'03 yz450f fork flexing question.

9 replies to this topic
  • yamasaki

Posted August 15, 2005 - 01:27 PM


so, i've been doing some research on the '03 yz450f. As far as i can tell from reading up on articles that talk about the 46mm forks, the main drawback seems to be the fact that they were "flexing", which is why yami bumped them up to 48mm (yes, along with the slicker internal coating,etc, but the main problem was 'flex').

my question is, do you guys ever notice this "flex" or is that only something you need to worry about if you're riding around at mx nationals top 40 paces?

  • BigDeSto53

Posted August 15, 2005 - 01:37 PM


Forks are FINE!! I haven't notice any flexing on mine, if they are i don't feel it!

  • kmier

Posted August 15, 2005 - 02:33 PM


Can you say Bold New Graphics?
There may be some truth to the flex, probably not, just more sales hype to get those new bikes off dealer floors.
Are you old enough to remember right side up forks? Then they went upside down. Less flex was supposed to be their strong point, they were harked as the next big thing in mx. Then years later some of the manufacturere went back to right side up forks, they said the upside down forks were too rigid and had too much internal friction, some flex, not too much, was designed in, this was good for control and rider fatigue. The reviews were good, we were in for another revolution in mx technology. Yea, right.
HaVE you bought the bike yet?

  • yamasaki

Posted August 15, 2005 - 03:04 PM


not yet, but i'm ready. i have a meeting set up for the 27th with the seller.

Thats what i figured about the "flex", just wanted to get some feedback. I spoke with 2 other guys with '03 450f's at the track this weekend, and they had nothing but great things to say about the bike. They were both A/B riders.

I'm probably a lower to mid-level C rider.

  • Ga426owner

Posted August 16, 2005 - 05:30 AM


It is not an issue unless you are a top 5 Pro rider.........

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

Posted August 16, 2005 - 07:55 AM


Technically, they do flex more than the 48's. Will it make any difference to your riding or mine? I seriously doubt it, and if it did, neither of us would notice.

But along with the extra rigidity came internal damping improvements and an increased oil/air volume, which helped the fork action noticeably. The 48's are a better fork, but by a small margin, and the 46's can be worked with and turn out to perform very nicely.

  • John407

Posted August 16, 2005 - 12:48 PM


I've never noticed the fork flex on my 03 450, but then I don't really think I felt the flex on any of my older bikes either. I did run a KLX 365 with '89 KX right side up forks and they seem more plush than any of the up side down forks I've ridden since.

Grayracer, you mention working on the 03's forks to improve their performance. Do you have any suggestions that can be done at home or is sending it out to a shop the only way?
One more question, does a front sprocket from a YZ250F fit a 450F? I probably should know but I don't. Thanks

  • grayracer513

Posted August 16, 2005 - 01:47 PM


A good revalve and sub tanks. And Dexron III ATF.

I made my own tank setup. Take a Look

  • yamasaki

Posted August 16, 2005 - 04:37 PM


A good revalve and sub tanks. And Dexron III ATF.

I made my own tank setup. Take a Look

wow! :eek: :D :eek: :eek: :D

very nice job on that sub-tank.

ok, so, i'm suspension ignorant.. what does it do exactly???? :D

  • Ray450

Posted August 17, 2005 - 09:03 AM


Take a KDX 200 out on an arena cross style track, and you can detect what flex is. I had a 03 450, but used my 200 to practice and run sweeper laps on (I was an official in TCCRA). I also used it to ride the B practice with my buddies at Village Creek M/X (I rode A practice on my 450). It was a blast, but probably not real smart. I had a 04 YZ 250 and a 450 now with the 48s. The overall design is better, but the actual performance gain is small. The 46s had a lot of years to get right. If anything, the reduction of flex is a bad thing for 95% of the riders out there. I wouldn't worry about it. Top Pros actually bend their frames out of tolerances after just a few races, I'm pretty sure most of us can't do that if we wanted to (without crashing in the process anyway).

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