A very common question asked by new riders or people that have never owned a 250 four-stroke motocross machine. First of all, it depends on what year dirt bike you are looking at. 250F’s rapidly changed from the first years until now, and many of them had problems that needed to be solved.
Although the manufacturer’s had problems with their high-performance quarter-liter four-strokes, Yamaha pretty much had it figured out from the beginning. They were the first to come out with a 250cc 4-stroke motocross bike (YZ250F) in 2001, which is 3 years before any other manufacturer’s got on the band-wagon.
Yamaha’s YZ 250F become an instant success once riders started winning on them. In 2001 and 2002 the bike came with manual-decompression, making it a task to start the bike at times. But the only real problem the bike has ever had was in ’01 with a weak crankshaft that would go out on some bikes. In 2003 the Yamaha 250F came automatic-decompression. Up until 2006 the bike had no problems. The ’06 YZF did have a valve problem, but Yamaha recalled every one of them that was sent in. Riders that have had or been around 250F’s know that Yamaha was always the most reliable in the early years, even if it wasn’t the most powerful.
2004-2006 were embarrassing years for the other manufacturer’s. Kawazuki’s KXF/RMZ250 was a nightmare on wheels, especially when not properly maintained. Honda’s CRF250R often ate valves like Americans eat McDonald’s grease burger’s. By ’07 the companies (excluding Yamaha) started figuring out the kinks in their 250F’s….
If you are looking to get a 2008 or newer 250F and are deciding based on reliability, just pick a color. Really, pretty much all 250F’s now are reliable IF, AND ONLY IF, you take care of them. Doing regular maintenance on a 250 four-stroke is very crucial and will make them last much longer. There’s no reason why you shouldn’t be able to get 50+ hours on a stock top-end, as long as you aren’t Pro or riding it on the limiter all day long.
Maintenance means changing your oil every 5 hours or so (oil filter every other oil change), cleaning your air filter every 1-2 rides, believe it or not cleaning your bike will make it last longer, lubing and cleaning your chain every ride, and re-greasing the bearings 1-2 times a year. There are a few more things you should do, but just doing these simple things will allow you to ride your 250F much, much longer.
As soon as you get the key maintenance steps down, there are just a few things left to do to make sure your dirt bike stays in tip-top shape. It is extremely important to keep the valve-train in good running order. To be sure of this, the valve clearances should be checked at least once a year (every 15-20 hours of ride time to be safe). Contrary to what most people think, the cam/timing chain should be replaced with a new one every year. If the chain breaks or seizes, the valves also seize and will be hit by the piston, causing massive damage to the engine. Buying a new timing chain is cheap insurance, so keep that in mind. I will get more into these topics in future articles.
Other than doing the normal maintenance, choosing the right bike mostly depends on its history. If you’re buying a new 250F then it’s no big deal, but buying a nice used one can be difficult. A good bike to buy is one that is clean, has low hours, was properly maintained, and the owner isn’t trying to hide anything.
Take your 250F’s to the track with a Dirt Bike Carrier.
Good luck, and remember that maintenance is more important than anything on a 250cc 4 stroke motocross bike!