Newsgroups: rec.motorcycles
Subject: rec.motorcycles FAQ of 93.01.01    (Part 3 of 5)
From: dave.williams@chaos.lrk.ar.us (Dave Williams) 
Date: 10 Jan 93 04:42:00 GMT
Reply-To: dave.williams@chaos.lrk.ar.us (Dave Williams) 
Distribution: world
Organization: The Courts of Chaos * 501-985-0059 * Public Access Usenet


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Q:  I've been looking to buy a [brand and model name not important].
    Several people have told me those bikes have troubles with second
    gear.  How can I tell if this one is OK, and why do they have this
    problem?

A:  Second gear problems are the most common of all.  They tend to be
    worse on high-power machines.  Typically, the rider doesn't get
    the gear all the way into engagement, and it pops out under hard
    acceleration.  This typically rips metal off the engagement
    surfaces, making it that much easier to pop out the next time.
    Eventually the machine will pop out of gear under acceleration.

    Incorrectly adjusted clutches, careless shifting, and shifting
    without the clutch can all cause second gear problems. The fact
    that you could shift your dirt bike without the clutch is not
    relevant; your dirt bike probably doesn't weigh 550 pounds, run
    on pavement, and have a fat tire on the back.

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Q:  My motorcycle seems to use up chains pretty fast.  How can I tell
    the difference between a good chain and junk chain?

A:  I wrote an article for Australian Motorcycle News which covered
    this subject in detail.  I've reproduced it here:

    Years ago chains were considered disposable items. I remember
    scraping up money for the spring chain and sprocket ritual every
    year when I was in high school. Sometimes the chain wouldn't make
    it through the summer, even with fanatic oiling. Every T-shirt I
    owned had an oil stripe down the back on the left, much to my
    mother's dissatisfaction. I once had a two-month-old chain on my
    175 Kawasaki snap while going 50mph. The broken chain wrapped
    itself around the swingarm and locked the rear wheel solid,
    whereupon the rear wheel decided it would lead for a while. By some
    miracle I came to a halt still vertical, but I have had a paranoid
    distrust of chain drive ever since.

    Now what, might you ask, would cause a chain to break like that? It
    was properly lubricated, adjusted, and running on the correct size
    (new) sprockets. Chances are that the local motorcycle shop had
    sold me some ordinary industrial chain instead of motorcycle chain.
    Such unscrupulous dealings were far more common years ago than they
    are now. A real chain might cost $30 then, but farm machinery chain
    sold for a little over a dollar a foot. What's the difference?

    In its simplest form, the roller chain consists of side plates,
    pins, and rollers. When properly lubricated, this type of chain
    will perform acceptably for most engineering purposes.
    Unfortunately, proper lubrication consists of an oil fog or bath
    and freedom from dirt, both conditions unlikely on a motorcycle.
    Twenty years ago some machines still came with enclosed chains, but
    the enclosed chain died away not because of styling, but because it
    was a tearing pain in the arse to service the chain or rear wheel
    with the bulky (and oftimes leaky) enclosure in the way.

    The oilite-bushed chain assisted the enclosed chain to oblivion. A
    porous bushing was pressed into the roller and rode on the pin.
    This porous bushing was impregnated with lubricant and would absorb
    chain lube too. With a moderate amount of maintenance the bushed
    chain was satisfactory if not perfect. Since the mid-1960s all
    "real" motorcycle chain has been of the bushed type. The chain that
    caused my hair-raising ride was likely of the previous type.

    In the mid-1970s the "O-ring" chains came into use. These were
    bushed chains using O-ring seals to keep the lubricant in and dirt
    and water out. They represent the latest word in drive chain
    design, being reliable, long lasting, and low-maintenance. Indeed,
    when run on plastic sprockets, the O-ring chain may need no other
    lubrication during its operational lifetime.

    Modern motorcycle chains come in two basic types - those which are
    endless, and those which use master links. Endless chains came
    about when engineers realized that most catastrophic chain failures
    ocurred at the master link. By eliminating the master link,
    reliability could be enhanced. Unfortunately, endless chains can
    cause a problem if the sprocket sizes have been changed much; if it
    is too long or too short, nothing can be done. Endless chains also
    usually require time-consuming removal of the swingarm for
    replacement.

    Motorcycle drive chain contains two kinds of links. Roller links
    consist of two side plates, two rollers, and two bushings, all a
    slip fit over the drive pins. Pin links consist of two side plates
    and two drive pins, with the pins being a tight press fit into the
    side plates and staked in place for permanence. These links
    overlap, rollers on pins, to make the complete chain.

    Most chain is made in inch-based sizes, because the standard chain
    dimensions were established before much of the industrialized world
    had adopted the metric system. The basic chain size is given in
    terms of pitch, which is the on-centers distance between the
    rollers. The roller diameter is standardized at 5/8 of the chain's
    pitch dimension, so the common 5/8-pitch chain has a roller
    diameter of .391 inches. Unfortunately, no such uniformity exists
    in chain width, which varies a lot, as does sprocket thickness.
    Running a chain on sprockets which are too wide is usually a feat
    beyond even the most mechanically disinclined; unfortunately, it is
    also possible to run a chain on sprockets which are too narrow. The
    results of this are not good - the chain usually runs to one side
    of t