YZ250 Off-Road Dream Build

Story and Photos by Trevor Hunter

Yamaha’s YZ250 is a staple in the moto industry with a rich heritage in both the MX and Off-Road racing realm. Since the mid-2000’s, the YZ has held the same basic platform with minimal updates throughout the years. However, that isn’t necessarily a bad thing. The bike is still a capable machine in the right hands and still receives praise from two-stroke enthusiasts of all kinds. With quite a few years of racing experience on the bLU cRU machines, we sought to build one out the best we could to go off-road racing.

We chose the YZ250 since its core appeals to our core better than the X model.

So why did we go with the YZ250 and not the YZ250X as the base for an off-road racer? Our riders prefer the more aggressive power characteristics of the YZ, along with an evenly spaced transmission. The YZX has a wide-ratio tranny which is good for desert riding and trail riding, but the standard moto transmission is our preferred choice for GP racing here on the West Coast. With that in mind, let’s dive into what makes up this race bike!

Enzo Racing handled the bump absorption for us.

One of the first things we did was tune up the suspension to better handle the rough and tough off-road circuits. The YZ is on the stiffer, harsher side of the spectrum as it should be for motocross tracks and riding. But for off-road riding and racing, we needed something a little softer and more forgiving as we race for 1.5+ hours at a time on choppy, square-edged, whooped out tracks. Enzo had done a previous setting for us in the past and we really liked it so we took it back to them to get the same general setup with the right spring rates installed.

The Zip-Ty version of the IMS YZ tank is slimmer and closer to stock than the standard IMS tank while still holding 3.2 gallons of fuel.

Next up, a 3.2 Gal Zip-Ty Racing IMS Tank with a dry-break setup is a must. The stock YZ tank can’t make a full race, so the Zip-Ty tank offers the extended range we need plus minimizing the pit stop times to just a few seconds. 

The VFORCE3 Reed Block is a fairly simple yet very effective mod for an YZ two-stroke.

V-Force 3 Reeds help broaden the power on the YZ and is something we’ve found to like on past YZ project bikes. The installation is a bit of a pain on these bikes, but once it’s installed, you rarely ever have to worry about it or touch it.

Flexx Handlebars offer some needed cushion and vibration dampening to our YZ XC racer. The 14* Moto Low is our bend of choice.

For more added comfort, Fasst Co Flexx Handlebars were added to the list. We’ve put in quite a few miles with Flexx bars at the controls and we’re a fan. They take off the edge and add just a little bit of extra cushion, evening allowing us to firm up the suspension slightly knowing we get the initial hit taken out of the handlebars. AME Grips were slipped onto the Flexx bars as they are soft and save our hands over the duration of a long weekend of racing.

GPR’s new V5 stabilizer and triple clamp were no brainers for high speed off-road racing.

GPR Stabilizer just debuted the new V5 Steering Stabilizer and an updated top triple clamp to make up their signature Pro Kit. The Pro Kit minimizes any rise in the handlebar with its sub-mount system, only raising it a few millimeters overall. Pair that with the low 14* Moto Low Flexx Bar bend and we have a setting that sits lower than stock, something I prefer being a smaller rider.

Motor wise, we’re running a Pro Circuit exhaust but had Bill’s Pipes in SoCal port the cylinder and head. One of our last YZ’s had this Bill’s setup and it was one of the best running YZ’s we have ridden to date. It smoothened out the abrupt bottom end hit, and transitioned that more into the mid-top with quite a bit more overrev.

Overall, it made the power more linear and easier to ride. Likewise, the Pro Circuit exhaust offers a crisp, snappy characteristic and plain just sounds good. A DT-1 Filter keeps the bike breathing fresh air through the dust and silt. 

We’ve had good luck with DT-1 Filters keeping dirt from passing through in the nastiest conditions.
Our drivetrain is composed of TM Designworks, Sunstar, and Bullet Proof Designs products.

Sunstar provided the Chain/Sprockets and we dropped down to a 48T rear sprocket. This spaces out the gears a little more and helps with the top speed. Spacing the gears out reduces the need to constantly shift and paired with the motor mods, it pulls it quite well. A Works Connection Pro Launch Start Device helps tremendously with starts keeping the front end down under acceleration. Plus, it helps my shorter legs touch the ground a little easier! 

Braking provided some rotors to help the stopping power when racing at speed.

Our tire/mousse combo goes back to something we’ve been running for years, Maxxis and Nitromousse. The Maxxis SI Tires are good all-around tires that work well everywhere and are fairly consistent and I’ve been running them for years making it a predictable tire choice. Nitromousse foam inserts are stuffed into the tires as they are some of the longest lasting mousse’s we’ve tested and they perform quite well to boot.

Our final mods were more in the protection/durability department and served as replacement pieces since our stock components were wearing out. TM Designworks Slide-N-Guide Kits are some of, if not the most durable chain guides and sliders we’ve tested and was an easy install for this off-road racer. Likewise, we paired that with a Bullet Proof Designs Swingarm Guard to help reinforce those chain guide tabs when busting through rocky terrain. Bullet Proof also supplied the aluminum Rear Disc Guard out back. 

Acerbis freshened up our look with their plastic kit, a skid plate, and the fork shoes.

Acerbis freshened up the plastic with a full plastic kit, along with a really nice Skid Plate and their Fork Lug Shoes. The Skid Plate installs with one bolt, going on and off very easily while still offering adequate protection for our application. If we were racing desert, we’d look for something a little beefier, but for Moto/GP racing, the Acerbis option offers more than enough coverage. Also, the Fork Lug shoes protect the low hanging lugs from roost and ruts, keeping them looking fresh. 

Hinson components are some of the best in the business.

Hinson provided a Clutch Cover and Clutch Basket for durability upgrades. I’ve put a few holes in stock clutch covers over the years, so the Hinson option is a little thicker and stays looking nicer over time. Additionally, the Hinson basket drastically outlasts the stock basket and helps improve clutch life and feel.

A MotoSeat Seat Cover replace the stock cover for something a little more grippy. We went with the ribbed version to help keep us in place and locked in on the bike. Megla Designs covered the graphics and we went with a stock looking theme.

Stay tuned for a riding impression and our thoughts on this package as we’ve spent some time riding and racing it over the last couple of months.

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