Our YZ250F’s reliability matched its excellent performance, and we kept our aftermarket mods simple and fun.
It’s no wonder that Yamaha has seen a massive surge in sales for its YZ line of four-stroke motocrossers.
Completely revamped in 2014, the YZ250F dominated the class with its new fuel-injected, rearward-inclined engine and all-new bi-lateral beam aluminum chassis, easily winning Motorcycle.com DirtBike of the Year honors. With its new, class-winning foundation, the 2015 YZ250F was more a case of evolution than revolution. Yamaha fitted the 2015 with a revised exhaust cam to make it easier to start when warm, revised the ECU settings for smoother low-end response, fitted a new piston for better oil control and coated the 250F’s titanium exhaust valves for better durability.
After spending the past several months enjoying the 2015 YZ250F’s lightning-quick engine and razor-sharp handing, we can attest to the fact that it is a pretty durable moto tool as well, but that didn’t stop us from making a couple mods here and there just to keep things interesting.
It all started this past November when DirtBikes.com test rider Ryan Abbatoye seized the bike in an attempt to qualify for the season finale of the 2014 GEICO EnduroCross Series at Citizens Bank Arena in Ontario, California. Not wanting to leave the bike stock, we came up with a few parts and pieces from various sources to give the YZ just a bit more racing acumen than the stocker. However, it was decided that we would stick to bolt-on parts only. No major internal modifications of the engine or suspension would be allowed. (Sorry folks, those Precision Concepts suspension stickers on the forks are just decorations)
While we didn’t go inside the engine, a new pipe was the first order of business, and we chose a Yamaha GYTR system made by one of the best names in the business, FMF Racing. Our exhaust system was composed of a GYTR by FMF MegaBomb head pipe and a GYTR by FMF Titanium RCT Factory 4.1 muffler. Yamaha claims that the exhaust system can provide as much as a three-horsepower boost to the YZ250F’s power output while also quieting exhaust noise by as much as 1.5 dBA. However, it wasn’t more horsepower that we were after, but rather more torque, and the MegaBomb is designed specifically to deliver the increased torque of a longer header without sacrificing top-end overrev.
The GYTR by FMF Titanium RCT Factory 4.1 muffler was the perfect way to cap the MegaBomb header. The muffler features FMF’s patented Resonance Chamber Technology, which is designed to retune exhaust pressure for increased performance. The muffer’s core shape is also patented, and it is claimed to reduce sound output without sacrificing power. The canister is shaped to increase internal volume, which allows for more sound-absorbing material to be packed inside it. Further reducing exhaust noise is FMF’s QuietCore 94 dBA insert. Even so, we would be remiss if we didn’t say that both the MegaBomb and the Titanium RCT Factory 4.1 muffler are sold as closed-course items only.
Beyond that, we set out to make our YZ250F just a little more crash-proof since EnduroCross is notorious for bending, breaking and cracking exposed parts. The first order of business was to incorporate a heavy-duty skid plate to protect the bottom of the engine cases, which are exposed in-between the YZ’s aluminum lower frame rails—a sure invitation to disaster by the gnarly rocks and logs that are commonplace on a GEICO EnduroCross course. We had planned to use one of P3 Composites’ cool-looking carbon fiber skid plates, but a shipping error—caught only at the 11th hour on the day of the race—left us scrambling for another one. We obtained an MSR skid plate through Chapparral Motorsports. The thick, aircraft-grade aluminum MSR plate isn’t the prettiest skid plate we have ever seen, but it certainly gets the job done just as well, boasting a wide forward wing on the right side to help protect the YZ250F’s water pump, reducing its vulnerability in the event of an impact. The plate also features a large drain hole on the underside to facilitate transmission oil changes.
However, we did use one of P3’s carbon fiber composite four-stroke pipe guard/heat shields. Light and beefy, the P3 part offers more coverage than the stock Yamaha heat shield, and it is made with P3’s special blend of high temperature resins for long life and high strength. A high-temperature coating on the backside of the guard is claimed to resist heat better, helping to keep the pipe from burning the rider’s pants and boots protected. The shield also covers more of the pipes exposed area for better impact protection. We’ll take the insurance, since there’s nothing like shelling out around $500 for a trick titanium headpipe, only to have it ruined when it is dented in a crash. Lastly, the P3 guard simply looks cooler than the stock part!
Because Abbatoye is a big fan of BRP’s products, we fitted the YZ250F with the company’s Pro SX top triple clamp. BRP says that the one-piece 6061-T6 aluminum clamp offers a wide range of options to accommodate different rider ergonomics. BRP manufactures its triple clamps to deliver a bar position with a greater “RTS” (Relative to Stem) distance than stock triple clamps. The BRP bar mounts are reversible and can be ordered in in three different heights. In some applications, the bar mounts are also available in different offsets as well.
BRP claims that the SX clamp is stronger than the stock clamp while weighing roughly the same. The fork bores are precision-machined and utilize a two pinch bolt design that increases the clamping surface on the forks to better resist fork twist in the event of a hard landing or crash. Our clamp came in BRP’s signature black-anodized finish.
We also fitted a BRP Pro-Line chain guide to the lower swingarm. BRP recently redesigned the Pro-Line for better chain guidance and reliability when riding in extreme conditions. Made from UHMW-PE polymer, the chain guide is said to offer reduced friction, better impact durability and wear resistance than the stock chain guide. BRP even backs it up with a 1-year warranty against wear or breakage.
We wanted to spruce up the stock bike’s appearance, but since the stock graphics on Yamaha’s YZ models are now impregnated into the tank panels, the only real choices are to lay your custom graphics over the top of the stock graphics (not a good idea) or start over with a new set of panels to give you a blank canvas for custom graphics. That’s what we did, and Acerbis made it easy. The Italian company has a rich history in the manufacture of high-quality plastic that meet or exceed the quality of OEM plastic at a more affordable price. We picked up an Acerbis standard plastic kit and then let Abbatoye choose whatever custom graphic design he wanted. We kind of had to, since he was going to be the one to produce them through his own company, RADCustomGraphics. What we ended up with was a little bit of surprise, “the Pizza Factory Special,” done in honor of Abbatoye’s friend and local Pizza Factory owner in his hometown of Ridgecrest, California. All we can say is that the graphics looked great, and they have proven to be extremely durable over the past several months.
Last, but far from least, we addressed the clutch and brake levers, going with ARC’s tried-and-true unbreakable levers and perches. In case you’ve never seen them (and we doubt it) the ARC levers feature an ingenious design that incorporates a beefy spring-loaded billet–aluminum pivot on each lever, allowing the lever to pivot forward when the handlebar hits the ground, thus preventing the lever from snapping off and leaving the rider stranded. Abbatoye also topped of the bars with his favorite A’ME Half Waffle MX grips.
So, long story short, we expected to be patting ourselves on the back last November after Abbatoye made the Ontario EnduroCross night program and then made the main event. Trouble is, it never happened. After struggling in his heat race, Abbatoye was battling for the win in the Last Chance Qualifier when he got out of shape in the matrix section and catapulted himself over the bars. Fortunately, neither he nor the bike were damaged, but that ended the EnduroCross dream.
Since then, however, we have beaten our upgraded YZ250F mercilessly on motocross tracks and on a couple closed-course off-road circuits, and it has taken all the punishment without buckling. Naturally, from a pure power delivery standpoint, the GYTR by FMF exhaust system makes the most noticeable difference. The header and muffler don’t necessarily make the YZ sound any meaner, but throttle response and low-end snap are significantly cleaner, making the pipe and muffler a worthy upgrade in our book. We also highly recommend the ARC levers, as both our fast pro and our ham-fisted vet novice have tested their integrity repeatedly, and we have yet to see them fail.
But while we could have gone the full catalog route and blinged our long-term YZ250F to the max, we simply didn’t feel the need. Simple changes yielded all of the performance and reliability we were after in the beginning. When you have a great bike to start with, finding a way to gain major performance improvements with simple bolt-on parts becomes all the more difficult.
2015 Yamaha YZ250F Mod List
GYTR by FMF MegaBomb header, $349.99
GYTR by FMF Titanium RCT Factory 4.1 muffler, $599.99
See your Yamaha dealer or visit www.yamaha-motor.com
Aluminum Skid Plate, $152.95
Carbon fiber heat shield/headpipe cover, $69.95
SX triple clamp, $219.95
Pro Line chain guide, $79.95
Yamaha YZ250F standard plastic kit, $134.95
Yamaha YZ250F levers and perches, starting at $64.95
MX Half Waffle grips, $7.95