2003 YZ 450 Horsepower / Torque

8 replies to this topic

Posted April 03, 2008 - 09:58 AM


I`m wondering if anyone knows the exact HP /Torque numbers for a 2003 YZ 450 ? I am just curious thanks for your replies.......

  • grayracer513

Posted April 03, 2008 - 03:04 PM


No, because no two dynos ever run up the same numbers. A good '03 produces about 47-48.

  • 02YZFkid

Posted April 07, 2008 - 09:31 AM


I have been wondering the same exact thing. My cousin has a 03 with some minor mods like an exhaust, heavier flywheel, and we think it has the Zip Ty carb mod, and it runs really strong. I just bought an 07 as a leftover last november, and we were wondering how the power numbers compare. My 07 is completely stock, an dits bottom end feels lagging compared to his, on top they feel similar... hard to judge with the different tranny's in them though.

Gray, do you know how the power numbers stack up from 03 to 07? What would you expect the 03 to produce with the simple mods listed above in comparison ot my 07?


  • grayracer513

Posted April 07, 2008 - 09:53 AM


The flywheel changes nothing as to HP output, for one thing.

The best otherwise stock '03 with a pipe that I've seen produced 49 HP. A stone stock '06 cranked out 49.75 on Eddie Sisnero's dyno at 5000 feet. The '07 has about a half horse more at peak than the '06 did, and the '08 is close to 52.

The difference is in the way that the low and mid range on the later bikes is delivered. When the '06 first came out, it was panned for its "soft" low end power. The '07 had the power curve moved even farther up the rev range yet. These changes made the bike much more controllable compared to the explosive low/mid range of the '03, and despite the impression that the bike is down on power, people found themselves turning faster lap times, and riding longer with less fatigue.

If you take both bikes out on the pavement, you will discover something. Not one person in ten who rides the two would fail to see the '03 as the more powerful of the two, and yet, when run side by side with an '06 or '07, the two bikes will run dead even until the two get up in third gear, where the later bike will start to pull away. The "soft" power of the newer YZF's is one of the most masterfully executed illusions of all time.

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  • 02YZFkid

Posted April 07, 2008 - 10:24 AM


Yea I know the fylwheel wont effect the HP numbers, but I think it does minimize the "hit" on the bottom end. It makes the power feel like it comes on a little smoother. So with the mods he has will they run just about dead even?
How would a Dr. D pipe and the Zip Ty carb mod come together on the 07 to effect peak HP figures? How would they improve the "power under the curve" to match the power the 03 seems to have down low.

Thanks again! You are a huge help!

  • John407

Posted April 07, 2008 - 10:35 AM


Gray, I'm you are right about the HP illusion. I had the chance to ride a stock '08 back to back with my '03. It was on a pretty rough sand track. I was actually pleasantly suprised by the '08 HP. After reading and listening to all the magazines I though it would be a dog. It wasn't, I thought it had pretty good power, but to find out it has 4 hp more than my '03 is hard to believe. Maybe they used bigger horses in '03 than they do now? :thumbsup:

The biggest difference that I could feel? It feels as light on the track as my '04 KXF 250 does, way lighter than my '03.

  • grayracer513

Posted April 07, 2008 - 11:16 AM


So with the mods he has will they run just about dead even?

Actually, my son's '06 (stock w/DRD SS pipe) pretty much thrashed my '03 (FMF Ti 4) in the big gears.

How would a Dr. D pipe and the Zip Ty carb mod come together on the 07 to effect peak HP figures? How would they improve the "power under the curve" to match the power the 03 seems to have down low.

The Zip-Ty mod is more a matter of sharpening the overall throttle response than peak power.

The DRD pipe on our '06's did exactly that; add power under peak, making the lower end stronger. But the power is still much more smoothly delivered and usable than that of an '03, even with a really heavy flywheel.

  • chase1873

Posted April 07, 2008 - 12:49 PM


Hi, im the one with the 03' 450 that my buddy is talking about above. I have the white bros R4 pipe, a GYTR flywheel, and i confirmed the Zip Ty mod also. does any one know wat numbers it should be putting out?

  • grayracer513

Posted April 07, 2008 - 01:09 PM


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