A very common question asked by new riders or by people who have never owned a 250 four-stroke motocross machine. First of all, it depends on the year of the dirt bike you are looking at. The 250Fs changed rapidly from the early years to now, and many of them had problems that needed to be resolved.
Although the manufacturer struggled with its high-performance quarter-liter four-strokes, Yamaha had practically solved it from the start. They were the first to release a 250cc 4-stroke motocross motorcycle (YZ250F) in 2001, which is 3 years before any other manufacturer jumped on the band wagon.
The Yamaha YZ 250F became an instant hit once riders started to win with them. In 2001 and 2002 the bike came with manual decompression so sometimes it is a chore to start the bike. But the only real problem the bike had was in ’01 with a weak crankshaft that broke down on some bikes. In 2003, the Yamaha 250F automatic decompression chamber. Until 2006 the bike had no problems. The ’06 YZF had a valve issue, but Yamaha recalled all that were shipped. Riders who have had or have been around 250F 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 manufacturers. 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 fat burgers. By 2007, companies (excluding Yamaha) began to discover the problems in their 250F …
If you’re looking to get a 2008 250F or newer and you’re deciding based on reliability, just pick a color. Actually, almost all 250Fs are now reliable IF, AND ONLY IF, you take care of them. Regular maintenance on a 250 four-stroke is very important and will make it last much longer. There’s no reason you can’t get more than 50 hours in high-end stock, as long as you’re not a pro or wear it on the limiter all day.
Maintenance means changing the oil every 5 hours or so (oil filter every two oil changes), cleaning the air filter every 1-2 trips, believe it or not, cleaning your bike will make it last longer, lubricating and cleaning your chain on every trip. and regrease the bearings 1-2 times a year. There are a few more things you need to do, but just doing these simple things will allow you to drive your 250F much, much longer.
As soon as you get the key maintenance steps, there are only a few things left to do to make sure your motorcycle stays in tip-top shape. It is extremely important to keep the valve train in good working order. To be sure of this, the valve clearances should be checked at least once a year (preferably every 20 hours of operation). Contrary to what most people think, the timing / cam chain needs to be replaced with a new one every year. If the chain breaks or seizes, the valves are also blocked and will be hit by the piston, causing massive damage to the engine. Buying a new supply chain is cheap insurance, so keep that in mind. I will delve deeper into these topics in future articles.
Aside from normal maintenance, choosing the right bike depends mainly on its history. If you’re buying a new 250F, it’s not a big deal, but buying a used one can be difficult. A good bike to buy is one that is clean, has few hours to work, has been properly maintained, and the owner is not trying to hide anything.
Good luck and remember that maintenance is more important than anything else on a 250cc 4-stroke motocross bike!
-Tom Stark
PS See the official article on Motocross Hideout: the most reliable 250F
