Do valve guides need to be reamed if they aren't removed?

Hey all,

I think this is a really basic question but I'm struggling to find an answer.

If I remove the valves from a KZ400 (or any KZ I guess) head for a gentle clean and measure but leave the guides in place, do I still need to ream the guides before reinstalling the valves?

My confusion comes because the shop manual treats the valves and valve guide removal/reassembly as one job and states 'Ream the valve guide with the valve guide reamer even if the old guide is reused'.

Also, since the manual writes it like that, is it necessary to remove the valve guides if I'm already removing the valves? I thought I could leave them in place and measure wear with the wobble method before committing to removing them only if they need replaced.

Bonus points if someone can explain why the guides need to be reamed even if re-used.

Appreciate any advice!

No need to touch the guides if re-using the original valves and the guides haven't been removed and refitted.
 

It is, however, absolutely essential to mark the valves and return them to their original position.

H.

Thank you both, really appreciate the help!

wrote:

It is, however, absolutely essential to mark the valves and return them to their original position.

Thanks, will do. I'll write a little addendum in my manual to cater to the reaming without valve removal and remind myself to keep all valve components together and return them to where they were.