Clutch/Starting Problems?

I have a 1982 Honda CB 125s. I have been restoring it. Have not had
the bike started yet.
I have spark, compression, carbs working.

Clutch doesn't seem to be doing anything. In first gear, there is
hardly any difference between the clutch engaged and disenaged.
Transmission works fine, but clutch doesn't seem to be clutching.
When I try to push start the bike, the piston doesn't move with clutch
enganged or disengaged.
The piston does move if I try to kick-start it, but I can't start the
bike that way. A friend told me I would probably have to push start
it to get it started the first time.

Any suggestions on the clutch problem?

Or any suggestions on getting the engine running?

Thanks
Hammer

 

That sounds like a typical motorcycle clutch, especially one in an old
motorcycle that hasn't been running in a while. The fiber and steel
clutch plates stick together, the fiber plates don't slide freely in
the slots in the clutch basket and the steel plates don't slide freely
on the center hub.

If you want to look at diagrams of your Honda's clutch and kick
starter, go to www.partsfish.com or to www.bikebandit.com to see them.

Your Honda's clutch was designed by Japanese student engineers who
just learned engineering and English from a Dr. Seuss story that
described an animal called the "Hillside Snee".

Its downhill legs were longer than its uphill legs and it had to walk
around the hill in one direction to get where it wanted to go. If it
had to immediately reverse directions, the only solution was to jump
backwards through its mouth and come out its ass.

And that describes the bass-ackwards Honda clutch, which is built with
the pressure plate all the way inside the clutch basket.

The kick starter system is an obsolete design that does NOT allow the
rider to kick start the engine when the transmission is in gear
(unless the rider doesn't mind the whole motorcycle moving forward as
he kicks on the lever).

If you look at the TRANSMISSION KICK STARTER SPINDLE diagram, you will
see item # 21, called "spindle".

When you kick the kickstarter lever, you turn the spindle.

Item # 20 is called "ratchet". It has a protruding ear that keeps the
spindle from turning so far you hit your foot against the foot peg (or
the ground)

The ratchet engages the gear on the spindle and turns the gear (item #
19).

That gear turns a gear on item # 3, called countershaft.

The gear on the countershaft is *always* engaged with a gear on item #
2 (the mainshaft).

The mainshaft is *bolted* to the clutch center hub. If the mainshaft
turns, the clutch center hub has to turn with it.

The steel clutch plates have to turn with the center hub but they can
slide a little bit sideways. That's normal.

The clutch fiber plates are held in contact with the clutch steel
plates by four springs. The clutch fiber plates then transmit the
motion of the kick starter to the clutch basket.

The clutch basket is geared to the crankshaft by its own larger gear.
If the clutch basket turns, the crankshaft has to turn.

When you kick on the kick starter the piston has to move as long as
the piston rod is still connected to the crankshaft.

I suspect that there is nothing at all wrong with your clutch.

I don't think that the clutch is really the problem. You probably
aren't getting the transmission into first gear because of sticky
sliding gears.

What happens when you try to make the crankshaft turn by putting the
transmission into second, third, or fourth gears?

Try rolling the motorcycle backwards a bit and then forward while
working the clutch lever and the shifter lever to make the
transmission sliding gears slide sideways to engage the pinion gears.

If you can't get the transmission to engage all the gears, you may
have to drain the engine oil and refill the crankcase with kerosene to
dissolve any goop that is making the gears stick.

If that doesn't work, you may have to disassemble the engine to get at
whatever parts are keeping the transmission from engaging all the
gears.

Turn the idle speed screw all the way out so the throttle closes
completely. That will make the engine suck fuel out of the float bowl
easier. You can readjust the idle speed after the engine warms up.

 

Start by checking the tension on your clutch cable (I'm assuming that
it's a cable-operated clutch, as I've no familiarity with this
particular bike). Too tight a cable can prevent the clutch from
engaging, allowing the rear wheel to spin without spinning the engine.
The next thing to check is the operation of the clutch that cases, and
to pull the clutch and check the steels for thickness and signs of
overheating or warping.

It's not entirely clear to me why the clutch might prevent the
kickstarter from working, though. Why would you have to push-start the
bike the first time?

--
Later,
John



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