2003 YZ 450 fast?


15 replies to this topic
  • xr250ryder

Posted August 19, 2007 - 09:37 AM

#1

Ok, I've taken my time to search through the forums and I didn't exactly find what I was looking for. So I'm going to ask. Everywhere I look people keep commenting on how fast the 2003 yz450s are. Why are they so fast, are they really that fast, and how? I have a 2005 wr450 it has a bit of getup and go, but I would like to make it comparable to a 2003 since they are 'supposedly' the fastest of the 4-stroke yz's. Could anybody tell me the difference(s) between the 2003 and lets say 2005 yz 450? Thanks in advance.

  • grayracer513

Posted August 19, 2007 - 10:10 AM

#2

It can't really be done, as a practical matter, for one thing, because of the WR's vastly heavier flywheel. And anyway, it's not so much a matter of absolute horse power as the way it's delivered. The '06 YZ450 has a significant amount more horse power than the '03 does, but the off-idle torque response of the '03 is so unrestrained and immediate that almost everyone thinks it's the other way around. Most of this difference is accomplished through better management of the advance curve, although the '06 cams are timed slightly differently. On pavement, both bikes accelerate evenly until 4th gear, at which time the '06 starts to assert itself.

Buy an '03-'05 YZ450 exhaust cam, do the air box, throttle stop, and grey wire mods, and add a decent, low noise, performance exhaust like an FMF Q, and you'll have a much more powerful ride than now. You can add a Vortex advance box later, if you want to tweak it more

  • xr250ryder

Posted August 19, 2007 - 11:09 AM

#3

Ok, I've done the air box mod, Grey wire mod, and the throttle stop. I was planning on buying a FMF Powercore for it also. Then once that is done I was thinking yz exhaust cam, and then if i wanted more power i'd throw on a MegaBomb. Then id prob ship my carb off to ZipTy somewhere in there. Is there any difference between the wr cdi unit and the yz? Besides the grey wire of course. I can probably pick one up on ebay if it made any bit of a difference.
I think that will put me in the power range that I was looking for.

  • grayracer513

Posted August 19, 2007 - 11:24 AM

#4

Is there any difference between the wr cdi unit and the yz?

I don't know how compatible it would be with the rest of the system. You might check on the WR forum to see if any of the guys over there have experimented with that.

  • kawirider

Posted August 19, 2007 - 03:19 PM

#5

I have an '03 YZ450F. Like grey said, its off-idle torque is like an explosion. So yes it hits hard like a 2 stroke.....but you don't really want the hit to the degree that the '03 has it. I went from a '00 KX125 to my 450 and it was too big a jump. I know my skills have probably been held back because of how difficult it can be to ride at times.

I mean riding singletrack fast on a '03 450F is so freakin hair raising that it can bite anybody hard. For me the bike has about 2 speeds.

1. So slow you don't have to stand up
2. So fast your about to crash

After having it for almost two years now I have gotten used to it......and I'm sure a pro or any other rider significantly better than me would find it a lot more ridable but, to me its a lot more than you want to tackle.

I guess one thing that is good about my bike that has helped me become a better rider is the fact that this bike won't let you halfway anything. I learned to attack hillclimbs and corners like my life depended upon it. If you want a more aggresive bike, and don't feel like spending lots of $ on mods, just sell your WR and get a YZ450F. WRs tend to be worth more than YZs anyways so you shouldn't have a problem doing that unless yours is clapped out.

  • xr250ryder

Posted August 19, 2007 - 03:51 PM

#6

To tell you the truth the only reason I haven't sold it and bought one is the 4-speed and the fact that I like the head-light. If the yz was a 5-speed this topic wouldn't exist.:eek:

  • OrangeYZ

Posted August 19, 2007 - 05:25 PM

#7

YZF's are 5-speeds now. 06 and 07 I am sure of, and maybe the 05 (maybe not)

  • grayracer513

Posted August 19, 2007 - 07:05 PM

#8

1998-2002: 5 speed
2003-2005: 4 speed
2006 up: 5 speed

The topic would exist regardless, as it does in all the other MX four stroke forums. MX bikes have close ratio transmissions that hinder their performance as woods bikes to some extent, regardless of how many gears they have.

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  • kawirider

Posted August 19, 2007 - 07:13 PM

#9

Dude I went from a 6 speed to a 4 speed, and the only time I was ever hunting for another gear is when I am doing 80ish. Maybe in washington the trails are different but here in AL I never need another gear. Besides, 95% of the time I am in 2nd & 3rd anyways so there is really no need for the 5th gear.

More power = less gears needed.

Honda Civic? Yeah you really need at least 5 and want 6.
My friends '70 Chevelle SS w/crate 502? Anything more than his 4 speed would be suicide.

If 1st gear on a mx 450 is too tall for you......ride faster :)

  • JSanfilippo

Posted August 19, 2007 - 07:58 PM

#10

Dude I went from a 6 speed to a 4 speed, and the only time I was ever hunting for another gear is when I am doing 80ish.


I've ridden close ratio big bores and I wouldn't trade my WR tranny for anything.

Realistically for the kinda riding I do, I really only need 3 gears (2-4) :busted:

  • xr250ryder

Posted August 19, 2007 - 09:00 PM

#11

Realistically for the kinda riding I do, I really only need 3 gears (2-4) :busted:


I agree, but I don't wanna fork out the extra cash to put a wide-ratio in the 03 when I already have it. I do like the top end because I ride on the road, and at 80 I will be looking for 5th.

  • JSanfilippo

Posted August 20, 2007 - 12:16 AM

#12

I agree, but I don't wanna fork out the extra cash to put a wide-ratio in the 03 when I already have it. I do like the top end because I ride on the road, and at 80 I will be looking for 5th.


The fifth is nice:worthy:

especially when your're in 4th and your 250 2 smoke buddies are tapped out in 5th, you just click up one more time and walk away from them:busted: :thumbsup: :applause: :worthy:

  • xr250ryder

Posted August 20, 2007 - 09:18 AM

#13

Yep, been there done that. I loved the look on his face "i had it pinned and you kept pulling away" lolz. I think ill just try to convert to a 05 yz. Thanks for the help guys.

  • crustyrdr

Posted May 17, 2011 - 06:27 PM

#14

I have a 03 yz450 put a 13.5 race piston open air intake full yoshi exhast it hits like a freight train I can keep up with my skill level on any bike a old gun will kill u like a new 1 I am 51 and still riding mx and even win races now and then also a track groomer living the life

  • Bobbed06

Posted May 17, 2011 - 08:41 PM

#15

I have a 03 yz450 put a 13.5 race piston open air intake full yoshi exhast it hits like a freight train I can keep up with my skill level on any bike a old gun will kill u like a new 1 I am 51 and still riding mx and even win races now and then also a track groomer living the life


What track to do maintain? I spent some time in Florida riding in Croom, Orlando Motocross World, and Hardrock MX park... I plan on riding all of these places again soon.

  • crustyrdr

Posted May 18, 2011 - 05:23 PM

#16

Ior was grooming thundercross down in okeechobee great track its about 2 miles long closest thing 2 a pro out door track u can find in fl I am rehaping now after a nasty crash a bike landed on my back after a 60ft tabletop on my warm up lap it was ugly compound fractuce rt arm 2 surgeries later it coming back ok have not been in the dirt in months that really sucks few mor wks I will doing some easy ridin cann't wait u should try pax track in bunell or bostwick in jacksonville both great tracks email me @ jkfrankyz@gmail.com when u r in fl and we'll ride





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