Jump to content
Sign in to follow this  

250f vs. 125

Recommended Posts

I know there are some differences between the four stroke and two stroke in riding styles.

What exactly are the major differences between the two? Is there major power differences?

I'm just wondering because when i start working(this summer?), a 125 is much more likely for me too purchase since they're half the price of a 250f.

Thanks for the help.

Share this post


Link to post
Share on other sites

completly different powerbands, but they add up to pretty equal power. You gotta rev out the 125 more while the 250 has a more "tractable" power band. If I were you I would get the 125 if your on a budget. Great learning bike, virtually no maintenace costs, and you can probally the same resale value as you bought the bike for if you find a good deal.

Share this post


Link to post
Share on other sites

As said above, they are completely different bikes, especially if you buy a Japanese 125.

The biggest difference between a Japanese 125 and 250F is actually the 125 chassis, its smaller and has a shorter wheel base by at least 20 - 40mm, which is a great deal. Because of this aspect alone, the bikes are VERY easy to maneuver around, almost telepathic in the corners. Because of this alternative chassis and 2 stroke motor, all 125's weigh a considerable amount less then there 250F counterparts and most of the time less then there 250 2t counterparts. This weight difference also helps in the ability of the machine to get around easier. Finally, when it comes to weight difference, you've gotta talk about rotating mass, 125's have MUCH less gyroscopic effect as the motors have hardly any large moving masses, just the crank and flywheel, which are much smaller then 4 strokes.

Now, you'd look at that list and say, WOW 125's rock!!!

Well, in terms of spec, a good 125 puts out the same as a 250F. But in terms of where the power lies, that is basically where 125's start to look like a bad idea. 4 strokes have a very even powerband from low RPM to the max, its linear and not peaky. Some people actually complain about 250F's not having that extra umph that is commonly found on 2 strokes of all varieties. On a 125, especially the Japanese ones, the power is somewhat subdued at lower RPM's, which forces the rider to use the clutch exiting corners so you can raise the RPM's into the actual power band, but the bike can still be moving at a slower speed. 125's are all about building/generating speed and maintaining what you have generated, the riding style is extremely different then that of a 4 stroke.

So, now you're thinking what else is wrong about 125's and there is one more aspect... weight balance. Because 125's are so light in the chassis and motor, there isn't enough weight over the front wheels to keep it sticking. This is resolved through the "proper" riding technique of putting your body as far forward on the seat in the corners as possible. It means you become a much busier rider on the seat, moving back and forward to help generate grip.

Everyone has pretty much moved away from 2 strokes for environmental reasons and the simple fact, its old technology that in essence doesn't have enough development life-cycle as the 4 stroke counterpart. Companies like Honda want to have constant development range and once you've done all the development you can do, you've gotta change the paradigm and thats exactly what happened. Two strokes don't exist because manufacturers were basically tired of making the same old thing year after year... kinda sucks don't it?

With that being said, 4 strokes do have a HUGE benefit; weight/gyroscopic effect. When you put that big-ass motor into the bike, you all of a sudden add a bunch of weight over the front end and over the entire bike. That added weight is a good thing, it helps keep the front planted. The gyroscopic effect helps keep the bike flying straight and lowers the twitchiness of the 2 strokes whilst in flight or even over whoops.

One more benefit of FOUR STROKES is the fact there is a power pulse every 4th stroke, meaning there are less power pulses per RPM then the TWO STROKE, which has twice as many power strokes. This is one reason why TWO strokes can produce more power per CC size, they simply produce 2 times the power per 4 strokes as 4 strokes do, makes sense? What this means to the rider is actually straight-forward, it gives the tire a break under acceleration. It grips the dirt instead of spinning on top of it. This gives 4 strokes the upper hand in traction, no comparison, 4 strokes win in that category every time.

So weight-balance, gyroscopic effect, powerband and tractability are the big four reasons why 4 strokes rock. There is no contest between 2 strokes and 4 strokes in these categories. You also get some added benefits of engine breaking, which is very nice and of course a modern chassis/suspension, which most 2 strokes don't have.

Compare the two straight up and the difference is an eye opener. The 250F is easier to ride, hands down. You can lug it out of corners, without using the clutch. You can ride the whole track in only a hand-full of gears, instead of the full range, you can even ride it in really any position on the seat, as most 250's are so well balanced, they don't even care if there is a rider on board.

Honestly, 125's are a lot of work to ride, lots of shifting, lots of generating power, lots of moving your body around, they're "busy" bikes to ride. But because of this, they are SUPER rewarding and a HUGE learning experience for anyone just starting off in MX. If you can ride a 125 quick, getting on a 250F you'll be WAY faster then if you started on the 250F from the beginning, hands down thats a fact. Also, 2 strokes are easy to work on, which makes them cheap to purchase and own. This cost differential is pretty much the only BIG separating factor between the two bikes off the track. TCO (total cost of ownership) on a 4 stroke is about double what it is on ANY 2 stroke, 125's included. So a lot of people wind up starting with 125's because they're the right thing for a beginner...

Mama don't take my 125 away, but I'll be adding an "F" to my garage soon! I'm tired of changing gears... it really wears you out! :smirk:

Share this post


Link to post
Share on other sites

I just made the switch from 125 to 250F mid season last year. I have to say that Tye's lengthy write up is spot on. The 250 is much more stable and easier to ride.

Only things I would add are: You CAN lug it around and shift less, but ultimately it goes faster and handles better if you ride it a lot like a 125. get the revs up and carry speed. It takes more upper body to muscle it through the corners than the 125, but it's so much easier to jump and track through the whoops that it makes up for it.

Share this post


Link to post
Share on other sites

I agree with the 2 posts above me, the 250f's have a better powerband and are 'easier' to ride compared to the 125.

That being said, if you are on a budget, go with the 125. Especially if you are going used, unless you trust the seller of the 250f. Last thing you want is to rebuild a top end on a f and you have no clue to do it yourself $$$.

Share this post


Link to post
Share on other sites

I know quite of old people that have 450's, but they also buy 125's because theyre so light and moveable. The guy i bought my 125 from had a 450 and he said he liked riding the 125 more, which is why he was sad when i took it from him haha

Share this post


Link to post
Share on other sites

I have both, a low hour clean 2005 kx 125 smoker and a 2011 kx 250f FI. What I will say is that you feel like your going way faster on the 125 because your carrying a lot of speed, but on the 250f your actually going faster and feel more in control. As far as tye saying the added weight helps, I really think the 250f's dont corner as well as a 125. They are easier to hit the inside ruts with because the power is so smooth, but with a smooth clutch hand a 125 can do the same. The 250f's like to try and "push" the front end in the corners, where if your up on the tank on a 125 it will carve anything up. The first thing I notice when I hop on the 250f from the 125 is how the cornering game changes completely between the two. The 125 you can cut up anywhere, the 250f takes a little more patience. 250f's do typically need to be ridden higher in the RPMS making them a second owner used bike night mare a lot of times, but with the new FI the bikes make so much power down low its rediculous. My 11 kawi I can lug third in corners with out a problem. If your on a budget get the 125.

Share this post


Link to post
Share on other sites

A couple things to keep in mind...

On the internet we love to discuss the fine details and differences of every little thing. At the end of the day if you buy either bike you will have tons of fun.

If your goal is to race and be as fast as possible your best bet is a 250f. If your goal is to have fun and not spend a lot of money the 125 is probably the way to go.

When I'm sitting at the computer browsing the web I am always thinking about buying a 250f. When I'm out riding my 125 the idea of buying a 250f never crosses my mind...too busy having fun.

  • Like 1

Share this post


Link to post
Share on other sites

A 125 will save you money in maintenance and make you a better rider. Unless you're a high-level motocross racer I would get a 125, learn how to use a clutch extensively, and have more money to get your bike to the track than in a motor rebuild.

Share this post


Link to post
Share on other sites

At 43 years old I went from EFI 450 back to a 125. It is more fun and cheaper to run. At my age having fun is more important than being competitive and broken femurs and ankles leave we not wanting go go huger over jumps anymore.

the 450 was easier to ride for sure. it also tired me out more than the 125. The 125 is fun, way more fun but slower and I am definitely faster on my 450.

It is different for younger kids than for older dudes though. My son in on 85's and he will be on a 125 for 2 years before we go to a 250F. Most fast kinds on 85's are faster than most novices, even fast novices on 250 f's. There is a reason for that, you have to learn to carry speed on a 2 stroke. 250's no so much. Ok we not talking about Barshia here were talking your typical local racing novices with no 2 stroke experience.

Share this post


Link to post
Share on other sites

I have to say that I've ridden both 125, 250 two stroke, and 250f and I have to say, hands down, the 250f is the easiest and most fun to ride!

With the 125, like stated above, there are some advantages over a 250f, but to me they aren't worth taking over the benefits of a 250f. On my 125, I was only able to do a hard 8-10 minute moto and then I was completely worked, but as soon as I got on my 250f, I was quickly able to turn 10-12 minute motos no problem! You just don't get as wasted on a 250f as you do on a 125. Simple as that!

Also, to me the higher cost of owning a 250f is well worth it because of the added benefits. But I'm the type of person that likes to tinker and mess around with the bike when I'm bored, so the maintenance isn't a big deal to me. (lets just say i tore the engine down just for the hell of it!). Some might think otherwise.

I aslo wasn't a fan of the "jumpy-ness" of a 125. To me it felt a little more unpredictable and would scare the &*%# out of me sometimes. (i'm sure we've all experienced the loop out scenario because of the last minute brap of the 2 stroke on the face of the jump). I'm way more confortable with the smooth power that comes from a 250f.

In a nutshell, I like the 250f's way more than I ever did a 125, and though I still like 125's and would never pass up an opportunity to ride one, my heart is now with the 250f.

Share this post


Link to post
Share on other sites

Having never ridden a 250f, or a four stroke for that matter, this thread makes me feel like shit for owning a 125 and trying to race against 250's at my local track...

sigh.

Share this post


Link to post
Share on other sites
Having never ridden a 250f, or a four stroke for that matter, this thread makes me feel like shit for owning a 125 and trying to race against 250's at my local track...

sigh.

Don't feel bad. There is nothing wrong with a 125. I prefer 125s over 250f and am faster on a track and in the woods on a 125. It's all a matter of riding style. If you ride a 125 to it's fullest the 125 vs 250f argument is really moot.

There is more development left on 250fs but there are also improvements that COULD be done to 125s to make them more competitive. Direct injection like the systems on two stroke outboard motors, etc. And doesn't the AMA allow 125s to be bored to a larger displacement now in the "Lites" class?

Share this post


Link to post
Share on other sites

This age old argument can be put to bed with the following statement: Winning is 80 percent rider, and 20 percent bike.

Share this post


Link to post
Share on other sites

250f vs 125 is alot like manual clutch vs automatic. I believe 4 strokes have made it alot easier for the common guy to go fast. Sometimes to easy. That results in people doing things they really shouldn't. (but it makes funny you tube stuff) Last year I saw 125's turning the fastest lap times of all other bikes on at least 3 mx tracks. That includes the open A guys. So go and tell me 125s are slower. It tells me that some people know how to really ride and others take the easy way out. (I would fall into that class) I like my 250f, but I love watching a 125 eat 450's on the track.

Share this post


Link to post
Share on other sites
Last year I saw 125's turning the fastest lap times of all other bikes on at least 3 mx tracks. That includes the open A guys. So go and tell me 125s are slower. It tells me that some people know how to really ride and others take the easy way out. (I would fall into that class) I like my 250f, but I love watching a 125 eat 450's on the track.

Well, from my experience, people who race 125's are really good riders, some of them far better then the guys who ride around on 4 strokes.

The track itself has a lot to do with how well certain bikes go. For instance, 4 strokes do better then 2 strokes when it comes to building power, so going up hills is a killer for a 125 compared with a 450. Jumps that are right after slow corners are another issue for 125's because building power quick uses a lot more energy on a 125.

Edited by tye1138

Share this post


Link to post
Share on other sites
Well, from my experience, people who race 125's are really good riders, some of them far better then the guys who ride around on 4 strokes.

The track itself has a lot to do with how well certain bikes go. For instance, 4 strokes do better then 2 strokes when it comes to building power, so going up hills is a killer for a 125 compared with a 450. Jumps that are right after slow corners are another issue for 125's because building power quick uses a lot more energy on a 125.

Honestly, you can't compare 125's and 450's, they are at complete opposite ends of the spectrum in terms of ease of use. The closest comparison is 125 and 250F because both bikes you need to shift and both bikes take time to build power.

This is not true. Have you ridden a new 250f? my new 11 can run the entire track in third and fourth gear. Its absolutely nothing like my 125. I feel much faster on my 125 but on the clock i'm not. I love riding it. I'm not faster on it. Just like in another thread changing clickers to adapt to one jump instead of just taking a different line, the 125 requires an outside line if theres a fast paced obstacle right after it. A lot of information is wrong there.

Share this post


Link to post
Share on other sites
This is not true. Have you ridden a new 250f? my new 11 can run the entire track in third and fourth gear. Its absolutely nothing like my 125. I feel much faster on my 125 but on the clock i'm not. I love riding it. I'm not faster on it. Just like in another thread changing clickers to adapt to one jump instead of just taking a different line, the 125 requires an outside line if theres a fast paced obstacle right after it. A lot of information is wrong there.

I agree with there being a lot of incorrect information in his posts.

Like you, I have a 06 YZ and a 10 EFI 250F. Love riding the 125 and use it as a practice bike. I feel faster on it and in some areas I am faster, but overall I am more consistent and faster on the 250F.

I think any ride who has not spent quality time on a 125 is missing valuable time that needs to be spent on a bike. They are imo the absolute most fun bikes to ride and will make you a much better rider when all is said and done.

Share this post


Link to post
Share on other sites
I agree with there being a lot of incorrect information in his posts.

Like you, I have a 06 YZ and a 10 EFI 250F. Love riding the 125 and use it as a practice bike. I feel faster on it and in some areas I am faster, but overall I am more consistent and faster on the 250F.

I think any ride who has not spent quality time on a 125 is missing valuable time that needs to be spent on a bike. They are imo the absolute most fun bikes to ride and will make you a much better rider when all is said and done.

I haven been to the track with both my bikes at the same time yet, but when I went shortly after getting the 125, and having an 07 250f, I actually rode the 125 more. The 11 is awsome in all ways, but the 125 is fun and gets you into great shape and helps you to pick the right smooth lines, not just the easy way out on the inside with the tourque pulling you out.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×