Magura master cylinder warning.

I belive everyone notice this but still I think I need to warn.
Found unused magura master cylinder from my part bin and decided try it
to Trident. Yes, it worked very well, only problem was get light switch
to fit. Magura do not have any space between handlebar and reservoir. So
I make clamp over two switch bolts and it seemed to work, even it is
open from cylindr side. I put thin plasic sheet to make somekkind
protection.
Brake start to work very hard (2 caliper alloy locheed), I was busy at
home from garage so I didn't made any final cheks before leave.
I should. ride about 2 miles, brake started to feel more and more hard
and level touch more and more up until, after about 3 mikles, just
before motorway, it stopped totally. First I thought engine was stucked
but press the clutch didn't make any help for movement. So, rationally I
thought it must be brake and it was, front brake was totally stucked. I
belived there must be adjustment somhow in master cyluinder as it
started to behave so strange. There wasn't but when I removed level, I
found that because I had pushed throttle handle as far as it goes, it
pressed master cylinders open piston.
So, if you use magura master cylinder with separate british throttle
handle, leave about 1/2" space between magura joint and throttle.
Now I have good brakes and magura level screwed with massive adjustable
spanner as I couldn't find better from my toolbag.
Veli

Hi Veli,

I believe you experienced the pressure release hole being blocked between the
reservoir and the master cylinder bore.

The MC has two holes from the reservoir to the bore. You can look into the
reservoir and see them but sometimes a plastic 'tab' is over them to block
squirting. The largest hole farthest away from the hose end is a supply hole
and is behind the lip of the MC piston. The smallest hole (this can be super
tiny) is closer to the exit and just in front of the piston lip. The tiny
hole's purpose is to release brake system pressure that is built up from the
heat of operation. What many folks experience but never quite know is, the
simple fault of that tiny hole being blocked will build pressure until the pads
drag, the caliper gets hotter, pressure builds, pads drag harder and so on
until the wheel locks. Poke through the hole and flush the system from the top
down and you should be good to go.

Tom Graham

Many times, old brake hoses deteriorate and the stray rubber acts as one-way valves.