Suzuki's GN series, is there any love for 'em out there?

Discussion in 'Old's Cool' started by DoubleBit, Jun 18, 2010.

  1. Andyvh1959

    Andyvh1959 Cheesehead Klompen

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    814
    Location:
    Da frozen tundra eh? 1.5 mile west of Lambeau
    I'm the "Andy" on that GN400 Yahoo Group forum with the ice bike pictured there.

    I should have my new combination CDI/Coil/Plug wire system by next week. Its an adjustable AC fired CDI system that I hope will give me a matched CDI and coil setup. Plus its adjustable for the advanced timing curve, which should give me the range to get the rpm up.

    And I should have my magneto rotor puller by this weekend. So I can pull the rotor and make sure the timing is correct, or at least prove the rotor key has not sheared.
    #21
  2. eric123

    eric123 Gott Mit Uns

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    Idaho
    Your bike was my desktop wallpaper for quite awhile...
    #22
  3. royota

    royota n00b

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    Oct 20, 2012
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    I'm new here and was wondering if there was anymore word on the Chinese cdi unit working on the gn400.... thanks for the info so far..
    #23
  4. jings

    jings Been here awhile

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    Location:
    dumfries scotland
    [​IMG]
    #24
  5. royota

    royota n00b

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    Nice bike do you have more pics of it..
    #25
  6. jings

    jings Been here awhile

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    dumfries scotland
    no only one ive got think it was off the pipeburn site
    #26
  7. dpforth

    dpforth no inline fours

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    Location:
    Fantasy, I mean Vancouver Island
    #27
  8. plugeye

    plugeye mc caregiver

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    May 11, 2007
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    Location:
    Garland, Texas
    i love them.
    trying to get my buddy to sell me his basket case
    #28
  9. ArtCuisin

    ArtCuisin Adventurer

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    Sep 20, 2011
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    35
    I had one back in the eighties. It was a commuter for me. I had
    a huge topbox on the rear rack. I treated it gently as though that
    was all it was. Every night, I would ride this 270 degree downhill onramp.
    Over time, I rode it faster and faster. One night, I hung the rear
    end out accidentally and it felt fine. After that, things were
    never the same. Even though a commuter, Suzuki did use
    tapered roller bearings in the steering head. I always wondered
    if that was the reason for the good (to me) frontend feedback.

    After about 40K of commuting, I stripped it down for the winter
    and painted every nut and bolt on the bike. I added clubman
    bars--really comfortable because the steering head is really
    high, like that of a cruiser, but it looked pretty cool. I kept
    the chrome fenders. They looked good against the flat-black.
    At the time, Powroll in Oregon still existed and they had a
    simple slide-needle carb kit to replace the constant velocity
    diaphragm type that was on it. They said it would add 5 hp.
    I removed the airbox and put on a K&N sock. And I had somebody
    weld up hanger for a shorty XXXXXXX muffler. (Darn, I'm
    drawing a total blank for that exhaust manufacturer that
    used to have those removable discs--more discs, louder,
    fewer discs, quieter.) Anyway, that all made for an even
    lighter bike. Of course, I got rid of the battery and all that.
    You could see through it. No turn signals, but I used my
    hand signals religiously--do I get points? Anyway, it all
    made for a blast of a bike from my vantage point. I also
    put some stiffer, longer shocks on it, so the modus
    operandi on every commuter corner was to hang out
    the back end. That was the beauty of the bike's low
    power and light weight. You could nail it in every gear
    as you slammed it on its side and the thing would do
    no wrong. Okay, in the rain one day, the back end
    went out too far....,but that was poor judgement. :)

    Great bike. I miss mine.
    #29
  10. eric123

    eric123 Gott Mit Uns

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    Damn, yer killing me here. I sold all my GN400 stuff this summer and have been regretting it ever since...
    #30
  11. argentcorvid

    argentcorvid Some Guy

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    Location:
    Marshmellow-town, Iowa
    Supertrapp.
    #31
  12. NJ-Brett

    NJ-Brett Brett

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    Location:
    Southern New Jersey
    These look like cool bikes.
    I wish Suzuki would dust off the gn400 motor and make a TU400.
    The old gn250 motor looks very close to the TU250 motor.

    It also looks like a great platform for my dream bike, a standard with a good seat, dual shock, street and mellow dirt bike that can do 2 up on the street with some comfort, enough suspension and low weight to do well on dirt roads and trails, robust and easy to service, and cool sounding.

    I had a number of old Triumph Daytona's and they fit the bill, but were flawed with a lot of vibration (broke things), a 4 speed trans, a weak clutch and transmission.
    If you could fit a modern air cooled motor in that frame, it would have been great.

    I will add this bike to the list of great bikes you can no longer get parts for, the sr500, the sl350, gn400, etc.
    #32
  13. royota

    royota n00b

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    Eric I sold one a couple years ago and regretted it. I kept a titled frame and recently bought a couple motors and parts from the guy you sold your bike and parts to. I'm missing the cdi and dont want to spend the coin on an ebay unit so I have been wanting to get info on a different route.
    #33
  14. eric123

    eric123 Gott Mit Uns

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    Unfortunately I don't have one. The guys at he Chinden shop may have one. They had a old DR400(same motor)awhile back that would have the same unit.

    Don't forget to post pics too...
    #34
  15. Andyvh1959

    Andyvh1959 Cheesehead Klompen

    Joined:
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    Location:
    Da frozen tundra eh? 1.5 mile west of Lambeau
    Newest update on the CDI replacement on my GN400 ice racer/flat-tracker:

    The combo CDI/COIL unit proved out to not produce enough spark energy to do anything more than just idle slowly, with the plug gapped at only 0.015". Generally speaking, a coil must produce about 1000 volts output per 0.001" of plug gap. So for the typical 0.025" spark plug gap the coil must output about 25,000 volts. Well, I proved the combo CDI/COIL unit I was testing could only produce maybe 15,000 volts. Enough to make it idle but it would not run on ANY addition throttle.

    So I went back to the stock Suzuki coil, fired by a Honda CH250 scooter CDI, using the P1 pulser (red/green wire from the timing plate) signal for 10 degree BTDC static/idle timing. Plug gapped at 0.025", bike fired easily on one kick stone cold. Idled out steadily nice, right away, on the Mikuni VM36 round slide carb I mounted. I played a bit with the carb tuning, have the needle on the middle clip position. I did find out I was using the P2 trigger signal to the CDI previously. Doing that advanced the static timing to 25 degrees BTDC. NO WONDER the damn thing was kicking back SO hard!! Now with the P1 trigger to the CDI it kicks easy and starts right off.

    I have heard from some tuners that using the CH250 (Elite scooter) CDI causes the bike to run hotter because of the internal advance curve in the digital CDI. Not sure I agree with that. The bike is using the P1 trigger signal for idle timing and the advance on the CH250 CDI doesn't start until about 2500 rpm. More to come one I get the bike on the ice to test it out. Sure looks cool for a lowly GN400 doesn't it?
    [​IMG]
    #35
  16. royota

    royota n00b

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    Thanks Andy for the PM and update is there a wiring diagram you can post, that would be a great help.
    #36
  17. Andyvh1959

    Andyvh1959 Cheesehead Klompen

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    Location:
    Da frozen tundra eh? 1.5 mile west of Lambeau
    If you go to yahoo.com/groups and look up the GN400 group you'll find all kinds of details on wiring, ignitions, service manuals, mods, etc. Myself and a core group of members have done quite a bit of work on these GN400s.

    Try this:
    http://autos.groups.yahoo.com/group/GN400/

    My next test will be of a CDI for a newer model GN250. I found one on ebay for $30. Worth a try.
    #37
  18. jjgres

    jjgres Been here awhile

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    Dec 14, 2008
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    156
    My pop rode a GN400 from Miami to San Diego and back.

    No problems.
    #38
  19. Turbo Ghost

    Turbo Ghost Been here awhile

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    Sep 27, 2008
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    260
    I had an 81 GN400 from 1990-91. It was the black and gold model with the Enkei mag wheels. Bought it for $500. I rode the heck out of that thing! Had a lot of fun on group rides firing Meguires! (hit kill switch at speed and pin throttle then switch back on for a massive boom!) I eventually traded it for a Virago but, I put several thousands of miles on it while I had it. Great little bike!
    #39
  20. Andyvh1959

    Andyvh1959 Cheesehead Klompen

    Joined:
    Feb 16, 2012
    Oddometer:
    814
    Location:
    Da frozen tundra eh? 1.5 mile west of Lambeau
    I'm working with a aftermarket producer of CDI units to develop a reliable, inexpensive, modern CDI to replace the heavy, ancient 33+ year old NipponsDenso CDI on the GN.

    I'll be testing four different CDI units, along with tracking the advance curve and max rpm capability, and butt-dyno evaluations.
    #40