Jump to content

Valves

Recommended Posts

So last night I did a oil/filter change and decided I need to check the valves on my New to me YZ 450f.    Intake perfect bang on.  Slide a .10 it goes in, slide a .15mm nope so thats great.  Go onto the exhaust side.  Slide a .20 in no issues, move up to a .25 in it goes.  OH SHIT.  Up to a .35

how does it get a larger gap?  I thought they were suppose to decrease and tighten up?

So my question is do I tackle this on my own or take it to the shop?

Share this post


Link to post
Share on other sites

Carbon building up on the valve seat. Since it is the exhaust all the burnt gases are leaving the cylinder through those valves. As the gases are rushing out they leave carbon behind. It builds up on the valve seats and increases the clearance. The proper way to fix it to pull the head off and remove all the carbon build up. Not a hard job if you have a valve spring compressor and some basic tools. Basically just pull the head off, take the valves out, clean the valve up with a wire wheel then clean as much carbon off of the head it's self as you can. Put the valves back in and put the head back on. If you do wanna try this yourself you gonna need a c clamp style valve spring compressor.

Share this post


Link to post
Share on other sites

doesn't sound like a fun job.   I don't have any valve tools.   I am going to google and see what is involved.   Also sounds like an expensive job.

Share this post


Link to post
Share on other sites

I am going to have another look tonight.   Problem is those valve tools are not super cheap close to $200 here in my area for a decent one.

seems to be an issue on exhaust side from what I have been reading.   

they should make something you can add to fuel to reduce this from happening.

 

Share this post


Link to post
Share on other sites

The PO may have adjusted the valves before and did it wrong.

I'd adjust the valves properly and call it done.

If carbon was holding the valve open the bike would be hard to start.

  • Like 2

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:


×