Jump to content
Sign in to follow this  

CRF 80 - valve spring shims

Recommended Posts

OK fellas, I have a few posts on here about my wifes 2004 CRF 80. I went ahead and got the cylinder bored out 1mm oversize and picked up a new piston kit. The engine was smoking and I found a bad valve when I tore it down. I de-carbonized the head and have two new valves to lap in and put the engine back together.

I found two thin flat washer looking pieces on the ground. Initially I thought it was one, but there are two stuck together and aligned perfectly. They fit down in the cut outs in the head where the valve spring sits.

1.) The odds of them falling out (one from each valve location) and landing/sticking to each together perfectly is slim and none.

2.) I am assuming they are shims to get the spring pressures where they need to be.

3.) I checked the online engine schematics and do not see them anywhere. How do I fingure out where they go? Are they intake or exhaust?

Any thoughts?

Share this post


Link to post
Share on other sites

they go under each of the valves to prevent the spring from hurting the aluminum head. why they ended up together is beyond me, but there should be one under each spring.

Share this post


Link to post
Share on other sites
they go under each of the valves to prevent the spring from hurting the aluminum head. why they ended up together is beyond me, but there should be one under each spring.

Now my intake valve was hammered from (in my opinion) too much spring pressure. The valve cut face was being pulled into the seat too hard and it really distorted the surface.

I am thinking that it was installed incorrectly either from the factory or from a previous owner. It would be a one in a billion shot of them landing perfectly together.

Thanks for the input, it makes perfect sense.

Share this post


Link to post
Share on other sites

i dont want to tell you whats wrong with your head, or what caused the intake valve to do what it did, just make sure there is a spring seat (your thin flat washers) under each valve spring before assembly. also if you removed the valve stem seals, make sure the spring seat can pass over them before you put the new seals on...otherwise you will have to install the seats before the new valve stem seals and on.

Share this post


Link to post
Share on other sites
i dont want to tell you whats wrong with your head, or what caused the intake valve to do what it did, just make sure there is a spring seat (your thin flat washers) under each valve spring before assembly. also if you removed the valve stem seals, make sure the spring seat can pass over them before you put the new seals on...otherwise you will have to install the seats before the new valve stem seals and on.

Thanks for the help, I appreciate it! :thumbsup:

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  

×