Catching Up Or Staying Ahead?
By David Moorhead with Jimmy Lewis Photos By Jimmy Lewis and Chris Barrett
The 2019 Yamaha YZ250F is reacting to the trends and setting a few itself. Power in the 250cc four-stroke market is always paramount but the delivery has been getting more aggressive and top-end focused from the competition. Yamaha made numerous changes to the ’19 YZ250F, enough that we’ll call it an all-new machine. In 2018, the guys in Blue redesigned the YZ450F and this is where a lot of the proven changes came from. In fact, the YZ450F and the YZ250F share the same chassis except for suspension settings/springs, some electronics and motor mounts. With this platform comes the YZ250F chassis which aims to improve the overall feel. The aluminum bi-lateral beam frame is designed to increase stability, improve traction and cornering. In addition to the frame, the internals of the KYB suspension package and the fork lugs have all been changed to increase the front end feel. As for the power department, Yamaha wanted to increase the mid to top end performance without sacrificing it’s well-known bottom end torque. To gain the power curve the YZ250F was looking for, Yamaha reconfigured the cylinder head with a new valve train, more aggressive intake camshaft, higher-compression piston, and new Mikuni throttle body FI. After nailing all that, they decided to throw the icing on the cake, they went with and an electric start as well as the Yamaha power tuner app. That’s right, tune the YZ250F right from your phone.
The 2019 YZ250F definitely looks different and acts different! With the all new frame and suspension updates the YZ250F is both nimble and stable. We did a one-day riding impression at Cahuilla Creek MX. With some wide open sections, tricky tight corners and descent size jumps, as well as being at elevation, the track gave us a great feel for the bike.
Right from the beginning you can tell the YZ is very well balanced and stable. It seemed to lose the comparably harsh feeling in the braking bumps compared to the 2018 model Yamaha had on hand for back-to-back impressions. Instead, the 2019 felt very plush and gave you a feeling of increased confidence. No matter how tight the inside line is or how loamy the berm was the YZ was able to dive inside or rail the outside, the sign of a very ballanced chassis. The front end seemed to go wherever you pointed it without hesitation which made cornering no problem. And a note about the Bridgestone tires, the Battlecross X20, really shine on this bike and transition well when going from soft dirt onto hard sections especially on the turn-in.
Some of the downhills and sweeping corners developed some braking bumps but that did not seem to be an issue for the KYB SSS suspension, as we were able to power through all of the chop. The suspension and frame seemed to compliment each other around the track even as we got to some of the bigger jumps. Bottoming was not an issue and our riders were definitely on the larger range of the intended weight zone pushing the 190 lb. zone. Overall, the changes to the frame and suspension were a step in the right direction. Nothing drastic but easily noticeable because it was coming from a very solid platform to begin with.
The bike is now thinner and has been narrowed in all the right places. It has an adjustable bar position and the levers and controls all felt right at home. The lack of a kickstarter did not bother us one bit but the YZ does something interesting here. It starts right up most of the time, hot or cold. But if there is significant drag (bike in gear, dragging clutch) the battery has an overload sensor that will give it a break if you overload the battery causing a few second delay on getting the starter to spin. In a rush on the track following a tip-over, we had it happen and were able to re-create it in the pits. Something to know if you wonder why cranking isn’t instant when you push the button.
Some of the big talking points of the Yamaha design, reversed cylinder head, under-seat gas tank, forward mounted air filter are now accepted and even considered a bit normal, because they are working for Yamaha. Some of them are even a big advantage, especially in the smaller 250cc class. Also of note is that some of the changes will allow racers looking for more power specifically to modify the bikes to higher levels without some of the additional costs usually associated with getting that power.
The YZ250F received a number of changes to the engine and it was very noticeable. The 2018 had a very strong motor but seemed to fall off after mid range compared to some of the competition. With all the changes Yamaha made to the 2019 YZ250F we were able to pull 2nd, 3rd, and 4th gear a lot longer than in previous years. Even though we were at an elevation disadvantage and our test riders were a little on the bigger side for a 250F, the motor seemed to be able to pull us up the uphills and around the loamy sandy berms with ease. Now we know that an electric start is nothing new in the current mx bikes, but having electric start, the Yamaha tuner app and a map switch the YZ is more than a modern MX bike. The ability that the tuner app gave us is comparable to swapping exhaust, changing cams, jetting and even more types of tuning that took wrenches and money previously. New and done right, the YZ has a simple and visible handlebar-mounted button that takes an easy push to change the internally stored maps on the fly. Having the capability of changing maps, programmable with the yamaha tuner app, was an awesome feature for us. It was a very noticeable change from the standard stock map to a hard hitting map, one included in the app from Yamaha.
For me changing from the stock map to a hard hitting map the bike seemed to love 3rd and 4th gear. We also had one of the techs install the “SV” map. It altered the power delivery even more in a direction that livened up from the bottom end all the way through to the top end. Here some riders liked the increased throttle response but some still preferred stock where the bike was less likely to spin the wheel. But no matter what the motor seemed to have that torque everyone seeks for in a 250F while freeing up the top end pull and getting more power up there too. The simplistic ease of sending the map to the bike through a phone app and being able to compare on the fly, on track is brilliant and well executed by Yamaha on this bike. 
Of note the YZ250F has a different rev cut feeling where there is a sort of soft cut before a full rev limiter comes in. Some like this and for others the jury is still out, as it feels different. The reason is that Yamaha employs some fuel delivery changes as well as a unique ignition cut out as the bike passes 13,300 RPM then again alters that at 13,500. Of course by then the engine is past peak horsepower and just trying to stop riders from getting into the dangers of over rev. Off the bike you can hear the tone change and sound. How much more power is there? Yamaha claims they saw a 1-2 peak HP increase on the dyno and we easily believe them. Some testers felt that there was not as much in the low end but often an increased in top power makes similar low-end power feel lessened. Overall, the upgrades to the engine were a very noticeable improvement from previous years, likely more than even the chassis.
All in all, the 2019 YZ250F has made some very positive changes from handling characteristics to the ever important power curves. We can’t wait to take this bike out to a few more tracks and get some more seat time, especially playing with the tuner app which we really like.
For more info and specs visit: https://www.yamahamotorsports.com/motocross/models/yz250f
