YZ250F/FX GYTR Ported Cylinder Head

What it is

• Complete cylinder head kit incuding valves and cams.
• CNC ported cylinder head.

Yamaha has one of the more impressive in-house accessory brands in the form of GYTR, Genuine Yamaha Technology Racing. Covering just about every aspect of the motorcycle, GYTR has parts and pieces for standard replacement and wear items to high performance accessories. For Yamaha’s four-stroke models and the YZ250FX in particular, a Ported Cylinder Head Assembly is available complete with a CNC ported cylinder head, a GYTR High Performance Camshaft Kit, and the stock valve train. It’s a straight plug-and-play upgrade that simply bolts onto the stock cylinder. 

The CNC porting is claimed to be more precise and consistent than hand porting and has been both dyno and track tested for performance and durability standards.

How it works

• Added torque down low.
• More pulling power up top with better overrev.
• Pulls wide-ratio transmission easier.

We’re going to get straight to the point here. Is the Yamaha 250F faster with the GYTR High Performance Head than it is without it? Plain and simple, the answer is yes. 

We tested the GYTR equipped YZ250FX back-to-back with a nearly identical stock bike in a myriad of ways to test speed and pulling power at all levels. In every situation, even when we put the GYTR bike at a disadvantage with a 30lb heavier pilot, the GYTR package prevailed. Third gear roll ons, drag races, and back-to-back motos all led us to the results of the GYTR motor having more torque and power in every area. 

Yamaha’s 250F motors are known to be stronger down low than up on top. This has been the case since the reverse engine design debuted in 2014, though they have worked on bridging that gap through engine refinements over the years. Still, the Yamaha isn’t quite up to par with some of its other rev happy competitors mostly on feel in comparison to the low end. Meaning you don’t feel the surge in power because it doesn’t surge, it continues. Putting the GYTR Head in place added a bit more surge in the top end performance, giving it more pulling power and letting it rev out while still pulling quite a bit further than ever before. 

Stock power is on the shorter side in that it doesn’t rev out super quick, but it doesn’t make the most power when it is revved. Pair that with a wide ratio transmission and it can be difficult to keep the bike in the meat of the power when you’re trying to get the most out of it. The gaps from 2-5 are on the longer side, per usual with wide ratio transmissions, and in order to maintain optimal power output, we needed to rev the bike a little further than where the power started signing off. Now, the engine character pulls easier and quicker with the wider gear ratios. 

To boot, the GYTR package also adds some torque and power down low to pull through lower RPMs and get back into the power quicker and more efficiently. Previously, rolling third gear in corners was a little tricky as it didn’t always quite have the juice, but second gear was almost too low. We now find ourselves using third gear a lot more a la like riding a 450. We like to think of us now having two gears for nearly every scenario whereas before we really only had one gear most of the time. This is the nature of wide ratio transmissions and why we don’t always prefer them, but this GYTR package gives us the benefits of having a wide ratio tranny without the drawbacks. 

In a sense, you can be much more lazy on both ends of the power and still carry good speed. You can roll taller gears through corners and tighter terrain and have the oomf to get through it without the bike falling on its face or any clutch work. On the flip side, it revs out so much more effectively and if you don’t feel like shifting, you don’t have to! 

Another aspect we like here is you’re getting more 450-esque power but without the added weight and inertia of a big 450. No, it is not equal in power to a 450. But, it closes that gap a little more without any weight gains or adding any handling quirks. If anything, this free-revving power makes the bike feel a tad lighter and not as lethargic. This package almost gives us a glimpse of what a YZ350FX might feel like… almost. 

Installation is very simple. Simply unbolting the old head and dropping this one on is all it takes. The valves are ready to go so you don’t have to worry about shims and measuring clearance a million times trying to line it up. This complete head assembly is also designed to run on pump gas, which leads us to believe the bLU cRU had durability in mind when building this up. We’ll continue to run it and put time on it and provide a durability report/update when the time comes. Yamaha’s durability regime is pretty extensive and very rarely do we see them produce anything faulty so we expect nothing less with this piece of equipment.

If you were to buy all of these parts in stock trim, the total cost would be ~$1,300, just $800 less than what the complete GYTR Kit is available for. Not to mention, the GYTR Head comes with the entire valve train preset and ready to go. Also, by going this route, you do have the resale value of either the stock components or the GYTR components when finished with them, something you wouldn’t have with standard porting or most other mods. This too helps make sense of justifying the cost, though is there really ever a need to justify spending money on dirt bikes? We think not.

The 250FX powerband was a little short and limited by the transmission spacing for a high-level racer--but now it’s broadened out. There is more torque and bottom end power to lug the bike, but the top end is also much improved. As a fairly high level GP racer, I previously would really only consider racing a YZ250F motocrosser in favor of the more aggressive power delivery and a close ratio transmission, even without a sixth gear. However, this GYTR mod really opens up the opportunity to feel and be competitive on the FX model all while having the benefits of a 6-speed transmission. And you will feel all the same benefits on the YZ motocross bike in the power department in a class where power is everything.