Motorcycle Repair: 1984 venture clutch issue, motorcycle salvage yards, tiny air bubbles

Question
Glad to see there is people like you helping us out.
I recently bought a 1984 xvz1200 yamaha venture. Everything was perfect until i came to a stop and pulled in the clutch and she stayed engaged. I limped the bike off the street and put it into neutrel and pulled the clutch in again and dropped into 1st gear and bang she tried to take off on me. NO matter how hard i squeeze the clutch she stays engaged. If i can take off like that shifting up or down is just fine. Today i bled the system and founds alot of air. I thought it was all out but it didnt help the problem.the clutch handle seems weaker but just a little. I have to wonder where all the air is comming from ? doesnt appear to be leaking anywhere. Its been suggested to me that i replace the slave and or install a new clutch pack. What is your opinion and where can i find parts like that for this old of bike.
regards
Wayne

Answer
Hello Wayne,

Parts are getting tough to find for these
older bikes unfortunately.
Sometimes you can get parts from Yamaha and
the rest from sites like Bikebandit.com
That leaves motorcycle salvage yards as the
last resort or often Ebay will be helpful.

The hydraulic clutch systems often form
tiny air bubbles that are hard to get out.
The system can be bled thoroughly and
then tapping the lever lightly will
sometimes dislodge the small bubbles.
You must always keep the master cylinder
reservoir on the handlebars full
of brake fluid or air can sneak in.

If the handle feels fairly normal
as in having some resistance when
you pull on it then it may be some
other problem than air.

Just bleed it well by pulling the lever
in and loosening the bleed screw
on the brake wheel caliper.

When the lever hits the handlebar,
tighten the bleed screw a bit
and repeat. Only release the lever
when the bleed screw is closed
to prevent air intake.
You can attach a 3/16" hose
to the bleeder screw and run it into
a jar with a bit a brake fluid in
the bottom. This will keep air from
getting back in.
Keep the handlebar reservoir full
of brake fluid when bleeding to prevent air
entry.
This can be messy and bad for paint
so be careful.

Once the lever feels okay and if the clutch doesn't work
it may need further checking.
The clutch has some little push rods that
go through it's center.
The clutch slave cylinder pushes on these to release the
clutch. If they get worn or bent the clutch plates
may not release.

The outer clutch basket may have wear grooves
in it that keep the clutch plates or discs
from separating properly.
The plates may not release if they are
burnt or bent either.

If you pull the clutch cover off you
may be able to see if the
slave cylinder push rod(s) are pushing the plates apart slightly
when you pull the clutch lever or if the clutch smells burnt.

The clutch push rods may have to be removed and inspected
to see if they are bent.
One small one is near the clutch end
and the longer one goes through the
engine to the slave cylinder.

You may be able to get some slave and/or
master cylinder seals kits online
or maybe some Yamaha dealer if necessary.

I would probably bleed it well
and then check if the clutch plates
and push rods are okay first.
Look at the clutch basket when you pull
the lever, it should just try to
separate the plates slightly if working.

The plates should be flat and not worn/burnt.

I hope this answers some of your questions.