Better Than Ever?
Photos by Scott Hoffman
Yamaha introduced the 2017 YZ250F at Glen Helen Raceway in Southern California and DirtBikeTest was there.
The 250F received a plethora of changes–18 different changes from the previous model year with many focused on improving the already potent engine. With small changes like a 15mm shorter air funnel (or velocity stack) coming from the airbox, an aluminum throttle body joint to warm the intake tract and new intake tract within the cylinder itself, Yamaha claims an increase in in mid-to-top power.
The engine is very strong on the smaller YZ-F as it has a nice hit off the bottom. It isn’t too abrupt where it rips you off the bike but instead very manageable power that will pulls through the turns.
We felt the powerplant was as strong as ever– it keeps on pulling far into the top end as if it never ends or at least revs into the Stratosfear. The most noticeable change may have been how the rev limiter alters the over-rev and how it cuts the ignition at redline. The cuts to the ignition are more more frequent and not as apparent and it gives the bike a longer pull and does not fall as flat on top if you are a redline-type rider. Riders familiar with the 2016 will definitely notice this change as it now acts like all the other bikes in its class.
Also, an interesting change from the 2016 to the 2017 was the valve seats. Before, there was more of a sharp edge where the valve would sit but for the new model, Yamaha made it a much smoother transition which also increased the diameter by 0.4mm.
Some other internal changes that occurred on the 250F were improvements to the transmission and clutch. The shift cam features grooves in it which they supplies oil to reduce the friction. We felt shifting was improved from last year as it was very smooth and effortless, but time will tell. Also, the gears received some changes with increases in width. Lastly, the clutch actuator arm was shortened 3mm and the angle was changed for a smoother and accurate engagement.
Now the clutch pull is so easy, using the clutch to ride a gear high is simple. Boosting the power with it really works but this could spell trouble. We are worried that the clutch will be easier to really heat up and it may fade and wear quicker but this did not happen in our first day on the bike.
Updates to the frame were also part of the 2017 changes, with thicker sides near the swingarm pivot, similar to with was done on the 450f in 2016, The lower engine mounts were also altered to steel and the upper mounts shape changed. This increases the rigidity along with the more rigid outer fork tubes. Ironically the outer tubes are in fact more rigid than on the 450F outer tubes. The 17 250F outer fork leg is very similar to the 2014 fork tubes. Yamaha tested with several different tubes and found that the stiffer tubes worked better giving the bike a plusher feel with less internal binding. To compensate, Yamaha utilized 4.6 N/m fork springs over the 4.7 N/m springs from 2016. Although the Yamaha YZ-F may be wide near the airbox/intake area, most testers don’t comments about an odd feel it when riding.
Although the Yamahas look big and heavy due to the airbox intakes atop the usual tank area, most don’t feel it when riding. The 250F corners well and it stays planted in the ruts.
The suspension felt very balanced and dependable all day up and down the monstrous hills of Glen Helen and even in a second session at Milestone Raceway later in the day. Yamaha is still using the popular KYB SSS spring fork and not air like most other competitors. The SSS is a very predicable fork and plush on small bumps and feedback has always been positive. The only negative is the weight saving when using the non-spring air forks. The SSS always offers great bottoming control, even with the lighter springs for 2017, providing you are in the right weight category for a 250F.
Along with the recessed dzus fasteners and new rear disc material, the footpegs and shifter were also lowered 5mm and the shifter was made 76% stronger with the added rigidity compared to 2016. The brakes worked noticeably well and that is needed when riding the enormous hills of Glen Helen.
The YZ250F comes in 2 color ways this year: Red/White and YZ Blue. It retails for $7,699 and includes the bLU cRU benefits with various amounts of support when racing. We’ll be putting laps and motos on these bikes in the coming days to get you a full test with settings and impressions.