TWO-STROKE TUESDAY: ROCK RIVER’S CYCLE TRADER YZ250

The sport of motocross is becoming more and more like stick-and-ball sports. Just as baseball grooms its young up-and-comers in the minor leagues, motocross teams are doing the same in the amateur ranks. Scouting motocross talent for the next big thing can bring results, which in turn brings big-money sponsors to the table. This is not a one-sided deal. For an amateur rider, getting signed while still riding the Grapefruit Circuit is like discovering a gold mine. The riders get top-notch equipment, advice from men who know, financial support, and the fast track to the big time. At the end of 2014, Team Rock River Cycle Trader Yamaha made such an investment in Timmy Badour.

The powerplant of the Rock River YZ250 was massaged by C4MX. Bolt-on power came from FMF, Boyesen and K&N.

What better way to groom a rider than to give him a chance to race on a true-to-life AMA National track—not on a weekday and not at the amateur race the day before, but right in the middle a full-blown AMA 250/450 National. The problem is that the AMA only allows licensed AMA Pros to enter an AMA National. Timmy Badour wasn’t ready to go up against the might of the factory teams or the clout of the AMA rule book, so what did Rock River Yamaha do? They signed him up to ride the special two-stroke exhibition race at the Glen Helen National. Racing in the FMF-sponsored Two-Stroke Challenge meant that Timmy would race on the same AMA National track as the heroes, in front of a massive crowd of fans, and be the first race of the day. The problem? Timmy didn’t have a two-stroke. That is where Rock River stepped in to make it happen.

The XTrig clamps have a slot cut in them for more equal clamping surface in order to not disrupt the internals.

The Rock River YZ250 project started with a brand-spanking-new 2015 Yamaha YZ250. It came right off the showroom floor of Rock River Motorsports in Johnson Creek, Wisconsin. The Rock River team put together a laundry list of team sponsors that anted up for the build, along with some other companies that wanted to support the cause. By the end of the day, Timmy had raced on one of the most challenging courses on the AMA circuit and come away with a fourth-place finish. Timmy got some good experience. Timmy has recently transitioned from racer trainer at Matt Walker’s Moto X Compound in Culloden, GA. More information about the Moto X Compound HERE.

With Timmy’s work done, it was time for MXA to step in and take the reins of the Rock River Yamaha YZ250. In stock trim, the YZ250 is hard to beat. We usually just bolt on an aftermarket pipe and oversized front brake rotor to make the totally refined, if a little dated, YZ250 race-ready. The Rock River team went a few steps further to accommodate the massive hills and competition at the Glen Helen Two-Stroke Challenge.

The more power you have, the more brakes are needed. Galfer came to the rescue with a 270mm front rotor.

ENGINE: The YZ250 engine was sent over to C4MX for a facelift. C4MX did not go whole hog on the engine, just a few simple tricks to make it purr. An extra base gasket was added to fine-tune the deck height of the high-compression Vertex piston to match the head perfectly, which had been machined off by 30 thousandths. A Boyesen Rad Valve, K&N filter and FMF Factory Fatty pipe were installed for bolt-on power. Through its veins flowed the great-smelling power of VP Racing C-12 fuel (a must-have for a high-compression two-stroke setup).

What can we say? The MXA test riders loved this engine. It had improved power across the board and was easy to ride. We liked that the clutch did not have to be abused, as the bottom-end power was snappy out of corners. Over-rev was increased, which extended our shift points and made the engine hit harder when shifted at peak.

A milled head, extra base gasket and a Vertex piston was all C4MX did to make the YZ250 purr.

SUSPENSION: Enzo is a big help to the Rock River Yamaha AMA National team, so it was only natural that they would work on Badour’s YZ250. Enzo re-valved and resprung the suspension front and rear. They also installed their proprietary spring tubes in the forks, which replaced the stock spring perch. The rear shock got an Enzo high-speed adjuster.

The Powercore 2.1 FMF silencer is longer than the typical two-stroke silencer, but performs better than ever.

Although the suspension was set for a welterweight at Pro level, we were still impressed with how the suspension worked for our heavier test riders. Both the front and rear suspension had a fluid progression, with enough bottoming resistance to allow for Glen Helen’s big hits and infamous rock walls. The slow-moving suspension was confidence-building, as the MXA test riders could react to what the bike was going to do. In stock trim, the YZ250’s front end is great for all levels, except an AMA National track on race day.

The Kayaba SSS suspension is the best on the market and was made even better with Enzo revalving the front and rear.

OTHER UPGRADES: It took the efforts of a host of aftermarket companies to morph the YZ250 into a full-fledged race bike. Rock River mounted up ODI bars and grips, along with ARC levers. Dubya provided Excel A60 rims mated to Dunlop tires and an oversized Galfer front brake rotor. A Works Connection Pro Launch start device was installed, along with a Guts Racing ultra-light Phantom Zero Gravity seat. The stock footpegs were replaced with Torc1’s wide-platform Voltage footpegs.

WHAT DID WE REALLY THINK?

One of the Yamaha YZ250’s greatest attributes is that it has been refined over a 10-year period. When Yamaha found a problem, they fixed it; however, Yamaha did not mess much with the overall package. If it worked, they left it alone. The result is one of the best race bikes on the planet. An Amateur rider can roll it off the showroom floor and take it directly to a race. It’s that good. But racing on an AMA National track is asking a lot from a stock bike. That is where Rock River stepped in to elevate the YZ250’s game. There is nothing they did that you can’t do to your Yamaha YZ250, regardless of its age. We liked where the money was spent.

VIDEO OF ROCK RIVER’S CYCLE TRADER YAMAHA YZ250