Bleeding epic

Today I finally got round to fitting the front master cylinder piston
kit and new caliper seals on the SO YZ250.

The caliper job was easier than I expected, though I had to use my
compressor to get the pistons out and scratched my head a while as to
how to apply the air to the caliper. In the end I took off the quick
connector from my rattle gun and found that applying the end of that to
the banjo connection and pushing down hard on the connector gave a good
enough seal and a controlled blast as required.

I knew that when it came to refilling the system with brake fluid it was
likely to be tricky from when I borrowed the lad's spare YZ85 master
cylinder. With a completely empty system it was even worse. SO Morini
Grimecas are so easy in comparison. I suppose I should get a Mityvac,
but it's a job I don't intend to do regularly. In the end I had to leave
the caliper off its mountings and hanging down as low as it would go
whilst I laboriously tried to work fluid through. The air turned blue
with some examples from Nige's repertoire. It took ages until a few
drips emerged from the bleed nipple, and at last a decent dribble I
suppose it's because the hole in the reservoir through which all fluid
has to reach the parts is tiny and the hose, being on a crosser is v.
long. Put the caliper on properly and after feeding it with even more
fluid got a decent spurt on pulling the lever. Hooked up my one-man
bleeding kit tube and finally started to get some pressure and
encouraging bubbles. Eureka a working brake, and even better one that
doesn't drag. So it looks like it was the caliper seals after all. Just
as well, as a new caliper was going to be £350 and the refurbishment has
only cost about £25, including a new actuating rod and nut for the
master cylinder as the thread was chewed up on the old one.

Oh, and I got the (Motoplat) flywheel magneto stator off the GFR
(fortunately already featuring alignment marks). The rotor was on bloody
tight, but the puller eventually shifted it from its 16 years marriage
to the taper with a bit of soft hammer assistance. West Country Windings
say they can definitely rewind the ignition bit, which looks
suspiciously like the Bosch 'charging coil' on my old Rotax 250 MX
motor, though hopefully with not such tiny gauge fragile windings as on
that.

A good days fettling - beer has been consumed.


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| Pete Fisher at Home: |
| Voxan Roadster Yamaha WR250Z/Supermoto "Old Gimmer's Hillclimber" |
| Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" |
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Really all you need is a 50p syringe from the chemist. Use it to fill up
the lines in reverse, having loosened the banjo at the master cylinder.
Making sure the m/c is full of course. Do the same to the caliper through
the brake line hole then close the bleed screw. Attach caliper to brake
line. Bleeding the system will now proceed with zero aggravation and there
wont be much air left to remove anyway.