Original factory springs vary considerably, but all use 0.6mm wire, coil diameter of 5.3mm, 41-1/2 to 43-1/2 coils with closed and ground ends. A new spring will measure about 123mm at rest; after a little use it will take a set to about 115-117mm. If it’s kinked or appreciably shorter than that, replace it. Otherwise, leave it alone.
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