Problems topping-off brake fluid

[Fixxxer]

I've been reading a lot about doing a brake fluid change over the last few days since that's the last item left on my fluid change "to-do" list. I'm probably going to wait until next month to do it, so in the mean time I was going to just top off the front reservoir, since it looked a little low. It's might be worth noting that my brake pads look to be in good shape. I don't know how thick they are new, but mine still have a lot of meat on them.

With the bike on the centerstand, and the handlebars straight ahead, the fluid is just barely visible at the bottom of the sight glass (i.e. it's well below the "min" mark). So, I turned the handlebars to the left (I even set a level on top of the reservoir to make sure that it was perfectly level) and opened up the reservoir. To my surprise, I found that it was almost completely full. I was scared to add any more for fear of it overflowing. I'd say that there was only about 2mm of space between the brake fluid and the front lip of the reservoir.

So, what's the deal? If my sight glass says the fluid is low with the handlebars straight, how am I supposed to add any fluid if the reservoir is full when I level it up (bars turned left)? Is there a trick that I just haven't been able to find yet?

Also, I noticed that some of the screws holding the reservoir cap on had the heads partially stripped... Does anyone know where I can get some replacements?

Thanks!

[signit98]

...you are supposed to check with the handle bar turned to the oposite direction so the reservoir is almost level when the handlebar is turned to the other side (for your front brake that would be all the way to the left).
This setup is very decieving... but you must not worry if it looks like it's empty when having the handlebar straight... as you have come to find out!
You should be able to find these (metric) screws at every good hardware store...

[5axis]

Perhaps someone will chime in with bike specific info for you.

Generally you should run the fluid levels at about mid point. Under hard braking the fluid heats up and expands. It needs to expand into the reservoir otherwise it will expand into the brake calipers and put the brakes on. Then the friction gets worse, and the heat higher, and it brakes harder, and so on.

Track bikes are often run on the low side because of this issue.

[Fixxxer]

That's what I thought too (check it with the handlebars turned to the left), but the repair manual says to check it with the handlebars centered. It's weird though, since it also says to check the clutch fluid with the handlebars turned to the right (not centered)...