Jump to content
Sign in to follow this  

base valve all busted up

Recommended Posts

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!

Share this post


Link to post
Share on other sites

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?

Share this post


Link to post
Share on other sites

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!

Share this post


Link to post
Share on other sites
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!

they probably will brake soon. its frequently asked here, just picked the last 2 posts:

http://www.thumpertalk.com/forum/showthread.php?t=984288

http://www.thumpertalk.com/forum/showthread.php?t=952026

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×