Spring Creek Motocross plays host to the Millville Outdoor National each year; a venue capable of thrashing the best MX bikes and riders in the world. Kawasaki used the famous racetrack as the introductory proving grounds for its new 2013 KX250F. MotoUSA made the trip to Minnesota and laid ruts in the sandy loam for two full days of riding on Kawasaki’s latest bid for 250F moto dominance. After watching a detailed presentation on the new model changes, getting the skinny from factory technicians and riding until our bodies ached, it’s clear that green and black machines are going to be fighting for race podiums across the country.
DESIGNED BY
FAISAL DAYO
Extracting the most performance from an engine requires efficient combustion, and that starts with getting the proper air/fuel mixture delivered into the cylinder. Kawasaki introduced a second injector in its Digital Fuel Injection (DFI) system a year ago. The second injector is located higher (upstream) on the intake tract, and squirts atomized fuel prior to the main injector. Both are four-hole designs but the upstream injector has been repositioned for better fuel delivery. Bigger news, however, is the intake tract itself, which has been reworked to allow for a higher and more direct shot into the combustion chamber. The intake duct is straighter and feeds into a reshaped cylinder head intake. The combination creates a downdraft system that minimizes the bend located right before the intake valve that was present in the 2012 model, thus shooting the good stuff into the cylinder more effectively. The intake valve seats are 4% more dense and the intake cam timing has been retarded by four degrees. Kawi credits these changes with better high-rpm performance and longer durability.
For a more explosive bottom end, Kawasaki boosted the compression ratio to 13.8:1 (vs. 13.5:1). This was accomplished by shortening the cylinder minutely (36.2mm vs. 36.3mm). Engineers also targeted a longer-running motorcycle by changing up the piston skirt in high-pressure areas, and installing a new spark plug cap to help keep out water and mud. The ignition rotor is heavier to help make the power delivery more tractable.
A new exhaust system is part of the engine package that makes
the KX250F a serious ripper. Kawi also provides three different
ignition mapping couplers for quick engine tuning.
“The thing is a rocket ship,” says test rider Frankie Garcia after ripping around Spring Creek MX. “Even better, it doesn’t stand out in one particular area. It has all this bottom-end power and the power just keeps growing all the way until it tops out and hits the rev limiter. It’s insane!”
One of several designs carried over from the 450 is the addition of interchangeable ignition mapping couplers. The bike comes with a trio: stock (green), hard-terrain (black) and soft-terrain (white). The hard terrain mapping smoothes power for more traction and the soft-terrain option makes for a more aggressive hit. We sampled all three on Millville’s varied terrain and could feel a noticeable difference. The stock option is a terrific blend of the two, but both of our testers preferred the black coupler despite a deep ripping during track prep, plenty of water and naturally soft soil around most of the circuit. It has just as much power on tap as the others but is easier to control on corner exits. Our non-pro tester also claims more control while navigating ruts with the smoother, more tractable output.
This is an incredible tool for a racer who faces certain conditions in the morning and then a totally different track in the afternoon. Before the ability to electronically control the fuel system this would have been an expensive and massive chore of swapping exhaust pipes. It’s like Kawi gives the rider three full-system exhausts that you can toss in the toolbox. Changing a coupler takes about 10 seconds. It is located on the throttle side of the steering head and requires no tools. The bike must be shut off completely and restarted, however, or else the altered mapping will not be recognized by the ECU. In addition to the preset couplers, Kawi riders can also use the accessory FI Calibration Kit to create their own custom maps.
A 4mm thinner chassis is also more rigid, which
makes for a sharp turning and stable machine.
The steering head and shock tower are stiffer and the upper engine mount is reshaped, though mostly to provide better access to the idle speed adjuster (which is now knurled for easier grip). Lengthening the front portion of the aluminum swingarm by 20mm offers a claimed 4.2% increase in rigidity. Also, the lower triple clamp pinch bolts are located on the side instead of the front which gives the front end less flex.
Kawasaki still employs the Separate Function Fork on its 250F, despite the 450 getting the fancy pneumatic system. That’s fine with us because the front suspension is great. The right fork contains the spring and offers preload adjustability – something we torqued on in conjunction with shock preload for a perfectly tailored ride height. The left leg holds compression and rebound settings. Internally the main piston (rebound) and sub piston (compression) are both larger which stemmed from increasing the lower fork tube from 47mm to 48mm. Damping circuits on the fork and shock have been tweaked for the updated chassis.
One test rider was able to hop on and go virtually all day with only a couple clicks. Our other rider chased the balance setup considerably but was able to finally lock in settings for the final few sessions after toying with nearly every adjustment front and rear. It highlights one of the Kawasaki’s greatest strengths – tunability. Not only are the components good – fork, shock, chassis and tires – but they can be tweaked in so many ways that it’s basically the rider’s fault if they can’t find something pretty darn suitable. Both of our riders were very happy with the end result, noting the updated Showas as an improvement over previous KX-Fs.
“The shock impresses me even more than the fork,” says Garcia. “I never encountered any bucking or swapping. In the corners the shock really stood out when packed hard into a rut where the bike planted extremely well. That, along with the added rigidity, gave a lot of confidence. The front end is really planted also except when hitting sharp-edged braking bumps,” he continues. “That’s when the front got a little knifey and twitchy at times, but it was never a huge issue, especially for stock suspension.”
Revised suspension and upgraded brakes are
capable of handling everything the Millville
track can throw at them.
Though one finger stays on the lever, the rest of the hands make use of new grips. We can’t feel much of a difference in terms of comfort or durability, but they are each 10mm longer and Kawasaki claims they’ll actually come off when it’s time to replace them. The grips are just the tip of a complete styling redesign and ergonomic adjustments. A flatter seat profile helps the rider move around during cornering. Combined with the thinner chassis, this helps give the bike a very light and manageable feel on the ground or in the air.
“Through rough sections and the Millville whoops, the bike is easy to grip,” says Garcia. “The 4mm change is very easy to identify. It helps with gripping the bike and also made it more comfortable and easier to maneuver.”
Two days on an immaculate Millville track would be great by
any standard, but aboard the 2013 KX250F it was pure MX bliss.
“The all-new styling is spot on with a modern look,” says Garcia who couldn’t stop gushing over the front end. “When I laid eyes on the new bike, I immediately fell in love with it. The thing just flat out looks badass!”
What else would we like to see? Not much, but how about snagging those adjustable footpegs from the 450 as well? With so many revisions for 2013 the new model feels like a refined, solid package. Not only does Kawasaki offer top-level performance all around, but the KX250F has more adjustability than any other bike in the class. This is a bike that’s capable of working well for a wide variety of racers, and it’s going to be one heck of a platform for Mitch Payton and the Pro Circuit racing team in the coming year.
Hello mini moto junkies, and welcome back for Phase 2 of our Honda CRF150R Expert project bike. In case you missed it, we did a full review of the new for 2012 Honda mini thumper a few months back and came away very impressed with the changes Honda has made to the 150R. Although the bike was very good in stock trim, we couldn’t help wanting to make it even better and have since been embellishing the little ripper with some of the coolest aftermarket products available.
USA
DIRT BIKES
With the bike controls up to par, we are now ready to focus on the bike’s drive components and getting the power to the ground. Most of the components in this phase are high-wear items that needed to be replaced after a couple months of testing anyway, but also benefit the performance of the bike and are a definite improvement over the stock parts.
Kenda K775 Washougal Intermediate Front Tire
Kenda K775 Washougal Intermediate Rear Tire
$74.95 - Rear
$76.95 - Front
The Kenda Washougal tires provide great traction in corners,
particularly the front tire. The set has excellent wear resistance.
Residing in the Northwest, we couldn’t help but try out a tire named after one of our favorite tracks. Washougal is well known for its tricky, and ever-changing dirt. A morning practice session starts off with deep loam, and often mud, but by afternoon the track dries out and packs down into a very hard and slippery surface. Since we were testing at a wide variety of tracks that range from sand to hard-pack, the K775 sounded like the perfect choice.
After a couple months of use, we came away very impressed with this intermediate terrain tire. We found that the Kenda K775 Washougal Intermediate front tire and Kenda K775 Washougal Intermediate rear tire hook up extremely well in the soft terrain, whether its sand or mud, yet still performs well on hard pack. Our mini test pilot reports increased grip, especially from the front, which has really inspired a lot more confidence in the corners. Most impressive, for the cost-conscious racer, is the long life of the tires. We have logged extensive hours on the Kendas and they show very minimal wear.
ProTaper 420 Rear Sprocket
$64.95
Stock gearing on our 150 Expert was a little tall for most of the tracks we were riding and could be improved by adding a tooth to the rear. Since the stock steel sprocket was starting to show some wear, we opted to replace it with a ProTaper aluminum sprocket. The added tooth made our little CRF a little quicker out of the corners and still has plenty gearing left up top for those high-speed sections.
The ProTaper rear sprocket is CNC machined from 7075-T6 heat-treated aluminum and shaves serious weight compared to the steel cog it replaces. ProTaper claims its proprietary mud groove design results in 44% more tooth surface area which increases the life of the sprocket dramatically. It appears the sprocket is living up to this claim as our sprocket is showing very little wear after months of use. ProTaper offers the sprockets in either a black or magnesium anodized finish.
Going up one tooth in the rear helped get our CRF better drive off the corner, but it still has enough top-end to handle high-speed sections. The ProTaper gold chain looks great and a Hammerhead case saver protects without clogging with mud.
ProTaper 420MX Chain
$34.95
With a new, bigger sprocket needed in the rear and our stock chain stretched out quite a bit, upgrading the drive chain was a no-brainer. We opted to stick with ProTaper to maximize compatibility by purchasing their 420MX gold series chain. The gold series chain is very lightweight, but also maintains a 5000-pound tensile strength due to its premium chromoly construction. While you can improve chain life with an O-ring chain, we opted to stick with the traditional to reduce drag and keep our little CRF producing as many ponies as possible. Our ProTaper chain stretched out a bit at first, but has now settled in and very rarely needs adjusting.
ProTaper 420 Front Countershaft Sprocket
$25.95
While we didn’t require any gearing change up front, it’s always a good idea to use a new sprocket when replacing the chain. Again, to keep things consistent, we again chose ProTaper in the stock 15T size. While there is not a lot of difference in countershaft sprockets, ProTaper does use drilled holes to keep the weight down, and like the rear, utilizes self-cleaning mud groves to prevent dirt build-up. Also, ProTaper claims a special coating over the cro-moly steel helps retain strength and adds life.
One of our test tracks was Racetown 395, which has a nice mix
of fast sections, big jumps and excellent dirt.
Hammerhead Designs, Inc. Case Saver
$34.95
After installing a new chain and sprockets, the last thing you want to do is compromise the life of your new purchase. Conditions can get pretty wet up here in the Northwest and the stock countershaft guard easily packs full of mud, causing a lot of unwanted wear on the chain. Simply removing the stock case guard would eliminate the potential for packing in mud, but leaves the case extremely vulnerable should you ever throw a chain.
To solve this problem we opted to install a Hammerhead Designs case saver. The case guard is CNC’d from 6061-T6 billet aluminum and provides an extremely light, yet very strong guard just in front of the countershaft sprocket. The Hammerhead guard is designed only to protect the engine case, exposing the countershaft sprocket completely by eliminating any type of side coverage. This is great for eliminating mud build up, but be careful to keep your fingers away from this area when the bike is running, as you are now vulnerable to loosing a digit if your fingers ever get too close. The Hammerhead Case Saver is extremely easy to install, and for our Honda, was available in anodized red.
CV4 Radiator Hose Kits
$86.99
Our final upgrade for phase two was a CV4 Radiator Hose Kit. With a wide assortment of colors, the CV4 kit definitely adds some cool factor to your ride, but at the same time, they also provide some performance improvements. The CV4 hoses are constructed of pure silicone with polyester reinforcement. They are able to withstand temperatures up to 420 degrees and unlike OEM hoses, they resist U.V. deterioration. They also utilize a smoother inside diameter, which allows for increased coolant flow.
The CV4 hoses come in enough colors to match any bike and they eliminate the Y connectors on some models. We found installation to be simple and the length and bends of our CV4 hoses matched up perfectly with the stock hoses.
The CRF150R Expert has become an excellent race machine and will help ease the jump to the bigger 4-stroke bikes.
Conclusion
That wraps up the upgrades for Phase 2 of our CRF150R project bike. The high-wear parts we focused on for this stage are now fresh and ready for more testing abuse. Our little CRF continues to run flawlessly and we have yet to experience any mechanical trouble. The 150R Expert is a competent race bike that has been a blast to ride. It also helps get our young rider familiar with the power characteristics of a 4-stroke. He’ll be jumping to the 250F class eventually and the Honda has been a good way to introduce the Thumper breed. Now that the weather is turning around and the CRF is better than ever, we’ll be out pounding even more laps.
For more information or to purchase these products, or other parts and accessories for the 2012 Honda CRF150R Expert, visit Motorcycle-Superstore.com.
