With a little routine maintenance the ’12 YZ250F continues to perform like new even with 25 hours on the clock.
When it comes to performance motorcycles there isn’t a genre of machine that gets abused more than 250 class four-stroke dirt bikes. Since these quarter-liter machines are designed to race and lack the stout bottom-end and mid-range of a 450cc bike they spend the majority of their time at wide open throttle with the engine zinging off the rev-limiter. That’s why they need a bit of attention to keep em’ running in top shape – including our 2012 Yamaha YZ250F long-term project bike.
Aside from the engine, the suspension is the next major componentry to need maintenance—especially around a fast, bumpy motocross track. And with just over 20 hours on the YZ250F engine clock the damping character of the fork and shock had degraded and became inconsistent-feeling after 20-minutes or so of hard riding. Plus the left fork seal was leaking. So we yanked it off and brought it to a local Southern California shop for service.
It’s surprising how quickly the stock fluid inside the fork breaks down. Regular rebuilds help keep it feeling fresh and new.
Irvine, California’s Garageworks Suspension specializes in motorcycle and mountain bike suspension service and repair and since it’s just a few miles away from our office it was a logical choice. They began by disassembling each component and giving it a thorough cleaning. Since we spend the majority of time playriding for fun, we didn’t feel the need to change the spring rate or modify the valving for our weight (165-180 pounds—heavier than what the stock suspension is set-up for). However, Garageworks has the ability to do both according to the rider’s desire.
Once all the parts were cleaned and fork seals replaced it was filled with Maxima Fork Oil (5WT). The shock was topped off with Maxima Racing Shock Fluid to OE spec. The reservoir was also recharged with nitrogen. Turn around time was quick and the suspension was ready to pickup the next day. These days bikes come from the factory with very little grease in the bearings and suspension pivot points off the assembly line, so we put a few dabs of Maxima Waterproof Grease to ensure the chassis stays nice and tight.
While our wheels were off the bike we mounted up a new Bridgestone M403 Intermediate Front Tire (80/100-21) and Bridgestone M204 Soft-Intermediate Rear Tire (110/80-19). We chose to run Bridgestone rubber tires as they offer borderline absurd levels of grip on virtually all terrain. Plus the carcass of the tires offers tremendous feel. Lastly durability is a strong point too.
After the chassis was all dialed in we gave the powertrain some love by changing the engine oil and filter. Since the YZ engine is subjected to such heavy loads at high rpm we like the peace of mind knowing that we’re using premium engine oil in the form of Maxima Maxum4 Blend Oil (10W-40). This semi-synthetic lubricant is compatible with the gearbox and won’t break down quite as fast as conventional lube.
We hate cleaning air filters. But with Maxima Air Filter Cleaner the process is a total breeze. First, spray the pleasant smelling aerosol formula onto the filter. Next rub it in with your hands and let it do its magic for 30 seconds. Lastly, rinse with water and wham the air filter come out looking brand new. Once the filter is dry we oil it with Maxima FFT Foam Filter Treatment. However, Maxima also produce spray-on filter oil for added convenience (Maxima Fab-1 Spray-On Filter Treatment).
At the track the YZ instantly felt brand new again. The suspension performance was restored and it didn’t fade anymore during a moto. As always we’re blown away by the performance of the Bridgestone rubber. In fact the rear tire has so much grip that it is almost impossible to spin on all but dusty hard pack terrain. Though we noticed that the front brake didn’t feel quite as sharp as we remember, so we’ll address that in our next report.