Topic: CB650 valve springs info and upgrade

[Crater]

Hi,
I am tearing down a neglected 1979 CB650 for rebuild to swap into my 550 frame. I have searched for replacement valve springs and a potential upgrade. I can’t find any info on my stock valve springs other than their heights. Does anyone know what the valve seat pressure should be? I am not sure if they need replaced or not.

[fizzlebottom]

My FSM also only shows service limits for free lengths of the springs. Inner springs, both intake and exhaust need to be 37.9mm (1.49in.), and outer springs need to be at least 43.3mm (1.70in.)

I'm not a spring engineer, but I'd assume that this is the only measurement the Honda engineers intended to use. I hope you find what you're looking for.