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.
What do you get with a bin full of dirt bike parts and an eager mechanic looking for excitement and satisfaction? A great project rebuild! If you are a dirt bike grease monkey like me who not only likes riding their bikes but sometimes working on them too then this is for you. I enjoy project rebuilds and love the oh-so greatly anticipated finished product even more. Ever since I got into dirt biking I have gained more knowledge about how they work and how they are put together. So after doing many rebuilds myself I thought that I would share the experience with you fellow riders.
I bought this 2003 Yamaha YZ250F in pieces as a project bike thinking that I would have some fun and get some more experience putting another bike together over the next month after I bought it. It came needing a complete new top-end at the least. I managed to get one and put the engine together in a reasonable amount of time. I then slapped the engine in the frame and started the process of puzzling the rest of the bike back together; this is where the fun started. It only took a few short minutes of bolting parts on to find that there was stuff missing. The more I put together the more parts I found that were missing or broken, and they were not all at the same time. So one-by-one I had to buy parts that I needed to piece this thing back to its somewhat original form. These parts consisted of, including engine parts, clutch plates, radiator shrouds, timing chain, timing chain slider, a different piston, head pipe, a couple crank bearings, engine/frame mounts, air filter, cylinder head breather hose, chain, gas tank, clutch perch assembly, a shift lever, and maybe a couple other miscellaneous things. Figuring out that we had to find and buy these parts got a little frustrating because we were told that the bike was complete and that it just needed a new top end.
Well, after weeks of picking at my wallet this bike has finally been put together and is running. It just needs a couple things put on to be ride able. So once I get those together I’ll take it out for a spin. The process was long and somewhat miserable, but I think I learned a lesson and gained more experience and knowledge about these modern four strokes that basically took over the world. In the spring, if not sooner, I will be putting on some new bling to make this baby look new, but as of right now it’s a clean bike that runs. Thanks for checking out this rebuild process, and make sure to check back in the near future for another bike rebuild! (If you liked this article make sure to check out my other rebuild, “I Rebuilt My YZ125 In A Closet!?”
P.S. I might update this article with some pictures and/or video once I get this bike looking good. Questions and comments are welcome.
When I got the bike (as you can see, I had my work cut out for me):
Pic of the damaged cylinder head:
After I cleaned it up and the engine was together in the bike:
Put the wheel and handlebars on:
The bike put together (added sub frame, carb, electronics, old plastics, seat, exhaust, cables, etc.):
If you’re looking to get into racing motocross at AMA sanctioned tracks and are wondering which bike to buy for the 250cc class, then pay attention. Although the four-strokes have pretty much taken over the motocross market lately, it seems that there are a lot of people trying to bring back the two-strokes, and it seems to be working. AMA made it legal so that a 250cc two-stroke can run in the same class as a 250cc four-stroke. Now, the first reaction I had when I heard of this was without doubt to pick the two-stroke. I looked into it a little bit more and came up with this….
Now most people would think that a four stroke with the same displacement as a two-stroke would not have a chance, and that is why the AMA originally allowed the four strokes to run a bigger engine in 1998. This isn’t the case, due to the fact that companies have put so much more money and effort into making the modern four-strokes extremely high-performance. Some riders that do not like the two-strokes snappy power will often stick to the four-stroke 250 just because they like their broad and easy-to-ride power-band. A 250 two-stroke may have more peak power, but when the day gets long and the track starts to get really rough, that’s when the four-stroke starts to shine. Due to the tractability in rough and slick conditions, the four-stroke will be easier to ride faster late in the day. That doesn’t mean it will be faster than a two-stroke though…
Two-strokes are fun to ride because they have a bigger top-end “hit” compared to the four-stroke. If you keep the two-stroke on the pipe then it will definitely be faster than the 250F, as long as the conditions aren’t too rough. For those of you that want more, snappy power, and a lower center of gravity, then go with the two-stroke. It may not always have the traction that a four-stroke has in rough or slick track conditions, but the horsepower makes up for it.
So Which Bike??
After reading the info on each bike you would probably guess that the two-stroke is the better bike for AMA racing, and my answer for that would be, “Yes.” Clearly, it’s a faster bike if the track is in good shape, it handles better because it has a lower center of gravity and is a 2 stroke, it has a lighter front-end allowing you to skim over whoops and bumps, and it smells good. But I will say that if you are a four-stroke guy that doesn’t like the snappy-feeling power-band on the two-stroke, then you will be fine on a 250F. The 250F is by no means slow, and any good rider should be able to win on it. My choice would be to ride the 250 two-stroke though because it’s faster, and it’s a new rule that I would take advantage of. Good luck, and no matter what stroke you ride, have fun!!
This past decade saw much change and technological advances compared to the 1990’s. The Pro National scene went from 99.9% of the bikes being two-stroke (Yamaha’s YZ400 was about the only thumper out there in the late 90’s). 2001 was the beginning of the end for the 125 2-stroke because of the YZ250F, and soon after, the other companies followed suite. By 2006 the scenario had done a complete 180. Within the past 10 years, there have been some atrociously made bikes, as well as the best bikes ever made. This list may not include the entire globe, but should cover the United States, along with many other countries that have similar inventory of bikes. My list is objective and unbiased; I am going by which bikes are being sought after and bought the most, both new and used.
5. Yamaha YZ250
Yamaha is the only Japanese manufacturer that still imports their two-stroke motocross bikes to the U.S.. They have had it together the entire time, but the YZ250’s best years are 2005 and newer. The lightweight aluminum frame and updated suspension (2006) makes the bike nimble, quick, and easier to ride. Power right out the box is excellent for almost any amateur, so there really isn’t much you need to do for it to be competitive, other than a suspension re-valve for your weight and riding style. The YZ250 has quite a bit of bottom-end power for a 2-stroke, and has plenty up top. You can move the power-band around with an aftermarket pipe if you don’t like the stock curve. Probably the best modification for engine performance is porting. It’s relatively cheap, and if you get it done by the right person this bike will absolutely rip.
4: Yamaha YZ125
I know I said that four-strokes have dominated the pro motocross and supercross scene the past several years, but that doesn’t mean people don’t buy two-strokes anymore. In fact, riders are realizing how expensive four-stroke motocross bikes can be if there is a major failure, so they’re moving back (or to) two-strokes. Don’t fool yourself, the 125 two-stroke is a very fast bike, even stock, when properly tuned. When James Stewart entered the pro-scene on a 125, his lap-times were often as fast or faster than a lot of the 250cc riders because he knew how to ride his KX125 so well. He continued to beat four-strokes in 2004 when 250F’s started becoming “the bike” to race, so you know the bikes wasn’t lacking, that much.
The Yamaha YZ125 has reigned has “the bike” to get in the 125cc-class for many years now. It may not have the best of everything, but as an overall package it’s arguably one of the best motocross bikes ever because it is versatile. Although, the motor hasn’t changed much since 2001, and the chassis/suspension since 2006, there really isn’t a whole you need to do to this bike to race it.
Unlike most other 125’s, the YZ125 has some bottom-end power. So if you’re not afraid to finger the clutch a little, you can turn it into a woods weapon because it is so light. The center of gravity is lower than four-strokes, adding to its maneuverability. I like riding both two- and four-stroke dirt bikes, but getting on the pipe and ripping it up on a YZ125 is just too much fun!
This bike also makes my top 5 list because of how easy maintenance is, as well how cheap it is to repair if something major happens because of less moving parts. A four-stroke engine costs 3-4 times as much if something catastrophic happens, especially if you have a shop do the work. On a two-stroke, as long as you change the oil regularly, a top-end kit (usually just a piston, rings, gaskets, etc.) costs around $100-150. Even if your cylinder gets scored you can re-plate it to new condition for about $200.
3. Yamaha YZ450F
You guessed it, another Yamaha. Not only are its two-strokes good, but so are the four-strokes. The first year of the YZ450F was 2003 (superseding the YZ426F). This is when the bike was titled “Impossible To Ride.” It did have a lot of torque just because it’s a 450, but the top-end power was unbelievable. It was hard to hang on to the bars for less-experienced riders (Here I’m thinking, “supermoto, supermoto….”). Well, it is a little harder to ride than most others in its class, but any 450cc motocross bike is going to have a lot of power if it’s fresh. Don’t let all the “internet hype” get to you, it was still a great bike. In fact, some say it had the best 450cc from 2003-2005.
The second generation YZ450F got even better (for the most part) in 2006 with the all-new aluminum frame. This reduced weight and helped with handling (more on that in a little bit). The power curve was changed considerably, changing from a top-end monster to a more mellow beast. Some complained, others loved it. Don’t worry, the engine is probably the easiest to change, it just takes a little dough.
Moving on to other things, the YZ450F’s suspension is good in stock form. Just make sure it has the correct spring rates for your weight and riding style. The handing on this bike is said to be an issue. Supposedly the steel frame was to blame and made it feel heavy and turn slower. I mentioned that 2006 is when Yamaha switched to aluminum frames for its four-stroke motocross bikes, and doing this resulted in better turning and handling for this bike. 2010 is really when handling was a positive for the YZ450F with the new bilateral-beam frame and centralized weight. It made it feel more like a two-stroke, but not quite because of its weight.
2. Honda CRF450R
Red has always been a popular color, and there’s a reason why; they make high-performance bikes. Honda’s CRF-R line is near the top in almost every performance category, but the thing that has held them back from others is the reliability. Granted these are full-on race-bikes we’re talking about, but some of Honda’s early model four-stroke motocross bikes have had some problems causing failure much sooner than others in its class. The valve-train malfunctions were primarily on the CRF250R its first few years, which is why I chose the CRF450R to be on this list.
The first year of Honda’s 450cc four-stroke motocross bike was 2002, when Yamaha was still making the YZ426F, so it had a little edge. The CRF450R helped bring down the two-stroke legacy in pro racing. You know something is wrong when Kevin Windham on Honda’s 450R is passing Ricky Carmichael (aka the GOAT) on an RM250 two-stroke. No disrespect to Windham because he is one of the smoothest riders in the history of motocross. It’s just that “RC” is clearly a faster rider when he is healthy.
Honda has been known to make dirt bikes that handle well. The bilateral-beam aluminum frame on the CRF450R is just the same as far as four-strokes go. Point it and it goes there. The ergonomics are great for most riders as well. Suspension has always been on par or better than other bikes in its class. Over the past few years Honda has been making their 450 easier to ride for more riders right out of the box, bringing out the fuel-injection (second company to do that behind Suzuki’s RMZ450). There have been some glitches, but then again, what bike doesn’t when it introduces something completely new? Overall this is a very powerful, easy to ride fast, and great handling bike for riders of all experiences, which is why it’s so popular.
1. Yamaha YZ250F
Yep, that’s right. The YZ250F is The Top Motocross Bike of The Decade. Surprised? You shouldn’t be. It’s the most popular 250cc four-stroke motocross bike, and for many good reasons. It was the first one made, and by a few years two. The first year of Yamaha’s 250F was 2001, and it was an instant success. People saw how powerful it was and how much torque it had compared to a 125 two-stroke.
Yamaha knows how to make a four-stroke motocross bike, plain and simple. Their 250F has always been known as the most reliable out of its entire class, even in its early years. It was a bit porky and hard to start at times in ’01 and ’02 with its manual decompression, but once they figured that out in 2003 this bike was a force to be reckoned with. No more clutching out of every corner, bogging out and casing jumps, or having to perfect your shift points. Once the pros started riding them, everyone wanted one. The thumping and thundering sound of a four-stroke ripping up the track is loved by many, but hated by many as well.
The YZ250F’s engine characteristics weren’t number one once all the other companies figured their 250F’s out, but it was mainly lacking some down-low. It was a pretty easy fix with an aftermarket exhaust or cams, but that’s only if you wanted it easier to ride with a smoother power-band. Yamaha has always had great suspension, and the YZ250F is no different. Ready to race out of the crate as long as the spring rates fit your weight and riding style. Ergonomics have been a positive for the most part. The early models were a little chunky, so the newer you get the better.
Handling is something that people always complained about, but I think that most of the propaganda came from people reading magazine reviews. Statements like “It can’t turn right,” or “It stands you up in corners” are usually from people that have never ridden the bike. It’s not as dramatic unless you are a Pro or fast A rider. You can also re-valve the suspension, change bars, triple clamps, springs, ride height, and many more things to get it to corner. Other than that, the YZ250F is a great bike and is very reliable. There are riders that get 200+ hours on stock and with everything still in-spec if they aren’t racing it hard. That’s saying something for a high-performance, high-revving machine.
Now remember, this list is the top motocross dirt bike of this past “Decade”. If it was within the last few years this list would more than likely be completely different. These bikes have been the most popular for the most amount of time in the past ten years. The reason why I did that instead of the last few years is because not everyone has the budget to buy that new of a bike. Some riders that are looking to start out in this extreme sport want cheaper, yet competitive and reliable bikes. I want to give those riders (YOU) the benefit of knowing these things so that you can stay with the competition.