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

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

  1. NJ-Brett

    NJ-Brett Brett

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    I wonder how the new sr400 will compare to the old gn400.
    #61
  2. Robb

    Robb Long timer

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    Been beating the bushes, haven't had any luck finding a titled frame for this GN400 ... still looking, but may end up parting it out. Cosmetically shabby, but a good runner. Anyone need a spare motor, carb, electricals, wheels, anything? Drop me a PM.
    #62
  3. wegface22

    wegface22 Adventurer

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    I have a gn250. Nobody says they like it, always ask why the hell i bought it. If they can ride i toss them the keys, they come back with a different opinion. :1drink
    Not fast, not modern, but honest, simple, cheap, comfy and more fun than expected. I think the 400 should be really good....
    "Olds cool"
    #63
  4. Andyvh1959

    Andyvh1959 Cheesehead Klompen

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    Why do you need a titled frame? If the VIN number (old style number on that vintage) is on the frame and engine. simply apply for a replacement title at the DMV. If the frame and engine numbers don't match then its some more work. Or, check out the GN400 Yahoo Group forum. There is a member there selling a titled frame.
    #64
  5. Robb

    Robb Long timer

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    Am already on the GN400 Yahoo group, but haven't seen the person selling the titled frame, even though I've asked around. Do you have a link or some contact info? I'd be very grateful!

    As for the replacement title, I doubt they'll give me one - I mean, I show up with a bike and no documentation, they'll just accept a bill of sale and hand me a title? It's been my experience it doesn't work that way here in Wisconsin. If I'm wrong, school me, please!

    Robb
    #65
  6. Veemax

    Veemax Cape Town rocks!

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    My GN400

    [​IMG]

    :rofl
    #66
  7. AidanHodge

    AidanHodge n00b

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    Here's a little documentary series i'm making on me restoring my GN400. Unfortunately, my bike has several problems that I'm trying to fix so i can ride it with easy. The first problem is that it will bump start, but it wont kickstart. I found a couple reasons why it won't start. First, of course i had bad brown gas after two years of sitting, so i'm in the process of cleaning the tank. I've clean the carburetor as well which had some blockages. Second, the air filter... the poor airfilter cage was just stuffed with filter pillows when it is suppose to have a sock go around the outside of the cage. I suspect this could be the main reason why it won't start because it's getting less air flow than the carburetor would like. lastly, Upon inspecting the wire harness I found 4 exposed wires; pink, white/blue, orange, and white, all of which go to my lights, but two of which come directly from my stator and thus can short my stator before it has a chance to do anything. Also, my green/white wire which is suppose to branch off from the white.blue wire is disconnected and just hanging around under the seat, so id hate to see what else is wrong with it. Nonetheless, I fear that I may also have a problem with the cdi as mentioned on this forum.

    Anyway here is my documentry i'm about 10 vids deep.
    http://youtu.be/yBsBQVoiECw
    #67
  8. MATTY

    MATTY BORDER RAIDER

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    I had a GN400 in the late 80s as a work hack it was a well abused example when i purchased it from a work colegue.
    Sadly it came to a misserable end when the cam distroyed the cylinder head it still ran but was at that time just not practical for me to repair, i broke the bike sold the engine to a lad down on the south coast for beach racing.
    Any one on the forum in the UK or Europe who need any parts for a GN400, i still have some around, notably a kick start gear leaver front disk brake assembly front wheel and rotor (spoked wheel). front pipe. front forks with tree. Rear wheel (spoked) and no doubt a few other bits and pieces but nothing that springs to mind here and now.
    Anybody needs anything give me a shout. Bits will be cheap, just never throw anything away thats me. :rofl
    #68
  9. Andyvh1959

    Andyvh1959 Cheesehead Klompen

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    I say it's worth a shot. Wis DMV can still run a trace on the VIN to check if there is any history that would block you from obtaining a replacement title. I have a 83 Honda XL600 that I bought back in 96, $200, bucket of parts for the engine, kid had no title, cash sale. I plan to submit the VIN at the DMV in Green Bay to see if I can get a replacement title for it. I want to build it into a retro-motard for bombing around town, 2-Wheel Tuesday events.
    #69
  10. jpman46

    jpman46 n00b

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    I have a 1982 GN400 that has gone through all the issues talked about here. Read and took notes on about five pages of your work andyvh1959. This s my first response on a forum but just lettiin' you know your audience has just grown by one more.
    #70
  11. warkshop

    warkshop uncbob

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    We used the GN250s in the Ohio MSF training, awesome bikes, tough as nails. The GZ replacement was a bad idea in my opinion,,,same motor i believe. I recall way back in days of old that the Suzi 400 enduro was a super vibration machine, no counter balancer,,,,never ridden a GN400. If it too has no balancer then beware 'o' vibes!
    #71
  12. Turbo Ghost

    Turbo Ghost Been here awhile

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    You're looking at it wrong! When I had mine, girls LOVED riding with me especially when I kept the motor screaming! I'm surprised my girlfriend didn't leave me for the GN!
    #72
  13. Andyvh1959

    Andyvh1959 Cheesehead Klompen

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    Da frozen tundra eh? 1.5 mile west of Lambeau
    Actually, for a big ol single it doesn't vibe as bad as you think. For around town it is a fun little ride.
    #73
  14. jpman46

    jpman46 n00b

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    So as I understand it right now the fix for replacing/upgrading my stock CDI is to use the Honda Elite CDI. Then do you suggest using the Honda coil as well? As the GN is a 6 volt system I am just wondering?
    Another thought I had was the feasibility and or practicality of being able to use the system that is on the current TU250s. Can they be modified to fit/work? They are 12 volt but I was curious If it is even possible or practical.
    #74
  15. DisorganizedVince

    DisorganizedVince Been here awhile

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    No mention of them yet, probably because 125cc 4 stroke road bikes don't light up many people's radars, but (4 years ago when England's licensing system made you do a test on a <125cc bike, and then be restricted to 33bhp for 2 years before being allowed anything bigger) I did my bike test on a GN125, and had a couple of test goes on it too. I got along well with my tutor and knew her before the tests too, so after I passed my test she asked me to ride it back to the school by myself for her before I went home and jumped on my KLR250 :D It'll stick in my memory forever simply for that.

    At the time you had to do a theory test, then a small course in a parking lot to show you could handle the bike within certain limits, (while pretending you're on a road, checking blind spots, etc.) and then an on road test. One part was having to zig zag around cones, do a 180 turn and come out of it and have maintained the speed to accelerate enough to a certain speed measured by electronic loops on the ground, and then perform an emergency stop. My tutor told me that although I did it perfectly I better be damned careful on the on road test because I came out of the turn and got through the loops at a higher speed than anybody she'd seen on the 125s, and the examiner might expect me to go as fast as I could on the road (alot of people had problems going round the corner fast enough to be able to get up to speed for the loops) :rofl

    From what I remember it was a likeable enough bike, it was fairly comfortable if too low for me, with spongy suspension, and adequate brakes. Despite the suspension it handled pretty well. Being a 125 it was never going to be the fastest of bikes, but it'd do 60, accelerate well enough for a 4 stroke 125, and I preferred it to the other common "learner" bikes I'd been on (Honda CG125, etc.) I thought it was a pretty nice looking bike too, even if the one I rode was a beaten up school bike :evil

    I'd definitely recommend it to anybody looking for a 125cc 4 stroke road bike, and if I saw one for the right price I'd definitely take a look at the GN250/400
    #75
  16. Andyvh1959

    Andyvh1959 Cheesehead Klompen

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    Well, the CH250 Elite CDI only works in that it does produce a spark, best to use the Honda coil to go with it. But the real issue is the the CH250 CDI does not achieve full ignition advance till 7,000 rpm. The GN400 needs full ignition advance by at least 3,000 rpm. It will and does run on the CH250 CDI, using the trigger coil at the 10 DBTC position. But because it does not fully advance as needed, the most the GN400 will run is about 5,000 rpm. Above that it just peters out, feeling almost like it is running low on gas.

    At one time I had the CH250 CDI on my GN400 wired to the trigger coil at the 35 BTDC position. Makes it very hard to start, literally, even with motocross boots on it hurt my foot and ankle trying to kick start against early ignition. But, when it did run, holy crap what a difference. So it proved the GN400 needs the advanced timing to run at higher rpm. But it needs the 10 BTDC idle timing for starting. I'd guess that even up to 15 BTDC would work.

    So the search continues for a suitable CDI. I am probably going to try a replacement CDI from my 96 Arctic Cat ZR580 (carb model). It has no battery, runs the CDI direct off the rotor, non-regulated voltage.

    The TU250 system would require a LOT of changes on the GN400 to work. Better to find a system similar to the GN400, from maybe a dirt bike or ATV from the mid-80's that has aftermarket inexpensive replacement CDIs available from many suppliers.
    #76
  17. DisorganizedVince

    DisorganizedVince Been here awhile

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    What about the new GN125s and GN250s? Any chance the CDI from either of them would be workable?
    #77
  18. jpman46

    jpman46 n00b

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    [
    Okay I believe I have it now. I will just keep following this thread, while simultaneously starting with what I understand so far. The GN400 when it is running is such a fun bike (I have over 20 k that I put on this bike) that a viable solution would really make my day.


    QUOTE=Andyvh1959;26519587]Well, the CH250 Elite CDI only works in that it does produce a spark, best to use the Honda coil to go with it. But the real issue is the the CH250 CDI does not achieve full ignition advance till 7,000 rpm. The GN400 needs full ignition advance by at least 3,000 rpm. It will and does run on the CH250 CDI, using the trigger coil at the 10 DBTC position. But because it does not fully advance as needed, the most the GN400 will run is about 5,000 rpm. Above that it just peters out, feeling almost like it is running low on gas.

    At one time I had the CH250 CDI on my GN400 wired to the trigger coil at the 35 BTDC position. Makes it very hard to start, literally, even with motocross bots on it hurt my foot and ankle trying to kick start against early ignition. But, when it did run, holy crap what a difference. So it proved the GN400 needs the advanced timing to run at higher rpm. But it needs the 10 BTDC idle timing for starting. I'd guess that even up to 15 BTDC would work.

    So the search continues for a suitable CDI. I am probably going to try a replacement CDI from my 96 Arctic Cat ZR580 (carb model). It has no battery, runs the CDI direct off the rotor, non-regulated voltage.

    The TU250 system would require a LOT of changes on the GN400 to work. Better to find a system similar to the GN400, from maybe a dirt bike or ATV from the mid-80's that has aftermarket inexpensive replacement CDIs available from many suppliers.[/QUOTE]
    #78
  19. Andyvh1959

    Andyvh1959 Cheesehead Klompen

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    Nope, won't work. The GN400 has a 5-pin 6-volt AC Regulated ignition with no battery and a simple CDI. The GN400 used a simple early version of CDI that few road bikes used, and fewer continued to use and develop. The stock GN400 CDI is a brick compared to the newer more reliable ones. The issue with the newer GNs, is they have 6-pin 12-volt DC regulated ignition with a battery and a engine control module.

    The CDI or ignition system itself, has much less to do with engine size, as it does with type of ignition (AC versus DC) and the ignition timing curve built into the CDI. Like I said earlier, the 5-pin CDI from a Honda CH250 works, but only to the point of ignition advance. It does not advance the ignition early enough to make it work on the GN400.

    That's why the search goes on for a AC fired CDI system with an advance curve similar to the GN400. Maybe something from a Honda XR100, XR250, XR350 or XR400R may work but I've not studied the wiring circuit of the XR yet.
    #79
  20. Johann

    Johann commuterus tankslapperus

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    Would it be possible to convert the GN400 to points? The SP370 used points and many parts are interchangeable between SP370/SP400/GN400.

    The only schematics I can find for GN400s all show batteries.

    http://www.cmsnl.com shows a CDI for 235 Euros but system includes battery.
    http://www.internationalmotoparts.com/ also shows OEM CDIs but with battery in schematics.



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    #80