i just installed new progressive fork springs on my XS this morning and let me say WOW it made a huge difference on fork bottoming and braking dive. With drewpy"s help on the OE specs i found progressive makes fork springs that will work in the XS400 even though they do not list an application.
the OE fork springs are .4/.575 kg/mm
progressive makes .54/.71 kg/mm (ps11-1115) and .63/.80 kg/mm (ps11-1109)
i installed the .54/.71 because i found a set at work with 10 years of dust on them. just took the bike for a ride and could not make them bottom for the life of me. its huge.
the OE fork springs are .4/.575 kg/mm
progressive makes .54/.71 kg/mm (ps11-1115) and .63/.80 kg/mm (ps11-1109)
i installed the .54/.71 because i found a set at work with 10 years of dust on them. just took the bike for a ride and could not make them bottom for the life of me. its huge.