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I changed the rear sprocket on the YZ and after reinstall I couldn;t get the rear brake to pump back up. I tried bleeding every which way I could with no sucess,
went to sears spent the $38 on a vacuum bleeder and had it fixed in 3 mins. it actually took me longer to get it out of the package than to get the rear brake working again.
its one of those things that you don't think much of until you use one .
spend the money and save the hassle .