1980 GSX1100's - Sreet fun and racing

Discussion in 'UK Motorcycles' started by aus_james, Jul 7, 2005.

  1. aus_james

    aus_james Guest

    Hi all,

    Thinking of getting a GSX1100 for a bit of street fun, as a second bike
    and to then also do some classic racing (forgotten era racing) here in

    Needs to be until 1980, Dec 31st. What should I look for in a GSX1100
    1980 model?

    Any good sites for these? I'm after information.

    Many thanks,


    aus_james at h0tma1l.c0m
    aus_james, Jul 7, 2005
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  2. aus_james

    platypus Guest

    platypus, Jul 7, 2005
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  3. The GS-series had some annoying problems that could be solved if you
    knew what was happening. These are all problems that I have seen or
    heard about:

    The Suzuki GS-series had problems with the alternator stator getting
    fried, there you can buy aftermarket stators from Electrex USA, who
    also make improved twin SCR voltage regulators...

    The real culprit here seems to have been the male and female bullet
    connectors on the ends of the stator wiring and the little adapater
    pigtail on the wire harness. Its only purpose was to adapt the stator
    connector to the voltage regulator that used a different style of
    connection. The extra connections would corrode and loosen up and they
    would get hot. A permanent magnet alternator doesn't know that it's not
    charging the battery, it still puts current into the wires even though
    all that's happening is that it's burning the wiring up...

    While the wiring is frying, the stator can act like it's not connected
    to anything at all, and create too much voltage. This excess voltage
    punctures the enamel inulation on the windings and adjacent coils short
    to each other...

    You'd know this alternator problem was occuring when the battery was
    always dead...

    The early GS1100's had a habit of twisting crankshafts if you over
    revved them and backed off. This problem was solved by welding the
    outer counterweights on the 1983 models...

    You'd notice that the engine vibrated a lot if the crankshaft was

    The alternator rotor would loosen up on the end of the crankshaft and
    creep as the rider abused the RPM's. The crankshaft stub that the
    alternator bolts onto gets eaten up and the rotor taper enlarges so the
    crankshaft stub spins inside the rotor. This problem can probably be
    solved by replacing the left side end of the crankshaft with a 1984
    GS-1150 counterweight and a 1984 GS-1150 rotor. I suppose you'd need
    GS-1150 stator too...

    You'd notice that the starter spun but the engine didn't crank when the
    rotor was loose on the crankshaft...

    The GS-1100's also had a starter clutch problem associated with the
    over-revving of the engine. The three special hardened steel bolts
    holding the starter clutch to the back of the alternator rotor would
    loosen up and snap...

    You'd hear the starter clutch slapping on the back of the alternator
    rotor, and pulling the clutch lever didn't stop the noise, so you knew
    it wasn't the clutch basket...

    If only one starter clutch bolt snaps, it can jam up the starter clutch
    idle gear and throw the rider off the motorbike as it suddenly stops
    the engine from turning...

    Fortunately, I was in first gear going 10 miles an hour when THAT
    happened. The centrifugal starter clutch used on Japanese motorcycles
    seems to have been designed by Dr. Frankenstein. Gawd only knows how
    many riders have been killed when one of those things seized up at high
    Forensic engineers don't tear motorcycle engines apart to see if the
    start clutch jammed up, they just look at the skid marks and figure
    that the rider jammed on the rear brake and locked it up...

    Anyway, the starter clutch bolt breaking problem can be solved by
    welding the bolts to the alternator rotor. Of course they can never
    been removed again, but that part of the starter clutch would never
    need to be removed anyway.

    The automatic cam chain tensioner would sometimes fall apart.
    Vance&Hines used to supply a manual cam chain tensioner with a long
    bolt and lock nut replacing the automatic parts. It's easy enough to
    tap threads in the tensioner body and install your own hardware store
    variety bolt...

    A former professional drag racer told me that the clutch backing plates
    would crack where the shock absorbing springs were. The backing plate
    was just thick sheet metal and the square holes where the springs went
    were punched through. The holes would crack at the edges...

    Some large rivets in the clutch backing plate would loosen up and drag
    racers would weld the rivets. Vance&Hines made billet clutch baskets
    beefed up clutch baskets to solve those problems...

    V&H also supplied a special clutch hub nut made of hardened steel to
    replace the soft steel Suzuki nut...

    When listening to the clutch hub rattling, I would always wonder if the
    backing plate was cracking, but it didn't crack on me...

    If you can replace the stock Mikuni CV carbs with something else, the
    racers of the era were using Mikuni VM33 round slide smoothbore carbs.
    They have a return spring like a garage door spring, it's a lot of work
    to turn the throttle, and they stick under vacuum when you roll off the

    36mm or 38mm Mikuni radial flat slide carburetors with accelerator
    pumps would be a better replacement carb...

    There's more power to be had out of the engine by installing cams with
    more duration, but if you're running on tight short race courses, a
    better way to go is to advance the cam timing about three degrees on
    both intake and exhaust cams so the intake and exhaust valves close
    earlier. This gives you more mid-range "grunt" so you don't have to
    shift gears as much. You just sit forward with your balls on the gas
    tank and ride the
    machine like it was a giant motocross bike, running deep into the
    corner, squaring it off, and gassing out of the corner...

    The lobe centers we used to degree the cam were 107.5 degrees.You can
    slot the cam sprocket bolt holes with a rat-tailed file to move the
    sprockets in relation to the cams...
    Kalifornia Kritter, Jul 7, 2005
  4. aus_james

    Martin Guest

    [snip list of woe]

    Sounds like a bit of a shit bike all in all.

    "For a minute there, you bored me to death."
    VTR1000 Firestorm
    TDR250 http://ukrm.net/BIKES/Yamaha/tdr250.html
    martin dot smith nine zero three at ntlworld dot com
    Martin, Jul 8, 2005
  5. aus_james

    k_fl.... Guest

    A guy who built a GS-1000 for drag racing told me that he had to spen a
    lot of money on aftermarket parts to keep the engine from
    self-destructing under the additional power. He said that if he'd known
    that at the beginning, he would have bought a KZ-1000 instead...

    But, in that era of 1980, if you wanted a 16-valve engine of 1100cc
    displacement, what were your choices? The GS-1100 with its high tech
    twin-swirl combustion chambers that used fuel more efficiently or the
    rarer, hotter-running less fuel efficient Honda CB-1100F...
    k_fl...., Jul 8, 2005

  6. I don't know what the ratio is today, but in 2000, 16 of the top 20
    NHRA drag bikes used the 1977-1985 series Suzuki GS engine, even after
    it had been out of production for a number of years. There are
    big-bore kits available up to 1500cc and larger, and a wide variety of
    go-fast parts to support the engine.

    Here's are some race results from late last year:


    Of the sixteen starters, all but three were Suzuki-powered. Some
    engines were listed as "Suzuki GSXR", while others were just listed as
    "Suzuki", but I don't know for certain what the difference is.

    I've never raced one, but my wife's previous bike was a GS1100L, and
    other than replacing the stator (a common problem with the GS series),
    it never gave us a bit of trouble.
    Scott Gardner, Jul 9, 2005
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