How Much Fork Oil 03 YZ???

So my buddy bought an 03 YZ with suspension work fitted for a 6' 3" 225 lb dude, my buddy is 5' 10" and maybe 185lbs. can he (for now) just go with a less weight fork oil to compensate? if so, how much oil will he need?

Thanks In Advance, Dube2

The fork oil can partly compensate for too heavy springs, but only partly, and not by reducing the viscosity.

The air trapped in the fork above the oil becomes a de facto spring in its own right. Raising the oil level stiffens it, lowering the oil softens it.

Changing viscosity has not much effect on modern suspensions beyond the initial clicker settings because they are designed to work consistently across a wide temperature range, and the shift in viscosity in a 7wt fork oil from cold to operating temp is greater than the difference between a 3wt and a 10wt.

Oil in the '03 is set by adjusting the level, not the amount. With the springs removed, and the main tubes and damper rods both compressed (and the air worked out of the damper), the level is set at between 85 to 135mm below the open top of the tube. It takes a bit more than a quart to change the oil on this model.

Thanks GR, that will help a lot.


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