base valve all busted up

as i was changing the iner-cylinder oil on my 2008 yz250f i noticed the plastic piston that has the two o rings were covered in hairline cracks? ***! anyone heard of this problem and what should i do? thanks a bunch. want to go brap!

You probably need to replace it. Those pistons are actually made of a thermosetting polypropelene because of their resistance to chemicals such that are found in suspension fluid. Although this is a good material for the job, they can be quite brittle and do sometimes crack. Can you post a picture?

i put it back in so no pic now. they had micro horizontal cracks running all through them. should i go to yamaha or is that part replaced at the tuning shops when they do the custom set up. thank you!

do i have to get this part from yamaha or do they make an after market part?

You can get them from KYB dealers, eg Smart Performance, MX-Tech, Enzo Racing, etc

I'm not sure if you could get them from Yamaha. but even if so you don't want to buy them there because most likely they would cost a fortune.

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