monotube suspension. You also get a stainless steel exhaust system and full instrumentation that includes a low-fuel light. Seventeen-inch rims -- with a fat, 180/55-ZR series tire out back -- tie it all to the ground. This "liter bike" bike weighs in at just 410-lbs., too -- making it as "flickable" in a corner as it is comfortable to maneuver in tight city traffic. The SV1000S is available with bikini-style mini-fairing -- or "euro" style with open headlight and small wind deflector. Your choice of blue or black.

* 2007 Ducati 1098 (MSRP $14,995 ) -- The much-anticipated successor to the 999 Superbike arrives with an even larger, even more ferocious 90-degree V-twin engine belting out 160 horsepower, along with a much-revised suspension and up-rated Brembo brakes featuring race-derived monobloc calipers for 11 percent more stopping power at high speeds. The 381-lb. 1098 also marks the first OEM use of Pirelli's track-ready soft compound Diablo Corsa Pro rear tire, in a meaty new 190/55-17 size. An even more aggressive S version of the 1098 ($19,995) is available as well; it comes with twin Termignoni race canisters and recalibrated fuel mapping for the fuel-injection system. The only real "Ducati downside" is you won't find a dealership on every street corner -- and parts can be hard to get (and take time to get there). But the upside is you'll own an Italian exotic -- something else you won't find on every street corner, either.

* 2007 Yamaha YZF-R1 (MSRP $11,599 ) -- All-new for '07, the latest R1 street bike's not far removed from full-on MotoGP race bikes. It features drive-by-wire throttle control (instead of cables) and a ram-air, variable-length intake funnel system that adjust from 65 mm to 140 mm, boosting low-end torque and high-RPM power. The 998 cc DOHC in-line four features 12.7:1 compression, titanium valves and a 32-bit ECU. The '07 R1's cooling system has also been up-rated by 13 percent -- and a new liquid-cooled oil cooler has been added. A 15,000 RPM tach, shift light and lap timer are included with the gauge package. The six-speed transmission has a race-style slipper clutch to limit wheelspin during downshifts at high-speed corner entrances -- and there are six-piston, radial-mount calipers to haul you down from the 160-plus mph speeds this bike can reach. An underseat titanium exhaust and ultra-compact engine package increase cornering clearances, allowing for aggressive lean angles on the track. This is a very serious bike -- for serious riders looking for a track-ready machine that's almost unbeatable (in the right hands) on the street.

* 2007 Kawasaki Ninja ZX-14 ( MSRP $11,599 ) -- Perhaps the world's ultimate muscle sport bike, the ZX-14 one-ups the old ZZR1200 (and ZX12) by a considerable margin in every category of performance and functionality. It is, quite simply, the most powerful street bike Kawasaki has ever offered for sale to the general public -- one-upping even the former king, Suzuki's GSXR1300 Hayabusa. The ZX-14's 1352 cc DOHC inline four produces more than 170 horsepower -- enough to get you to 62 mph in 2.5 seconds, through the quarter mile in 9.83 seconds -- and from there to a top speed that's "limited" to 187 mph. This bike was designed for sustained high-speed riding on European roads, including Germany's Autobahnen -- where a bike like the ZX-14 can stretch its legs at 170-plus. Accordingly, it features a large 5.8 gallon tank, excellent wind protection and rider ergonomics (seat height, bar position, etc.), plus quad projector-beam headlights -- which are just about the only things that can outrun this machine. The ZX-14 also accepts hardbags for extended touring. Comes in Diablo Black, Candy Plasma Blue and Special Edition Pearl Crystal White. The ZX-14's a big machine -- 474 pounds at the curb -- and with so much power, it can be a handful. Approach with caution, if you haven't got a lot of seat time on very powerful open-class bikes. l

* 2007 Aprilia Tuono 1000R Factory (MSRP $16,999) -- Built around a super lightweight/high-strength twin-spar alloy frame housing a pumped-up version of Aprilia's famous 60-degree DOHC V-twin, the Tuono R Factory is more than just two-wheeled eye candy -- it's a machine built for the expert rider who wants the ultimate in naked bike aggression. The R's magnesium V-twin gets larger intake and exhaust valves, special high-flow exhaust and re-mapped, twin-throttle body EFI to produce 139 hp at 9,500 RPM -- making it one of the most potent V-twins of its type ever offered in a production bike. In a chassis that weighs less than 400 pounds, the resultant performance is nothing short of spectacular. Built as much for the track as for the street, the Tuono R's race-derived features include radial mount Brembo brakes with stainless steel braided lines and sintered metallic pads, Ohlins front and rear fully adjustable suspension -- and available options that include super-lightweight forged magnesium alloy OZ racing wheels, twin-silencer Akropovic exhaust, Ohlins steering damper, frame sliders and carbon fiber covers. The R Factory is a limited-run bike, so get your order in early. Only one color is available: Lion Red

* 2007 Honda 919 (MSRP $8,499) -- A great choice for the sport bike enthusiast who values looks and good value as much as great performance. The 919's fuel-injected DOHC in-line four isn't hidden behind plastic fairings -- so everyone can see what you're packing. Plus, if you lay the thing down, you won't be spending thousands on expensive bodywork (be sure you buy some sliders, just in case). With a compression ratio of 10.8:1, the 919 is also happy on a diet of mid-grade unleaded. The bike features a six-speed clsoe-ratio gearbox and fully adjustable front and rear suspension, with seven position preload settings for the rear mono-shock. The 919's ergos -- front rake, peg position, seat and bars -- are sporty but still comfortable enough for longer rides. The 31.3 seat height makes this a good bike for medium-sized riders, who might find other sport bikes too tall. A center stand is available, too -- a feature many sport bikes don't offer, but which makes changing tires and other basic maintenance a lot easier. The '07 919 comes in just one color -- candy red.

* Buell Firebolt XB12R (MSRP $10,495) -- A different-drummer sportbike, the Firebolt's 1203 cc air-cooled 45-degree Thunderstorm V-twin peaks at a relatively low 6,800 RPM (most high-performance liter-class sport bikes have engines that run to 10,000 RPM and beyond). But it pounds out 103 peak horsepower and with 84 lbs.-ft. of torque, the powerband's strong throughout the range -- not weak on the bottom end, with an abrupt tip-in that can get less experienced riders in trouble -- as sometimes happens with high-revving in-line four sport bikes (which are notorious for their sudden power spikes as the engine comes alive in the upper reaches of the RPM range). The XB's ample torque also allows the use of a five-speed gearbox (instead of the usual six-speed) and you'll find it's not necessary to shift as often to keep pace with changing traffic/riding conditions. Also unique to the Buell is the use of belt drive (rather than the usual chain), which cuts down on adjustment and eliminates the need to keep a chain oiled. The XB12R is available in MIdnight Black and Sunflower Yellow -- with either Cherry Bomb or Designer Black 17-inch, six-spoke rims and a Kick Ash translucent windscreen.