Topic: Are valves universal ?

[gbutler]

Hey while rebuilding bike I noticed my exhaust valves seem a little rough. When I went to find replacements I noticed they were way more expensive than I anticipated. I’m wondering how particular valves are to their particular bikes. Or if you could replace them with another valve with the same diameter and stem length?

My valves look like they got very hot and the metal on the face looks pretty burnt. However the edge looks good and appears to sit flat after lapping. Is it a bad idea to reuse these ?
Thanks for the help.

[PeWe]

Which bike?
If exhaust valves are bad, guides are probably bad too.
Replacing guides need a seat cut.

[gbutler]

Ill load up some pictures later today. But to my eye the guides don't look bad. most of the damage seems to be on the face of the valve. the stem and the seat of the valve appear fine. Its almost as if the top face of the valve started to melt.

Really I'm curious to know if I can swap other valves in that have the same dimensions (and which dimensions would be important to match up). Or if I have to purchase original valves for a bike?

The motorcycle in question is a CB400F.

[PeWe]

I do not know CB400F.
DSS has if this is correct model.
https://www.davidsilverspares.co.uk/CB400F-SUPER-SPORT-FOUR/part_127121/

Stock is usually the lower priced valves.
Kibblewhite make good valves often used but cost more than this.

Have you removed spring, valve opened ca 10mm, wiggle the valve sideways?

You should not feel any lash, just a softness.
If you can see and feel valve has lash sideways, guide is worn, replace.