06 yz450f needs new plastic white piston? Top valve assembly

5 replies to this topic
  • Octanee

Posted August 20, 2013 - 01:17 PM


Hi guy, so basically my fork seals are done, no big deal but when I changed my 2 recoil? Rebound? Springs at the top of the forks, I noticed they were breaking, there's a bushing on them and it appeared the plastic holding the bushing is too small and so they both broke it away, I went to yamaha and they say they can only sell me the upper valve assembly, I don't need all that crap and it's expensive. Where can I buy some new ones? They are a white plastic kinda piston? Very top of forks when you unscrew the top of fork there.

I'm hoping to buy after market if I can thinking it will fix it, Imo I see what I have as a design flawed item. I'm at work so I don't have a pic of what I'm talking about, but I'm hopi g to be pointed in the right direction, thanks!,!

  • Octanee

Posted August 20, 2013 - 01:38 PM


It's apart of 12,36 in this pic but it doesn't actually have a item number, it's in the middle there between 13,37 and 14,38, thanks

  • grayracer513

Posted August 20, 2013 - 02:54 PM


Any KYB parts dealer will have these.  They are commonly called "free" pistons, or inner chamber pistons. 


Two sources are SMART Performance and Suspension Direct

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  • Octanee

Posted August 20, 2013 - 06:09 PM


Any KYB parts dealer will have these. They are commonly called "free" pistons, or inner chamber pistons.

Two sources are SMART Performance and Suspension Direct

thanks again greyracer, time and time your here helping others, keep up the great work and thanks! Greatly appreciated :)

any suggested things to-do to my forks "while their apart"? As in upgrades or such? Otherwise I'll be putting in the new pistons and a complete seal/ bushing set

  • grayracer513

Posted August 21, 2013 - 06:05 AM


Without tinkering with a revalve, not much needs doing.  The one thing I do recommend is drilling the free pistons.  That vents them to the outer chamber and helps prevent them from cracking.




When you order the pistons, be sure to ask for a pair of the seals that seal the piston to the shaft.

  • DaveJ

Posted August 28, 2013 - 08:17 AM


We have put both the aluminum and upgraded plastic units on eBay. Hope this helps.



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