Fork seals

I am going to change the fork seals in a 03 yz450 I recently purchased. I have looked evrywhere to find the diameter of the forks to get the propper seal driver. What is the diameter? Do any of you have any tips to get the seals in without buying a driver? Like pvc pipe? What size? Also should I do any other simple mods while I have the forks apart?

Thanx in advance for your help.


2003's still ran the 46mm forks, in 2004 they moved to 48mm - ONLY buy OEM seals, they seem to work the best.

A piece of 2" ABS tube cut lengthwise works perfectly fine as a seal driver.

When you have it apart, check your bushings - any wear on the teflon and you should be replacing them too.

% wt oil works well, a flush with cheap motor oil is fine, hang the inner tube upside down over a bucket to drain after separating from the outer..

is the '01 426 YZ also 46mm?

Yes. All YZ/YZF's from '03 back to the mid '90's somewhere had 46mm forks. All the newer ones were 48's.

Im changing my fork seals and the new ones are different. They have a little spring on them like the dust seal and the other side has a groove it it. My question is which side goes on the fork tube first? Spring retainer towards bottom of shock or top?


If there is only a spring on the one side of the seal, the spring loaded lip goes up, toward the oil.

There is actually 2 springs. I did not see one earlier cause it is inside the seal. The spring you can easily see goes towards the ground and the inside spring goes toward the oil. Thanx for you speedy reply just wanted to clear this up on this thread for future searchers.

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