I've got a 03 fatboy. I just replaced the front brake pads, while doing it I removed majority of brake fluid and replaced with fresh. My question is in the service manual it says to fill within 1/8 of an inch from gasket surface. But no matter how you stand the bike or turn the bars the reservoir is never level, so where in the reservoir do you measure the 1/8" and with the bars straight or turned to the left, bike on jiffy stand or standing straight up. Also I never noticed when I removed reservoir cover that it is wedge shaped, I'm guessing that the thicker part of wedge goes to the outside of the bars to accommodate fluid level? Would appreciate any and all help in this matter. Thanks

 

Measure at the mid-point of the reservoir, between highest and lowest points. To be honest I would only do that by eye, not with any measuring tool!

I don't recall any wedge-shaped caliper lids, is yours stock? Post a photo, so we can take a look.

 

Get it as level as you can and then keep the fluid 1/8"-1/4" down from the point (edge or corner) of where it would run out of the reservoir. You don't want the insertion of the gasket/bellows to push out (displace) the fluid.

The Thicker part goes towards the Inside of the bars.

Not all manuals mention this, but the ones that do, say something to this this effect:

"Note: that one side of the master cylinder reservoir cover is
thicker than the other. Install the cover with the thicker side
closest to the brake line fitting."

OR