2018 Kawasaki KX250F
When a manufacturer drops a all-new or heavily updated model, it's rare to see a large list of upgrades the following year. However, Kawasaki has broken this cycle a bit by dropping another round of updates for 2018 after a big overhaul in 2017. Up on deck are changes to the parts we saw new last year, such as the top-end of the engine. The 2018 model has a revised cylinder head intake port, mostly focused on the bridge area between the ports, along with an update to the angle of the injector in the throttle body. This injector now sprays the fuel into the incoming air stream at a straighter angle, meaning the air helps sheer the fuel to create better atomization. Speaking of fuel, the '18 KX250F also has a higher pressure fuel pump to aid the twin injected system the KX features. Beyond this, the air boot angle and length of the velocity stack has also changed. Then, once it all makes it into the cylinder head, the intake cam has been changed with two degrees more advance. Ignition timing has changed of course and the exhaust pipe as well. Everything here has been done to maximize how the air and fuel get into the engine and how it gets out. Overall there's noticeable gains across the whole range, but mostly bottom-to-mid performance, exactly what it needs to compete with the KTM/Husky and the Yamaha when it comes Shootout time.
As for the suspension, Kawasaki took back the stiffer fork spring in the SFF type 2 Showa fork and returned to the rate used in 2016....going from 9.8nm to 9.4nm. This brought back some of the plushness that the '17 model was lacking but to make up for the lack of holdup, a new valve spec was introduced, which features a check valve. This was done to gain a bit more speed sensitivity, which the SFF fork really needed to give the KX250F a wider range of damping capability. Last year's fork featured plenty of bottoming resistance, but we were left chasing the initial comfort. These forks just seem to be a bit sensitive to spring rate, as going to high shows the imbalance of the system. Overall, going softer on the spring rate brings the bike back into the realm of the target 250 rider and the large damping components on the other side can take a few clicks to stiffen it for faster/heavier riders. Out back, the shock received some internal updates and seems to be a bit more active than the previous year. Meaning it has a bit more recovery action on acceleration chop, giving better rear-end traction and taking away some of the "packing" feel from before.
All-in-all, these changes were what the Kawasaki needs to bridge the gap from the back of the pack, to the front that's being led by the Yamaha and Austrian twins. The 250F class really is competitive right now and it's going to take constant improvement to stay up front with the aggression all the manufacturers are showing in this category.