My 2008 Yz 450f Review


340 replies to this topic
  • 250f canuck

Posted August 01, 2007 - 07:39 AM

#21

I think that the quiet pipe is something that we will need to get use to riding with and tuning around. I did run my stock WR muffler open and loud for a little while and loved the power, but eventually I would need to pass sound check somewhere. I made an insert for it and imediatly the bottem end started hurting for power. I've done a bit of tweaking to the jetting (thank you TT:thumbsup: ) and my power is back and so is 90% of the response. A few leak jet changes should fix that also.

IMO jetting is your issue.

  • djtroy

Posted August 01, 2007 - 07:43 AM

#22

Now all I need is someone to tell me what works for them. I guess the bike is too new so I will have to be the guinea pig on this one.

  • rickallen124

Posted August 01, 2007 - 09:36 AM

#23

I would call Dubach Racing,since they have already tested the bike, Zip-Ty and White Brothers-since they run Yamaha's amatuer support and see what they say. The '07 DrD pipe will add two more hp to the '08 450 from dyno runs they have done. Between the three companies you should be able to find the solution. Best of luck and please report your findings as I'm trying to decide between the YZ450F and the CRF450

  • stroker

Posted August 01, 2007 - 10:46 AM

#24

Why not contact JD jetting and see if he has a kit yet, try to work with what you have first. Once it is correctly jetted (confirm with exhaust gas analyzer) and ride with the people you normally do, you will then get a feel for how much boost the bike really has, I too have been fooled into believeing that the quiet bike is slower, then you drag race to the next corner and learn it is not slow at all, just quiet!!!

seems silly to start chucking on a $400 (or more ) pipe, that often just makes more noise and only moves around the power, yet seldom gives any real benefit, when it may just require some tuning.

Good luck!

  • matts06yzf

Posted August 01, 2007 - 11:32 AM

#25

i cant find a dyno number to save my ass. Dr D. Has done them but I called and she said Doug and Mike wont be back until next thursday, they are at LL. I am really close to buying one but damnit man I need some reviews, might have to go green for 08

  • Ga450owner

Posted August 01, 2007 - 12:45 PM

#26

i cant find a dyno number to save my ass. Dr D. Has done them but I called and she said Doug and Mike wont be back until next thursday, they are at LL. I am really close to buying one but damnit man I need some reviews, might have to go green for 08



yea he is racing 40+ class there...

  • stoney55

Posted August 01, 2007 - 12:52 PM

#27

sucks to have to buy mods for a brand new bike unless your out for bling. My 07 is great, I rode the 06 and thought mine cornered easier. I looked at the 08 at the track last week and was not real impressed. I'll wait for 09. thanks for the review that is great info.

  • SC_Spode

Posted August 01, 2007 - 01:00 PM

#28

Langston rode the '08 this weekend and won the 2nd moto. He made the comment that the '08 turns better for him. What did they do to the '08 that would make it turn better than my '07? If its real and true, it would make me consider buying a '08 because my '07 does not turn that well either compared to the yellow and red bikes, IMHO>


What I heard was Yamaha "removed some material" from the frame to reduce the stiffness of the front end (built in some flex) and this has removed the push the 06-07's had.

From the website - "Steering head pipe and steering stem are 5mm shorter; lower forged triple steering clamp is lighter—for enhanced handling feel. Swingarm pivot stiffness is revised to complement front-end changes and further lighten and improve steering/handling."


Like the original writer said, it works for him - I'm guessing it must be real and not just ad hype.

:cheers:

  • djtroy

Posted August 01, 2007 - 02:38 PM

#29

What I heard was Yamaha "removed some material" from the frame to reduce the stiffness of the front end (built in some flex) and this has removed the push the 06-07's had.

From the website - "Steering head pipe and steering stem are 5mm shorter; lower forged triple steering clamp is lighter—for enhanced handling feel. Swingarm pivot stiffness is revised to complement front-end changes and further lighten and improve steering/handling."


Like the original writer said, it works for him - I'm guessing it must be real and not just ad hype.

:cheers:




No im not kidding this 08 not only corners good its amazing, I can rip into corners without the understeer and feeling it wont turn into the inside ruts like the 06/07

  • matts06yzf

Posted August 01, 2007 - 04:41 PM

#30

No im not kidding this 08 not only corners good its amazing, I can rip into corners without the understeer and feeling it wont turn into the inside ruts like the 06/07


Thats great but many have said the motor sucks, here and at the track. I was a lake sugartree sunday and a guy had an 08 he said felt really weak compared to his 06. I want one and have the money but damn the more I hear about a mellow engine sounds like I might go green. I reallyyyyyyyyyyyyyyyyyyyy want to stay with yamaha my 06 is bullet proof but people keep saying it feels like a 250. I am 6'4 and not a small dude and I need some ass. I have a race coming up and I want a 08 for it. But I have to get my suspension to enzo, yada yada before I race so I need to buy one but I am scared of a weak motor.

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  • djtroy

Posted August 01, 2007 - 06:38 PM

#31

Thats great but many have said the motor sucks, here and at the track. I was a lake sugartree sunday and a guy had an 08 he said felt really weak compared to his 06. I want one and have the money but damn the more I hear about a mellow engine sounds like I might go green. I reallyyyyyyyyyyyyyyyyyyyy want to stay with yamaha my 06 is bullet proof but people keep saying it feels like a 250. I am 6'4 and not a small dude and I need some ass. I have a race coming up and I want a 08 for it. But I have to get my suspension to enzo, yada yada before I race so I need to buy one but I am scared of a weak motor.



Suspension and cornering will be just fine for any race. The motor needs to be shifted and has no bottom end.
I am glad some other people agree with me. The other guy on here was calling me crazy for saying the motor sucked and had no low end. For some reason he thinks his is perfect. Then again he works at a Yamaha dealership so maybe hes tainted.

Wait I work at one too , but ill tell it like it is. :prof:

  • hey guy

Posted August 02, 2007 - 08:57 PM

#32

I got a 2007 YZ450F this weekend and my buddy got a 2008. After we broke in our bikes, we switched bikes for a while, right away I noticed the lack of bottom end on the 2008. It was a huge difference, I could really feel the lack of power down low, even my buddy said the same thing. The 2008 is still a great bike, I think the pipe is just restricting it too much.

  • Mutu

Posted August 02, 2007 - 11:26 PM

#33

I got a 2007 YZ450F this weekend and my buddy got a 2008. After we broke in our bikes, we switched bikes for a while, right away I noticed the lack of bottom end on the 2008. It was a huge difference, I could really feel the lack of power down low, even my buddy said the same thing. The 2008 is still a great bike, I think the pipe is just restricting it too much.

Welcome to noise control.....

  • Huckster

Posted August 03, 2007 - 03:09 AM

#34

I got a 2007 YZ450F this weekend and my buddy got a 2008. After we broke in our bikes, we switched bikes for a while, right away I noticed the lack of bottom end on the 2008. It was a huge difference, I could really feel the lack of power down low, even my buddy said the same thing. The 2008 is still a great bike, I think the pipe is just restricting it too much.


Did the '08 turn better?

  • yamasaki

Posted August 03, 2007 - 04:27 AM

#35

Did the '08 turn better?


yeah, interested in that too.

  • stroker

Posted August 03, 2007 - 11:55 AM

#36

maybe the reason the manufacturers are resisting the call to build a 350cc bike is because they have already built the future models meeting 2010 emissions and know that we will need a 450 (or bigger) to give us the boost we want with the future sound and pollution regs??

  • djtroy

Posted August 03, 2007 - 05:01 PM

#37

yeah, interested in that too.



Trust me IT TURNS SICK!!!!

The header pipe is bigger and the silencer is shorter. I suppose the lack of back pressure is whast killing the bottom end on this bike.

Pipe manufacturers are gonna have a hayday. I wonder if people will scrap the quiet short and go with a louder full size silencer.

  • Ga426owner

Posted August 03, 2007 - 05:39 PM

#38

Trust me IT TURNS SICK!!!!

The header pipe is bigger and the silencer is shorter. I suppose the lack of back pressure is whast killing the bottom end on this bike.

Pipe manufacturers are gonna have a hayday. I wonder if people will scrap the quiet short and go with a louder full size silencer.



that is guaranteed.........they are already working on them but they are testing for lower noise ....regulations

  • grayracer513

Posted August 03, 2007 - 08:54 PM

#39

I suppose the lack of back pressure is whast killing the bottom end on this bike.

It would be more likely that the additional back pressure is doing that. It seems you have based your assumption that there is less restriction in the new exhaust on a larger header diameter and a shorter silencer of the same internal design as the '07. The '08 muffler is not at all the same.

http://www.motocross...F3E7ECC2A3CD20C

Besides, it doesn't work like that. The ongoing myth that back pressure created by any sort of exhaust restriction is of some benefit to a 4-stroke continues to amuse me.

  • Climber

Posted August 04, 2007 - 06:00 AM

#40

It would be more likely that the additional back pressure is doing that. It seems you have based your assumption that there is less restriction in the new exhaust on a larger header diameter and a shorter silencer of the same internal design as the '07. The '08 muffler is not at all the same.

http://www.motocross...F3E7ECC2A3CD20C

Besides, it doesn't work like that. The ongoing myth that back pressure created by any sort of exhaust restriction is of some benefit to a 4-stroke continues to amuse me.



This is true. Lowend is more a function of enertia scavenging that creates a ram effect during the overlap (exhaust and intake) built into the cam. That is why you can run a loger duration cam, if the lobe centers are closer together, and still have decent lowend. As well, you get the cranking pressure back that you loose with a wider lobe separation, of the same duration. It all comes down to the speed of the pulse and the length of the exhaust system. A larger header will not help the pulse to move faster. But, I'm guessing that Yamaha thought all this out. The exhast system rely begins at the air cleaner and needs to be tuned accordingly. It is interesting to note that, in the Auto world, the straight through, glasspack style mufflers, don't work as well. The turbo, chamber, style mufflers flow much better. I think and hope the the new style of muffler catches on.

One thing I noticed in this thread is that the people who complained about the power of the 08s were at a lower altitude than those who liked it and are at higher altitudes. Typical Yamaha lean jetting. Just a thought.





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