Port and Polish

Does anyone know if porting and polishing a '99 YZ400 head is actually a do it yourself job? I've seen on car shows how easy it seems but obviously this is different. Has anyone done it? Is there anything to watch out for?

I polished and cleaned up a 426 head a couple of weeks ago. I found that the area below the valve seats were slightly mismatched and required some grinding to blend the port to the seat. The ports themselves were not to bad as far as shape and imperfections go. If you attempt to do this work yourself I would focus on the area below the valve seats and being careful to mantain the basic original shape of the port as it leads into the valve seat. Also be careful not to nick or damage the valve seat area while grinding. If you have had some experience with a dremel tool or die grinder you could probablly do this with time and patience, otherwise send it to a pro.

Create an account or sign in to comment

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

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now