I just got a pair of used Elka stage 4 shocks for my kfx450r and measured them to be 18" eye to eye. Does anyone know if this is their actual shock length? Or if they are just adjusted to be that way right now?
18" is the max they will extend, period.
Check to see if the springs turn freely by hand... this is zero preload... If not they have some unknown amount of preload on them.
Once on the quad and supporting the weight of the quad they will compress some (normal).
Recruit a friend who can read a ruler and take it somewhere flat like a garage floor. I like to park the front tires on a couple of pieces of cardboard like a pizza box, then have someone push down on the front bumper while I turn the bars back and forth.
This allows the front to settle as it would in the dirt.
The front tires scrub out as the front end is compressed.
Afterwards, have the friend measure from the floor up to the frame just in front of the peg. Then take another measurement at the last forward point of the frame before it turns up into that single spar... right in front of the radiator...
You should be level or pretty close.
If the front end is low with you aboard you can add a little preload... about 3 threads... or go to zero preload in the rear.
If the rear is low you can stay with zero preload in the front and go as far as about 3 threads of preload in the rear.
A "general rule of thumb" is that if you can't achieve ride height with the above, something needs to change on your springing. You'd have to post up some ride height measurements for suggestions