Fluid replacement - second hand YZ450F

5 replies to this topic
  • chrispa

Posted June 07, 2011 - 06:41 PM


Hi guys,

I just purchased a second hand 2008 YZ450F, according to the hour meter it has done 40 hours so far (who knows when that was fitted).

I do not know for sure the prior maintenance history on the bike, it looks in very good condition (face value) and rides very well.

I was considering changing all of the bikes fluids. I plan to change oil, coolant, but is it necessary to change brake fluid as well (as this is a little more involved). Is there a way to inspect the brake fluid to see if it requires replacement? The manual suggests changing it every year, but I think this is a bit of overkill.

  • long arm

Posted June 07, 2011 - 11:14 PM


I would do it just to be safer than safe. Brake fluid degrades with time and exposure. It's cheap and although more involved than changing oil still not diffucult to replace.

Do you NEED new brake fluid? Probably not but I'd bet you the last guy didn't do it either.

Brake fluid should be clear to applejuice colored. It should be replaced when it darkens too much or becomes gray, dark brown, or black. You can just flush the brakes out, that way you're swapping the fluid and doing the bleed all at the same time.

  • yz450fcranker

Posted June 08, 2011 - 02:50 AM


do not change the brake fluid because if its working it should not be replaced just filled up
just add juice

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  • grayracer513

Posted June 08, 2011 - 06:24 AM


Brake fluid gets dirty and absorbs water from the air with any exposure it may have had. When it gets wet, it boils too early, and steam won't stop the bike.

It's actually a very simple matter to replace it. Start by pushing the pads back a little and then pumping them back down. Do this two or three times to agitate the fluid and put any solids in suspension in the fluid. Open the reservoir and be sure it's filled. Loosen the bleeder screw so it's more easily opened, apply pressure to the brake and open the bleeder, making sure to close it before you let up on the lever. Check the reservoir level and repeat that once more.

Now, with no pressure on the brake, open the bleeder and just let the fluid drain from it, keeping the reservoir full as the level drops. Once the fluid draining at the bleeder looks new, you're done.

  • dalonar

Posted June 08, 2011 - 07:20 AM


what gray said, let gravity do the work. as was mentioned before brake fluid absorbs water and will go "bad" after a while. it may still work fine for your application but why not have new fluid!

  • Steel Panther

Posted June 08, 2011 - 06:34 PM


Here is a pretty good instructional video on how to bleed/change the brake fluid. Its actually pretty easy.


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