250f for mx and trails

[yzkx]

Hey guys i'm new to thumpertalk but not to dirt bikes. Im buying a new 2012 bike and cant decide between the yz250f and kx250f. I read that the kxf250 was putting out 39 hp, but putting out that much hp wouldnt that affect the reliability? I know yamaha is the best at being reliable which is why Im liking the idea. Also what about the handling of each bike? I havent read any test on either bike so im not sure about which would be best in this category, all i know is that the kxf is heavier than the yzf, im kind of short at 5'6'' so whichever bike caters to a smaller rider is a plus. Also what about the carb vs dfi, does dfi really make a bike start easier and that much better? So which would you choose if you were in my shoes, yz or kx. The bike will be used more for mx than trails, only the occasional ride through the trails with friends

[tye1138]

I only know about MX, so someone will have to answer your question about the trails.

I've ridden the carbureted KX250F's and many YZ250F's. I really like the YZ because the suspension is plush and handles like a dream. The older kawasaki's did not handle that well, but used their motor as the big advantage over their rivals. The YZ motor ain't the best lump power wise, but it is tame and the most reliable lump you'll find. Will it still go catastrophic on ya? Sure, if you abuse it and don't do any valve checks. But they ARE super reliable, much more then the KX's for sure.

I mean the downside is, the YZ is super out of date. I also hate the stock carb, I think its an absolute piece of junk. But its so easy to find parts and so many people know about them, that the negatives don't outweigh the positives. At the same time, comparing 2012 bikes, the KX is the one to get, hands down.

So if you're gonna buy used, go for the YZ, if you're gonna by new KX all the way!

[infamy]

just pick your favorite color and

[Theeebalz]

was the kx's hp rating from the crank or from the wheel? from the crank 39 is normal (a 125 2st puts about that out AT THE CRANK)

[Theeebalz]

and really 250f's are pretty good on trails, just cant lug them really slowly for to long or the radiators will start to overheat.

[yzkx]

was the kx's hp rating from the crank or from the wheel? from the crank 39 is normal (a 125 2st puts about that out AT THE CRANK)

it was put on a dyno so probably wheel, unless im wrong

[yzkx]

just pick your favorite color and

I dont have a favorite color ?

[yzkx]

I only know about MX, so someone will have to answer your question about the trails.

I've ridden the carbureted KX250F's and many YZ250F's. I really like the YZ because the suspension is plush and handles like a dream. The older kawasaki's did not handle that well, but used their motor as the big advantage over their rivals. The YZ motor ain't the best lump power wise, but it is tame and the most reliable lump you'll find. Will it still go catastrophic on ya? Sure, if you abuse it and don't do any valve checks. But they ARE super reliable, much more then the KX's for sure.

I mean the downside is, the YZ is super out of date. I also hate the stock carb, I think its an absolute piece of junk. But its so easy to find parts and so many people know about them, that the negatives don't outweigh the positives. At the same time, comparing 2012 bikes, the KX is the one to get, hands down.

So if you're gonna buy used, go for the YZ, if you're gonna by new KX all the way!

http://www.tokyomods.com/carburetion/carburetion.html I saw these guys sell stuff for the carb, would that make it better? Why is it that you think that the kx isnt up to par with the yz in terms of reliability? Did you see some let go? Whenever i go to the track all i see is a sea of green. So you'd choose power over handling? Wouldnt it be easier though to get a bike to put out more power than make it handle better?

[Theeebalz]

ride the bike a few times before you do any major mods, you might be thoroughly surprised!

[yzkx]

which bike would you say is better yammablue22? Isnt the carb mod just jetting so you dont have to mess with it? Just the fuel screw.

[tye1138]

I saw these guys sell stuff for the carb, would that make it better? Why is it that you think that the kx isnt up to par with the yz in terms of reliability? Did you see some let go? Whenever i go to the track all i see is a sea of green. So you'd choose power over handling? Wouldnt it be easier though to get a bike to put out more power than make it handle better?

Yea, you can modify the carb no problem, but its just one more piece of the puzzle.

I use to hang out at a shop, they sadly just closed. But during my two years of time there, twice a week sometimes three times a week, I learned a lot about which bikes are the most reliable. The problem with the KX's is the simple fact, they are rev-kings, they LOVE to be revved and reward the rider with more power at the top of the RPM curve. Look a the YZ and most of its power is gone about 2000 RPM before the KX even starts its major power pull. That's a HUGE difference in reliability, astronomical! We too live in a sea of green as Pro Circuit is not to far away from the majority of the tracks down here. Both the Kawasaki and Suzuki 250f's have problems and we would see them in droves at the shop for catastrophic motor failures.

The YZ is the defacto best all-around motocross bike on the market, hands down. It does a lot of things right and it does not so many things wrong, which is why Yamaha have chosen time and time again not to update it, why mess with a good thing? So yea, I'd buy a YZ if I didn't care about going fast and riding motocross. But when it comes to motocross, there is no doubt, the 2012 KX250F is the best bike on the market, hands down, period. It blows the competition out of the water with its SFF, brilliant fueling system, gobs of power and chassis to die for. Yea, the breaks suck, yea the suspension is stiff off the showroom, but nobody is gonna ride one stock anyway.

Good handling for recreational riders is not a difficult thing. The problem is, most of the manufacturers don't want to build recreational MX bikes because the test riders would pan them. So they build bikes which can be raced out of the box and in some ways that hurts them. Its super hard to get plushness out of a fork/shock which have to be stiff for boost off jump faces, etc. Believe it or not, building a fast motor is tricky because you don't wanna do what Kawasaki does, which is raise the RPM to get power through cam profile changes. I mean ANYONE can do that, I can take a stock YZ motor, change the cam timing to be more radical/aggressive and probably get 50hp out of it at 15,000 RPM! It won't run for long at that RPM, maybe a few laps, but man, you'd have a 50hp YZ! heh ?

All of that to say, chassis setup is by far the most difficult thing, rake/trail/offset/wheelbase/ride height, all of that plays a MUCH bigger role then people think and it differentiates the great handling machines like the YZ and RM with the rest of the pack. Motors and suspension are actually not that difficult, pretty straight forward. Get the chassis right and everything else is just buttah!

[yzkx]

well i dont plan on going pro, i just like riding and racing for fun, its mostly mx that i do like i said trails every once in a while. What did you mean one more piece of the puzzle? I thought for 2012 yamaha made some changes to the engine and carb to help with top power. Also wouldnt, problems arise more because of the owners? Personally I maintain my bikes to the max, oil change every 5-10 hours, air filter every two rides, plus i buy the stainless steel oil filters so every time i change the oil i clean the filter. I also think there are more kxf's being sold than yz's. Like i said my local track is always full of them. So if there are more being bought there would be more with problems if that makes sense. i had an 08 honda before but i could never get the jetting right, i would try coming out of a turn and it would bog, which made me lose a lot of time. People always told me the honda was one of the least reliable bikes every made, personally i never had one problem the 70-100 hours that i owned it, heck the valves didnt even move, and i was not gentle to this bike, I would hit the limiter sometimes because i was to lazy to shift up, ive learned more since then to stay more in the middle and not let the engine rev to high. They both sound like great bikes, my friends own kxf's (09's) and havent had a problem with them(they race them as well), my one friend that has a yzf 09 as well hasnt had a problem but everyone who rides it say it feels underpowered compared to the kx and crf. For 2012 they made the changes on the yz which is pretty much the only reason i still consider it http://www.yamaha-motor.com/sport/products/modelfeatures/12/0/features.aspx

[tye1138]

Yes, the 2012 is suppose to be better, but the carb problems are not related to power, they're more related to the issues you talked about, bogging and generally not working properly even after repeated re-builds. I've worked on many YZF's and I absolutely hate that carb because you spend a great deal of time making sure its right and it never gets to the level you want it to be.

Hondas have a single cam, rocker arm system that works well when it works. When it doesn't work, the clamshell style valve retaining collets fail and a valve drops into the cylinder unexpectedly... woops. Its a VERY common issue with Hondas, seen it on bikes that were maintained religiously and even new bikes. You never want a beater high-hour Honda CRF, I'd rather not ride then have that as my only bike.

CRFs, KXF's, RMZ's, they will run 80 - 100 hours without much work done. After 100 hours, you really need to start thinking about changing out the piston and rings. At 100 hours, I'd also totally re-build the top end with new valve guides, new valve seats and maybe valves depending on how bad they are. The YZF's on the other hand, they seem to run to about 200 hours before they need any major service, that again is because the rev limit is lower on them, so they just don't get the same amount of wear. Its great you do oil changes and filter changes so much, but honestly its all about motor abuse on track that kills them.

There is a big difference between the riders out here and in most other parts of the country. Most of the people who ride motocross here, are racers and they abuse the living crap out of their machines. So when I see problems, its mostly because they were on the rev limiter constantly, like 5 times a lap or more, just to get that extra ounce of power. I have seen plenty of people go home from a blown motor in my few months of riding, its pretty common place.

I guess my point is; if you arn't anywhere near the limit of the machine, it really doesn't make a difference what you buy.

[yzkx]

Yes, the 2012 is suppose to be better, but the carb problems are not related to power, they're more related to the issues you talked about, bogging and generally not working properly even after repeated re-builds. I've worked on many YZF's and I absolutely hate that carb because you spend a great deal of time making sure its right and it never gets to the level you want it to be.

Hondas have a single cam, rocker arm system that works well when it works. When it doesn't work, the clamshell style valve retaining collets fail and a valve drops into the cylinder unexpectedly... woops. Its a VERY common issue with Hondas, seen it on bikes that were maintained religiously and even new bikes. You never want a beater high-hour Honda CRF, I'd rather not ride then have that as my only bike.

CRFs, KXF's, RMZ's, they will run 80 - 100 hours without much work done. After 100 hours, you really need to start thinking about changing out the piston and rings. At 100 hours, I'd also totally re-build the top end with new valve guides, new valve seats and maybe valves depending on how bad they are. The YZF's on the other hand, they seem to run to about 200 hours before they need any major service, that again is because the rev limit is lower on them, so they just don't get the same amount of wear. Its great you do oil changes and filter changes so much, but honestly its all about motor abuse on track that kills them.

There is a big difference between the riders out here and in most other parts of the country. Most of the people who ride motocross here, are racers and they abuse the living crap out of their machines. So when I see problems, its mostly because they were on the rev limiter constantly, like 5 times a lap or more, just to get that extra ounce of power. I have seen plenty of people go home from a blown motor in my few months of riding, its pretty common place.

I guess my point is; if you arn't anywhere near the limit of the machine, it really doesn't make a difference what you buy.

Awesome to hear ya i try to stay away from the limiter, id rather shift up, if i wanted to rev the crap out of a bike i would have bought a 2 stroke right! Ya after 100 hours for sure id send it to a shop to have the top end rebuilt. Ya like you said hondas are notorious for having problems, i never did so i cant say anything bad about them, some of my friends though have sent their bikes to the shop more times then theyve ridden it . Im with you on that carbs are kind of a pain in the butt to get good, ive owned 2 and 4 strokes, i never could get them to the point where they didnt bog. Which is where efi helps out a ton. Plus i hear efi helps with starting, is that true?

[Theeebalz]

which bike would you say is better yammablue22? Isnt the carb mod just jetting so you dont have to mess with it? Just the fuel screw.

my trust lies with yamaha because i've never had a major meltdown with any of their bikes (street bikes scooters dirt etc) but thats just me! if you ask my wishlist honestno money limit opinion? i'd tell you to get a 2stroke! cheaper when stuff takes a plop in the portajohn. something like a ktm 200/300xc sx xcw . suzuki makes pretty good bikes (fourstrokes) and i haven't heard about to many problems with them except around the 2004 era... hondas are great bikes if you have the money for the maint (olderones) yamaha's i've only seen valve problems from the earlier 250f's...

basically if you maintain any of these bikes they will all treat you well. if your not good with normal maint then go for something known for reliability.

and carbs jetting are all inside the carb, you pull it apart you have a main a leak and an idle, other various ones too but not as important.

[yzkx]

I didnt really like the 2 stroke when i owned it. Lots of vibration and i had to rev the piss out of it, plus it was a lot harder to get traction.

[tye1138]

ive owned 2 and 4 strokes, i never could get them to the point where they didnt bog. Which is where efi helps out a ton. Plus i hear efi helps with starting, is that true?

Well, bogging on a 4 stroke is very different then bogging on a 2 stroke. 4 stroke carbs are actually much more complex then 2 stroke carb's and they require quite a lot of work, even aftermarket parts, to get right. Thats why I refuse to own 4 strokes, to me the only "asset" they have is more grip due to the power curve, which makes them lazier to ride.

EFI does help with starting especially after a crash because you don't empty out the float, so the thing should start pretty quick. I have not crashed an EFI bike hard enough to give you a definitive answer. But all of my friends who own 4 strokes have spent what seems like an eternity on the side of tracks, trying to get their carbureted machines started. I can only sit and laugh, every 2 stroke I've ridden has started within a kick or two after crashed. The last thing you want to do as a rider is to kick that bloody 4 stroke after you crash.

God bless 2 strokes.

I didnt really like the 2 stroke when i owned it. Lots of vibration and i had to rev the piss out of it, plus it was a lot harder to get traction.

I think thats funny, the last thing I think about is how much vibration I feel when riding. Ohh and the grip level, meh... I kinda like not having a lot of grip, makes you work harder and that promotes better skill. ?

[yzkx]

ya ive crashed a couple of times and the bike shut off, man it was harder to start than cold! You know i never really thought about it either(vibration) until i got my 250f and tryed out a 2 stroke again, what a difference, i guess really its just getting used to it. Im a novice racer so i want the most traction possible! I would like to go back to 2 stroke, but i dont know it just seems like it'd be harder from already owning a 4 stroke. At 5'6'' and 130 pounds sometimes my 08 used to feel like a pig, which made me want to make the switch again, but all that traction and low end power makes me not want to give it up.

[tye1138]

ya ive crashed a couple of times and the bike shut off, man it was harder to start than cold! You know i never really thought about it either(vibration) until i got my 250f and tryed out a 2 stroke again, what a difference, i guess really its just getting used to it. Im a novice racer so i want the most traction possible! I would like to go back to 2 stroke, but i dont know it just seems like it'd be harder from already owning a 4 stroke. At 5'6'' and 130 pounds sometimes my 08 used to feel like a pig, which made me want to make the switch again, but all that traction and low end power makes me not want to give it up.

Yea, yea, I hear the racing argument all the time, but honestly a 2 stroke will make you a better rider as you'll be forced to learn how to ride without perfect traction, which means in good traction situations you'll go that much quicker! ?

Meh, this isn't a 2 stroke vs 4 stroke thread, sorry I didn't mean to bring it up.

Moving on!

[Theeebalz]

what he said is true you know... ride a four stroke for a while, you get tired of the predictability of it...