It's Here...the 2010 YZ450F


1000 replies to this topic
  • grayracer513

Posted September 24, 2009 - 07:45 PM


The number of valves in the head has no bearing on reliability. The quality of the valves is another matter.

In order to get the same volume as the three intake valves two must open longer and farther.

That is also not true.


Read:

http://www.thumperta...857#post8599857

  • ProjectDIRT

Posted September 24, 2009 - 09:10 PM


yea just cause theres more does not mean that it flows more. lol if you knew about the 5 valve head you would know thats why the bike is hard to make power with. more isnt always a better thing.

  • mx730md

Posted September 25, 2009 - 04:06 AM


Images from MxDaD324 on VitalMX:

Posted Image
Posted Image
Posted Image
Posted Image
Posted Image
Posted Image
Posted Image


wow yamaha should ship the bikes with the gyt-r decals. it looks so much better without the two tone radiator shrouds. i think im going to start saving my pennys and hopefully next year about this time i can pick one up. it looks like drd pipe doesnt have a resonator chamber on it...

  • jcross312

Posted September 25, 2009 - 04:38 AM


Even if we assumed that Yamaha would want to use a unicam, the first reason is ,likely to be that Honda holds a patent on it.

No matter. The Unicam is technically inferior to the bucket tappet DOHC set up used in Yamaha and many other engines for several reasons. The Unicam uses rockers on the exhaust, and unless the designer places a bucket tappet over the valve on which a rocker arm acts, the rocker creates lateral loading on the valve guide that is not present with the DOHC set up. There are also more moving parts and wear points overall.

Apropos of the discussions on what was invented when, I recall seeing this same concept in some Japanese 4 cylinder or other, an Isuzu, possibly, about 10 years ago, so even it isn't new.


So the guides on a DOHC engine last longer. Thats good. I can see how the single cam engines do have more wear points. The main benefit still though is the weight.

Don't the patents expire or something. I remember honda used to have the patent on the "behind the fork" brake line. Then all bikes had them.

  • DPW

Posted September 25, 2009 - 04:45 AM


wow yamaha should ship the bikes with the gyt-r decals. it looks so much better without the two tone radiator shrouds. i think im going to start saving my pennys and hopefully next year about this time i can pick one up. it looks like drd pipe doesnt have a resonator chamber on it...



Posted Image


looks pretty nice huh? I'm thinking the same thing you are, '10 or '11 YZ450F fund is starting today..:busted:

  • Thumper38

Posted September 25, 2009 - 05:14 AM


That thing is beautiful I can't eait till mine comes in!!!

  • jcross312

Posted September 25, 2009 - 05:58 AM


Does it come with the radiator braces?

  • 02WR426Cali

Posted September 25, 2009 - 06:15 AM


I'm not sure if this has been mentioned or not but what about all the weight from the rider on the gas tank? It seems like there would be more weight for the tank to take on since it is further underneath the seat. Anyone know if they made the tank stronger so that it doesn't flex as much? Just curious

  • mx730md

Posted September 25, 2009 - 06:27 AM


I'm not sure if this has been mentioned or not but what about all the weight from the rider on the gas tank? It seems like there would be more weight for the tank to take on since it is further underneath the seat. Anyone know if they made the tank stronger so that it doesn't flex as much? Just curious


i dont know but the tank on my yz doesn't flex at all. not sure if it has changed but when i mount my seat the subframe looks like it take the majority of the weight . looking at the pictures the tank doesnt look to be any farther under the seat then before maybe 1 or 2 inchs at the max... cant wait till i can get one or at least throw a leg over one

2009 yz450f
Posted Image

2010 yz450f
Posted Image

  • grunkthump

Posted September 25, 2009 - 06:57 AM


Gray if Honda holds a patent on unicam WHY is KTM also using it??

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • grayracer513

Posted September 25, 2009 - 07:07 AM


Is KTM using it? I haven't paid much attention to them, but I thought they were SOHC engines, with rockers on both the intake and exhaust.

The newer 250F's are DOHC with rocker followers. Both these designs also promote valve guide wear.

  • ProjectDIRT

Posted September 25, 2009 - 07:37 AM


yea ktm is a standard sohc motor. and really a cam is only like a pound. not that much to save a honda head weights the same as my 5 valve.

  • ProjectDIRT

Posted September 25, 2009 - 07:38 AM


if your worried about weight i think there will be alot to loose from a pipe as the stock header looks to be stainless and the canister probably is a tank. replace with all ti stuff.

  • OUTERLIMITS

Posted September 25, 2009 - 07:40 AM


Is KTM using it? I haven't paid much attention to them, but I thought they were SOHC engines, with rockers on both the intake and exhaust.

The newer 250F's are DOHC with rocker followers. Both these designs also promote valve guide wear.


What would be the benefit of a DOHC head with rockers? Ease of valve adjustment? Just seems like extra parts. :busted:

  • Flyin Dub

Posted September 25, 2009 - 07:46 AM


Trying to read between the lines of the early ride reports. In the Transworld video P Foster makes it sound as though the bike doesn't drop into corners very easily. His tail end gets kicked out on two corner exits in a fashion that is odd for a rider of his skill level. MXA is pretty tight lipped about its handling, and most everything else about the bike for that matter. Cycle news gushes about its handling but criticizes its herky jerky power delivery and difficult starting.

  • Streets45

Posted September 25, 2009 - 08:01 AM


I'm looking forward to the MXA full review... i tend to believe they tell it like it is....

i really hope it starts easy... im sick of bikes that dont start.... ugh my clutch started goin out on my 250F and i didnt have the money to replace it, damn thing wouldnt hardly start

  • grayracer513

Posted September 25, 2009 - 08:15 AM


What would be the benefit of a DOHC head with rockers? Ease of valve adjustment?

Yes. Might be less expensive to manufacture, but that's hard to say.

Cycle news gushes about its handling but criticizes its ... difficult starting.

They didn't say it was hard to start, only that it wouldn't start from some random position. My '06 prefers to be started by pushing the piston up against compression, too. I feel certain they are describing the process incorrectly when they use the term "TDC".

  • LEMMON1

Posted September 25, 2009 - 08:26 AM


I do like the blue bikes. I've been given plenty of opportunity to like the others too, and I'll ride anything. I moonlighted at a dealership up here that sells everything but Red. I've been really tempted by a CRF, SX-F, and an RMZ, but I've been saving my nickles for the 2010 ever since the 2009 came out and wasn't what this is. I'm not 100% on it either, I'm waiting to see what people say a few months from now after gremlins do or don't show up.

I think that you are right on the money when you say that new bike owners are going to defend their purchase and their company. I do however believe that there is a difference between defending a product to protect your pride, and being loyal to a company because of a posative history with their products.

I own products from 4 different powersports manufacturers, including Polaris, Kawi, Yamaha, and a Honda. So I'm not totally biased.

I think that this forum is pretty honest about what the YZ450s have and have not been. Mine is the one that tries to rip your arms off and turns like a torpedo, but I do love it. Obviously I do not have a problem saying that I like Yamahas. And as long as they continue to make products that I feel good about, I'll continue to "bleed blue". I can tell you honestly and objectively what I like about them, what I don't, what they do well, what they don't, and what I like alot about KTMs, Kawis, Zuks, etc...

All things considered, it looks like a good year to like blue bikes.


what he said :busted:

  • ProjectDIRT

Posted September 25, 2009 - 08:29 AM


If you listen to the transworld one. He states that it doesnt fall over into ruts not that it doesn't drop into corners. And he says that you can put it where you want it. Yea and on a bike you can't keep the motor at tdc unless you have the plug out. And yea his back end does kick but I think its more on that corner and nothin else. But I could be wrong on that. But with more weight toward the middle the rear should be more planned. Its like rynos riding style that he teachs. Duck but body over the middle so you plant the bike more.

  • harrperf

Posted September 25, 2009 - 08:33 AM


Trying to read between the lines of the early ride reports. In the Transworld video P Foster makes it sound as though the bike doesn't drop into corners very easily. His tail end gets kicked out on two corner exits in a fashion that is odd for a rider of his skill level. MXA is pretty tight lipped about its handling, and most everything else about the bike for that matter. Cycle news gushes about its handling but criticizes its herky jerky power delivery and difficult starting.


I feel not only did he not say it hanlded poorly...but that you completely missed his analysis.

If you ride a 450 back to a two stroke...or a 250f even...you quickly realize a couple things about 450's. First and formost...they like to stay at the angle they are at. If it's straight up and down...it likes to stay straight up and down.

If it's leaned over...it likes to stay leaned over. This is what I call the gyro effect...and if you own a small gyro...you know that the force is no bullshit even with small amounts of mass.

The other feeling you get riding a 450 is that it "falls" into corners. That is NOT a good thing. What he means is when the bike is straight up and down...and you want to turn it....it first very slowly starts to lean...and then as the "top heavy" mass gets far enough over gravity takes over and it "falls" over to lean. You must stop this fall at some point or you will actually fall over...

It's like walkign with a 50 pound weight above you head and when it tilted small amounts off center your ok..but as soon as it gets too far over the leverage it has over you makes you "fall over".

A good way to iillustrate what falling over is...is to take you bike in the garage or driveway...laneway....whatever...and first grab it by the bars and try to flick it side to side while standing on a side. Then take off the subframe, exhausts, gas tank and seat...and flick it side to side with the radiators drained...it's MUCH MUCH easier to do...and the bike only flicks as far as you want it to. No inertia effects because the center of mass is now closer to the pivot point of leaning side to side.

I get the joy of riding two strokes....four strokes...both big and small week in and week out. And that would be my exact description of a current 450. It falls into corners....and does so slowly. I have to initiate a turn on a 450 WAY before I do on two strokes or 250f's.....as it takes time for it to "fall". It doesn't "flick" into corners!


The downfalls of bikes that have mass closer to pivot point...is the dont "stay" where put. A two stroke, leans quickly and easily...but also gets changed from this lean position easily. So a four stroke, once leaned over...stays there till you bring it up. A two stroke makes you keep it there. This can be hard to adjust to for many people. It almost makes your technique more important.

Anyways...that's my interpretation of his comments.

Regarding his Kick i the video...I watched that a couple times and thought two things:
Wow that looks horrible for yamaha!

He should have known better coming into that roller like he did! A local track here has a turn much like that where it ends over a roller...and if you allow the bike to compress at the end of the turn by not getting turned and upright early enough...hang on for a ride!





Related Content

Forums
Photo

Snake pit oct 30th by The Anvil


Dirt Bike   Dirt Bike Regional Discussion   California
  • Hot  293 replies
Forums
Photo

Is it worth it? (Cam and High compression piston) by macgi77


Dirt Bike   Make / Model Specific   Honda   CRF 150/230 F/L
  • Hot  36 replies
Forums
Photo

100 hrs on 2014 yz450f, shim valves or replace them? by ttr230rider6


Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • Hot  79 replies
Forums
Photo

Megabomb Fitment by 288yz450


Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 1 reply
Forums
Photo

Chubby dad, looking at bikes , First trip to the orange/black forum ! by Slow_ride


Dirt Bike   Make / Model Specific   KTM   250-530 EXC/MXC/SXC/XC-W/XCR-W (4-Strokes)
  • Hot  28 replies
 
x

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.